3-Hydroxypyridone-5-amide compounds and their medical uses

Abstract

The present invention discloses a 3-hydroxypyridone-5-amide compound and its medical use. Experiments have shown that the 3-hydroxypyridone-5-amide derivative can effectively inhibit the replication of herpes simplex virus in Vero cell lines, and some compounds have inhibitory activity against herpes simplex virus comparable to that of acyclovir. At the same time, the 3-hydroxypyridone-5-amide compound has a high inhibitory effect on acyclovir-resistant strains (HSV-1tkLTRZ1), can overcome the resistance of herpes simplex virus to the first-line drug acyclovir, has anti-herpes simplex virus effect, and can be used to prepare active drugs against herpes simplex virus. The general structural formula is as follows (I): #imgabs0#

Description

Technical Field

[0001] The present invention belongs to the field of medicinal chemistry, and specifically relates to a 3-hydroxypyridone-5-amide compound and its medical use, and is an application of the 3-hydroxypyridone-5-amide compound in the preparation of an anti-herpes simplex virus drug. Background Art

[0002] Herpes simplex virus (HSV-1 / 2, ACV) belongs to the alpha-herpesvirus family of human herpes viruses (HHV), a type A DNA virus. HSV-1 causes primary and recurrent vesicular eruptions, primarily on the lips and genital mucosa, while HSV-2 primarily causes genital herpes.

[0003] Nucleoside analogs represented by acyclovir (ACV) are the first-line drugs for the clinical treatment of herpes simplex virus infection. However, this type of drug currently has the following problems: (1) Long-term and excessive use can cause herpes simplex virus to develop resistance to ACV; (2) Nucleoside anti-herpes simplex virus drugs ACV have serious side effects, including neurotoxicity and kidney damage. Structural modification and modification based on acyclovir cannot solve the side effects of the parent nucleus itself, and it is also difficult to avoid drug resistance. Therefore, the development of anti-herpes simplex virus drugs with new structural types is a current research focus. Summary of the Invention

[0004] The object of the present invention is to provide a 3-hydroxypyridone-5-amide compound, which is a small molecule compound for treating herpes simplex virus, and its general formula is shown as (I):

[0005]

[0006] Wherein R is selected from hydrogen, aromatic group, aliphatic hydrocarbon group and heteroatom hydrocarbon group, specifically:

[0007] (1) The aryl group is selected from phenyl, substituted phenyl, benzyl, substituted pyridyl or substituted thiazolyl, wherein the substituent is selected from fluorine, chlorine, methyl, hydroxyl or trifluoromethyl;

[0008] (2) The aliphatic hydrocarbon group is selected from a C3-C5 alkyl group, preferably n-propyl, n-butyl, cyclopropyl or cyclopentyl;

[0009] (3) The heteroatom hydrocarbon group is selected from alkoxy or linoalkyl, preferably methoxy or 2-morpholinoethyl.

[0010] The 3-hydroxypyridone-5-amide compound is selected from any one of the following compounds:

[0011] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-N 7 -(2-hydroxyphenyl)-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0012] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -butyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0013] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -propyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0014] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -cyclopropyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0015] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -cyclopentyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0016] N 7 ,2-dibenzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0017] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(3-phenylpropyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0018] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(1-phenylethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0019] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(3-(trifluoromethyl)phenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0020] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy)-N 7 -(3-methylpyridin-2-yl)-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0021] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(pyridin-2-ylmethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0022] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(2,4-difluorobenzyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0023] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(2-fluoro-3-chlorophenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0024] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(5-methylthiazol-2-yl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0025] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -methoxy-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0026] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7-(2-morpholinylethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide,

[0027] 2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide.

[0028] Another object of the present invention is to provide the use of the 3-hydroxypyridone-5-amide compound in the preparation of an anti-herpes simplex virus active drug.

[0029] The present invention has the following beneficial effects: The 3-hydroxypyridone-5-amide compounds inhibit the replication of herpes simplex virus in Vero cell lines, with some compounds exhibiting inhibitory activity against herpes simplex virus comparable to that of acyclovir. Furthermore, the 3-hydroxypyridone-5-amide compounds exhibit a high inhibitory effect against acyclovir-resistant strains (HSV-1tkLTRZ1), overcoming the resistance of herpes simplex virus to the first-line drug acyclovir. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 .Cytotoxicity of the compounds of the present invention. DETAILED DESCRIPTION

[0031] The present invention will be further described in detail below with reference to the accompanying drawings and examples, but the embodiments of the present invention are not limited thereto. Without departing from the above-mentioned technical ideas of the present invention, various substitutions and changes can be made according to common technical knowledge and customary means in the field, and all should be included in the scope of the present invention.

[0032] Example 1. 2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-N 7 -(2-Hydroxyphenyl)-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide (1)

[0033] Preparation of raw material 1a:

[0034] 1-(2,2-Dihydroxyethyl)-3-hydroxy-4-oxo-1,4-dihydropyridine-2,5-dicarboxylic acid (10 g, 21.67 mmol) was added to 50 ml of methanol, followed by 2,6-dimethylbenzene isocyanate (21.67 mmol, 2.84 g) and benzylamine (43.34 mmol, 4.73 ml). The reaction was allowed to proceed at room temperature for 2 to 3 days until completion, monitored by TLC. After completion, the reaction was filtered to obtain a white crude product. The crude product was slurried with methanol, filtered, and dried to obtain a pure white solid. The yield was 50%. White solid, mp:>250°C; 1H NMR (500 MHz, DMSO-d6) δ15.35 (s, 1H), 12.39 (s, 1H), 9.80 (s, 1H), 8.82 (s, 1H), 7.47–7.38 (m, 4H), 7.38–7.33 (m, 1H), 7.08–6.99 (m, 3H), 5.17 (d, J=15.2 Hz, 1H), 5.00 (d, J=13.0 Hz, 1H), 4.81 (d, J=13.9 Hz, 2H), 4.37 (d, J=15.2 Hz, 1H), 1.95 (s, 6H). 13 C NMR(125MHz,DMSO-d6)δ172.2,165.3,164.9,163.5,152.5,140.7,134.9,134.6,133.6, 128.7,128.3,127.9,127.8,126.9,112.8,56.2,53.1,49.5,39.2,17.8.HRMS(ESI):m / z calcdfor(C 25 H 23 N3O6+H) + :462.1620; found:462.1625.

[0035] Raw material 1a (0.433 mmol, 200 mg) was dissolved in DMF, and DIPEA (0.866 mmol, 151 μL) was added. The mixture was then placed in a cold trap and cooled to 0°C. HATU (0.530 mmol, 200 mg) was added while still cooling, and the mixture was stirred at 0°C for 10-20 min. o-Hydroxyaniline (0.866 mmol, 72 μL) was then added, and stirring continued at 0°C for 10-20 min. The system was then allowed to warm to room temperature and allowed to react overnight until the reaction was complete. TLC monitoring of the reaction was performed, and the system was poured into water (5-10 times the amount of DMF). A large amount of solid immediately precipitated, and the crude product was filtered. The crude product was purified by column chromatography to obtain a white solid in a 56% yield. This white solid had an mp > 250°C. 1H NMR(500MHz,DMSO-d6)δ12.31(s,1H),12.10(s,1H),10.00(s,1H),9.78(s,1H),8.68( s,1H),8.38(d,J=7.9Hz,1H),7.47–7.39(m,4H),7.37–7.33(m,1H),7.03(q,J=5.6Hz,3 H),6.91(d,J=4.0Hz,2H),6.79(dp,J=8.5,4.1Hz,1H),5.23(d,J=15.2Hz,1H),4.95(dd ,J=15.1,2.9Hz,1H),4.76(dd,J=7.0,3.5Hz,2H),4.31(d,J=15.2Hz,1H),1.97(s,6H). 13 C NMR(125MHz,DMSO-d6)δ170.1,165.2,161.6,153.4,146.6,140.3,135.3,134.7,133.8,128.7,128.2, 127.8,127.8,127.1,126.8,123.6,120.3,118.9,117.9,114.6,56.5,52.9,49.4,17.8.HRMS(ESI):m / z calcd for(C 31 H 28 N4O6+H) + :553.2042,found:553.2048.

[0036] Example 2. 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -Butyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0037] Except that o-hydroxyaniline was replaced by n-butylamine, the other steps were the same as in Example 1, and the yield was 48%.

[0038] White solid, mp>250℃. 1H NMR(500MHz,DMSO-d6)δ12.07(s,1H),9.97(t,J=5.7Hz,1H),9.75(s,1H),8.54(s,1H),7.47 –7.37(m,4H),7.37–7.32(m,1H),7.03(q,J=5.7Hz,3H),5.21(d,J=15.3Hz,1H),4.94–4.86( m,1H),4.71(d,J=10.4Hz,2H),4.28(d,J=15.3Hz,1H),3.30(dt,J=12.7,7.1Hz,2H),1.96(s ,6H),1.48(dq,J=8.5,6.9Hz,2H),1.38–1.30(m,2H),0.90(t,J=7.4Hz,3H).HRMS(ESI):m / z calcd for(C 25 H 23 N3O6+H) + :517.2406,found:517.2415.

[0039] Example 3. 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -propyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0040] Propylamine was used instead of o-hydroxyaniline. Other procedures were the same as in Example 1. The yield was 48%.

[0041] White solid, mp>250℃. 1 H NMR(500MHz,DMSO-d6)δ12.05(s,1H),9.98(t,J=5.6Hz,1H),9.92(s,1H),8.5 2(s,1H),7.47–7.31(m,5H),7.03(q,J=5.7Hz,3H),5.19(d,J=15.3Hz,1H),4. 79(s,1H),4.75–4.70(m,1H),4.28(d,J=15.1Hz,1H),2.28(t,J=7.3Hz,1H),1 .96(s,6H),1.51(h,J=7.2Hz,2H),1.42(s,2H),0.88(dt,J=24.7,7.2Hz,3H). 13CNMR(125MHz,DMSO-d6)δ165.1,163.9,163.3,153.4,139.9,135.2,134.7,133.8,128.7,128. 2,127.8,127.7,126.8,115.5,56.4,52.6,49.3,37.9,31.2,19.6,17.8,13.6.HRMS(ESI):m / z calcd for(C 28 H 30 N4O5+H) + :503.2250,found:503.2258.

[0042] Example 4.2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -cyclopropyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0043] Cyclopropylamine was used instead of o-hydroxyaniline. Other steps were the same as in Example 1. The yield was 50%.

[0044] White solid, mp>250℃. 1 H NMR(500MHz,DMSO-d6)δ12.08(s,1H),9.99(d,J=4.6Hz,1H),9.75(s,1H),8.55(s ,1H),7.47–7.37(m,4H),7.37–7.32(m,1H),7.04(q,J=5.6Hz,3H),5.21(d,J=15.3 Hz,1H),4.95–4.87(m,1H),4.71(d,J=10.4Hz,2H),4.28(d,J=15.3Hz,1H),2.86(t t,J=8.5,3.7Hz,1H),1.96(s,6H),0.77–0.70(m,2H),0.50(tt,J=5.2,3.0Hz,2H). 13 C NMR (125MHz, DMSO-d6) δ170.2,165.1,164.5,163.9,153.4,139.7,135.2,134.7,133.8,128.7,128 .2,127.8,127.7,126.8,117.8,115.3,56.4,52.6,49.3,39.2,22.1,17.8,6.3,6.3.HRMS(ESI):m / z calcd for(C 28 H 30 N4O5+H) +:501.2093,found:503.2103.

[0045] Example 5. 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -cyclopentyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0046] Cyclopentylamine was used instead of o-hydroxyaniline. Other steps were the same as in Example 1. The yield was 37%.

[0047] White solid, mp>250℃. 1 H NMR(500MHz,DMSO-d6)δ12.06(s,1H),10.05(s,1H),9.75(s,1H),8.53(s,1H),7.42(d,J=11.7Hz,4H),7.35(s,1H),7.03(s,3H),5 .21(d,J=15.0Hz,1H),4.89(d,J=15.3Hz,1H),4.72(s,2H),4.31–4.14(m,2H),1.96(s,6H),1.90(s,3H),1.67(d,3H),1.44(s,2H). 13 C NMR (125MHz, DMSO-d6) δ170.2,163.9,162.7,139.84,135.2,134.7,133.8,128.7,128.2,1 27.8,126.8,117.7,115.5,56.4,52.6,50.0,49.3,32.8,32.7,23.2,17.8.HRMS(ESI):m / z calcd for(C 30 H 32 N4O5+H) + :529.2406,found:529.2409.

[0048] Example 6.N 7 ,2-dibenzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0049] Benzylamine was used instead of o-hydroxyaniline. The rest of the process was the same as in Example 1. The yield was 40%.

[0050] White solid, mp>250℃. 1H NMR (500MHz, DMSO-d6) δ12.10(s,1H),10.36(t,J=6.0Hz,1H),9.76(s,1H),8.60(s,1H),7.42(dt,J=14.8,7.6Hz,4H),7.33(dt,J=13.7,7.5Hz, 5H),7.26(t,J=7.0Hz,1H),7.04(q,J=5.7Hz,4H),5.21(d,J=15.3Hz,1H ),4.92(d,J=12.7Hz,1H),4.74(s,2H),4.61–4.48(m,2H),1.97(s,6H). 13 C NMR(125MHz,DMSO-d6)δ165.1,163.9,163.5,153.5,140.1,139.2,135.2,134.7,133.8,128.7, 128.4,128.2,127.8,127.8,127.1,126.8,115.3,56.4,52.7,49.4,42.0,17.8.HRMS(ESI):m / z calcdfor(C 32 H 30 N4O5+H) + :551.2250,found:551.2252.

[0051] Example 7. 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(3-phenylpropyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0052] 3-phenylpropylamine was used instead of o-hydroxyaniline. The other steps were the same as in Example 1. The yield was 41%.

[0053] White solid, mp>250℃. 1H NMR(500MHz,DMSO-d6)δ12.09(s,1H),10.06(t,J=5.7Hz,1H),9.75(s,1H),8.55(s,1H),7.47–7. 38(m,4H),7.37–7.33(m,1H),7.29(t,J=7.5Hz,2H),7.24–7.21(m,2H),7.21–7.16(m,1H),7.07– 7.00(m,3H),5.21(d,J=15.3Hz,1H),4.94–4.86(m,1H),4.72(d,J=10.5Hz,2H),4.28(d,J=15.4H z,1H),3.29(ddd,J=13.1,8.2,5.2Hz,2H),2.64(t,J=7.6Hz,2H),1.96(s,6H),1.86–1.77(m,2H). 13 C NMR (125MHz, DMSO-d6) δ170.3,165.1,164.0,163.4,153.5,141.4,139.9,135.2,134.7,133.8,128.7,128. 3,128.2,128.2,127.8,127.7,126.8,125.7,56.4,52.7,49.3,39.2,37.7,32.4,30.9,17.8.HRMS(ESI):m / z calcd for(C 34 H 34 N4O5+H) + :579.2563,found:579.2571.

[0054] Example 8.2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(1-phenylethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0055] 1-phenylethylamine was used instead of o-hydroxyaniline. Other procedures were the same as in Example 1. The yield was 59%.

[0056] White solid, mp>250℃. 1H NMR(500MHz,DMSO-d6)δ12.08(s,1H),10.48(d,J=7.9Hz,1H),9.75(d,J=3.8Hz,1H), 8.54(d,J=5.3Hz,1H),7.47–7.31(m,9H),7.26(tt,J=4.9,3.3Hz,1H),7.09–6.97(m, 3H),5.22(d,J=15.3Hz,1H),5.14(t,J=7.4Hz,1H),4.90(dd,J=15.0,3.1Hz,1H),4.7 2(t,J=5.3Hz,2H),4.28(dd,J=15.3,8.1Hz,1H),1.93(s,6H),1.46(d,J=6.9Hz,3H). 13 C NMR (125MHz, DMSO-d6) δ170.3,165.1,163.8,162.6,153.4,144.0,139.9,135.2,134.7,133.7,128.7,128.4,12 8.2,127.8,127.7,126.8,126.8,125.7,117.8,115.4,56.4,52.7,49.3,47.9,39.2,23.0,17.8.HRMS(ESI):m / z calcd for(C 33 H 32 N4O5+H) + :565.2406,found:565.2401.

[0057] Example 9.2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(3-(Trifluoromethyl)phenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0058] m-Trifluoromethylaniline was used instead of o-hydroxyaniline. The rest of the process was the same as in Example 1. The yield was 62%.

[0059] White solid, mp>250℃. 1H NMR(500MHz,DMSO-d6)δ12.67(s,1H),12.25(s,1H),9.77(s,1H),8.73(s,1H),8 .28(d,J=2.0Hz,1H),7.79(dd,J=8.0,2.0Hz,1H),7.60(t,J=8.0Hz,1H),7.48–7. 39(m,5H),7.38–7.33(m,1H),7.03(q,J=5.8Hz,3H),5.21(d,J=15.2Hz,1H),4.9 7(d,J=13.0Hz,1H),4.79(d,J=14.0Hz,2H),4.33(d,J=15.3Hz,1H),1.97(s,6H). 13 CNMR(125MHz,DMSO-d6)δ170.5,165.1,163.9,162.4,153.5,140.4,139.1,135.1,134.7,133.8,130.2,129.7(d,J=31.3Hz),128.7,128.3 ,127.9,127.8,126.9,125.1,123.4,123.0,120.1(d,J=4.0Hz),118.3,115.8(d,J=4.1Hz),114.9,56.4,53.0,49.4,17.8.HRMS(ESI):m / z calcd for(C 32 H 27 F3N4O5+H) + :565.2406,found:565.2404.

[0060] Example 10.2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy)-N 7 -(3-methylpyridin-2-yl)-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0061] 3-Methyl-2-aminopyridine was used instead of o-hydroxyaniline. Other procedures were the same as in Example 1. The yield was 55%.

[0062] White solid, mp>250℃. 1H NMR (500MHz, DMSO-d6) δ12.19(s,1H),9.77(s,1H),8.70(s,1H),8.28(dd,J=4.8,2.1 Hz,1H),7.71(dd,J=7.6,2.0Hz,1H),7.43(dt,J=15.0,7.2Hz,4H),7.38–7.33(m,1H) ,7.21(dd,J=7.5,4.7Hz,1H),7.07–7.00(m,4H),5.21(d,J=15.3Hz,1H),5.02–4.94( m,1H),4.77(dq,J=8.4,4.3Hz,2H),4.32(d,J=15.1Hz,1H),2.25(s,3H),1.97(s,6H). 13 C NMR (125MHz, DMSO-d6) δ170.5,165.1,163.9,161.3,153.5,149.6,145.8,140.4,139.2,135.2,134.7,128 .7,128.2,127.8,127.8,127.4,126.9,121.3,118.2,115.1,56.4,52.9,49.4,17.8,17.7.HRMS(ESI):m / z calcd for(C 31 H 29 N5O5+H) + :552.2202,found:552.2207.

[0063] Example 11.2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(pyridin-2-ylmethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0064] 2-Aminomethylpyridine was used instead of o-hydroxyaniline. Other steps were the same as in Example 1. The yield was 45%.

[0065] White solid, mp>250℃. 1H NMR(500MHz,DMSO-d6)δ12.10(s,1H),10.38(t,J=6.0Hz,1H),9.74(s,1H),8.60 –8.53(m,2H),8.47(dd,J=4.9,1.8Hz,1H),7.71(dt,J=7.8,2.1Hz,1H),7.47–7.3 1(m,6H),7.06–7.01(m,3H),5.21(d,J=15.3Hz,1H),4.94–4.86(m,1H),4.72(d,J =11.0Hz,2H),4.57(qd,J=15.0,6.0Hz,2H),4.28(d,J=15.3Hz,1H),1.96(s,6H). 13 CNMR(125MHz,DMSO-d6)δ170.2,165.1,164.0,163.7,153.5,148.8,148.1,140.1,135.2,135.0,134.9,134 .7,133.8,128.7,128.2,127.8,127.8,126.8,123.5,117.8,115.2,56.4,52.7,49.4,17.8.HRMS(ESI):m / z calcd for(C 31 H 29 N5O5+H) + :552.2202,found:552.2201.

[0066] Example 12. 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(2,4-difluorobenzyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0067] 2,4-difluoroaniline was used instead of o-hydroxyaniline. Other steps were the same as in Example 1. The yield was 43%.

[0068] White solid, mp>250℃. 1H NMR(500MHz,DMSO-d6)δ12.10(s,1H),9.74(s,1H),8.57(s,1H),7.47–7.38(m,5H),7.37–7.33(m,1H),7.24(ddd,J=10.5,9.3,2.6Hz,1H),7 .09–7.00(m,4H),5.21(d,J=15.2Hz,1H),4.95–4.86(m,1H),4.72(d,J=11.1Hz,2H),4.61–4.49(m,2H),4.28(d,J=15.3Hz,1H),1.96(s,6H). 13 C NMR(125MHz,DMSO-d6)δ170.3,165.2,164.0,163.6,153.5,140.1,135.2, 134.7,133.8,128.7,128.2,127.9,127.8,126.9,122.4(d,J=3.5Hz),122. 3(d,J=3.6Hz),117.9,115.2,111.4(d,J=3.5Hz),111.3(d,J=3.5Hz),103. 8(t,J=25.6Hz),56.4,52.7,49.4,35.7(d,J=3.5Hz),17.8.HRMS(ESI):m / z calcd for(C 31 H 26 F2N4O5+H) + :573.1905,found:573.1911.

[0069] Example 13.2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(2-Fluoro-3-chlorophenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0070] 3-chloro-2-fluoroaniline was used instead of o-hydroxyaniline. The rest of the process was the same as in Example 1. The yield was 46%.

[0071] White solid, mp>250℃. 1H NMR(500MHz,DMSO-d6)δ10.34(s,1H),10.02(s,1H),8.47(s,1H),7.37(t,J=7.4Hz,9H),7.05–6.97(m,3H),5 .12(d,J=15.1Hz,1H),5.03–4.93(m,2H),4.72(dd,J=14.3,4.4Hz,1H),4.31(d,J=15.1Hz,1H),1.95(s,6H). 13 C NMR (125MHz, DMSO-d6) δ170.2,165.3,164.1,163.5,153.5,139.9,135.4,134.8,134.1,128.7,128.3 ,127.7(d,J=12.5Hz),126.8,117.4,115.4,70.7,58.1,56.6,53.1,49.6,38.3,18.0.HRMS(ESI):m / z calcd for(C 31 H 26 FClN4O5+H) + :589.1609,found:589.1616.

[0072] Example 14. 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(5-methylthiazol-2-yl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0073] 2-amino-5-methylthiazole was used instead of o-hydroxyaniline. The rest of the process was the same as in Example 1. The yield was 40%.

[0074] White solid, mp>250℃. 1 H NMR(500MHz,DMSO-d6)δ13.50(s,1H),12.33(s,1H),9.79(s,1H),8.80(s,1H),7.47–7.39(m,4H),7.38–7.33(m,1H),7.03(q,J=5.8Hz,3H), 6.83(s,1H),5.20(d,J=15.2Hz,1H),4.98(d,J=12.6Hz,1H),4.79(d,J=12.9Hz,2H),4.34(d,J=15.2Hz,1H),2.32–2.25(m,3H),1.97(s,6H). 13C NMR (125MHz, DMSO-d6) δ170.4,165.0,163.8,161.3,153.5,147.1,140.4,135.1,134.7,133.7,128.7 ,128.2,127.8,127.8,126.9,118.4,113.2,108.5,56.3,53.0,49.4,39.0,17.8,16.9.HRMS(ESI):m / z calcd for(C 29 H 27 N5O5S+H) + :558.1766,found:558.1760.

[0075] Example 15.2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -methoxy-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0076] Methoxyamine hydrochloride was used instead of o-hydroxyaniline. Other steps were the same as in Example 1. The yield was 66%.

[0077] White solid, mp>250℃. 1 H NMR (500MHz, DMSO-d6) δ12.16(d,J=8.7Hz,2H),9.75(s,1H),8.58(s,1H),7.43–7.40(m,3H),7.37–7.32(m,1H),7.08–7.00( m,4H),5.20(d,J=15.2Hz,1H),4.95–4.89(m,1H),4.73(d,J=10.4Hz,2H),4.29(d,J=15.2Hz,1H),3.72(s,3H),1.96(s,6H). 13 C NMR (125MHz, DMSO-d6) δ169.4,165.1,163.9,161.6,153.3,139.8,135.1,134.7,133.7,128.7,128.3 ,128.2,127.8,127.8,126.8,117.9,114.7,63.7,56.4,52.7,49.4,39.2,17.8,17.8.HRMS(ESI):m / z calcd for(C 26 H 26 N4O6+H) + :491.1886,found:491.1889.

[0078] Example 16.2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(2-morpholinoethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0079] N-(2-aminoethyl)morpholine was used instead of o-hydroxyaniline. The rest of the process was the same as in Example 1. The yield was 43%.

[0080] White solid, mp>250℃. 1 H NMR(500MHz,DMSO-d6)δ12.07(s,1H),10.03(t,J=5.5Hz,1H),9.75(s,1H),8.53(s,1H), 7.47–7.38(m,4H),7.35(t,J=7.0Hz,1H),7.08–7.00(m,3H),5.21(d,J=15.2Hz,1H),4.92 –4.85(m,1H),4.71(d,J=12.4Hz,2H),4.28(d,J=15.3Hz,1H),3.59(t,J=4.6Hz,4H),3.43 (q,J=6.1Hz,2H),3.33(s,1H),2.45(t,J=6.3Hz,2H),2.41(d,J=4.8Hz,3H),1.96(s,6H). 13 C NMR(125MHz,DMSO-d6)δ170.1,165.1,164.0,163.3,153.5,139.9,135.2,134.7,133.8,128.7,1 28.2,127.8,127.7,126.8,117.7,66.2,57.2,56.4,53.1,52.6,49.3,35.5,17.8.HRMS(ESI):m / z calcd for(C 31 H 35 N5O6+H) + :574.2621,found:574.2626.

[0081] Example 17. 2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide

[0082] 2-Benzyl-3-((2,6-dimethylphenyl)aminocarbonyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-7-carboxylic acid (27) (0.433 mmol, 200 mg) was added to a reaction flask, and 5 mL of methanol was added to obtain a suspension. The suspension was then placed in a cold trap and cooled to 0°C. Thionyl chloride (0.866 mmol, 63 μL) was slowly added dropwise. After the addition was complete, the suspension turned clear. After reacting in the cold trap for 1-2 hours, the temperature was naturally raised to room temperature and the reaction was continued overnight. After TLC detection, the system was directly dried to obtain the intermediate methyl esterification product. The intermediate was not further purified and was directly used in the next reaction. The methyl esterification intermediate was added to a sealed tube, and methanol and 30% ammonia water (20 mL) in a volume ratio of 1:1 were added. The reaction was heated in a sealed tube at 50-60°C overnight until the reaction was complete. After TLC monitoring, the reaction was completed and the system was directly dried to obtain the crude product. The crude product was purified by column chromatography to obtain a white solid in a 30% yield. The white solid had an mp of >250°C. 1 H NMR(500MHz,DMSO-d6)δ12.06(s,1H),9.74(s,1H),9.25(d,J=4.7Hz,1H),8.55(s,1H),7.52(d,J=4.7Hz,1H),7.45–7.38(m,4H),7.37– 7.33(m,1H),7.08–7.00(m,3H),5.21(d,J=15.2Hz,1H),4.91–4.83(m,1H),4.71(d,J=11.3Hz,2H),4.28(d,J=15.3Hz,1H),1.96(s,6H). 13 C NMR(125MHz,DMSO-d6)δ170.3,165.2,164.8,164.0,153.6,140.3,135.2,134.7,133.8, 128.7,128.2,127.8,127.8,126.8,117.7,115.8,56.5,52.7,49.4,17.8.HRMS(ESI):m / z calcd for(C 25 H 24 N4O5+H) + :461.1780,found:461.1789.

[0083] Example 18. Antiviral effect of the compounds disclosed in the present invention in HSV-1 infected Vero cells

[0084] Prepare 100 μL of cell suspension in a 96-well plate and seed 3 × 10 4Vero cells were pre-incubated in an incubator for 24 hours (37°C, 5% CO2). Test substances were added to the plates at 20 μM and 2 μM concentrations, with three replicates for each drug. A DMSO negative control group and an ACV positive control group were also established. Vero cells were infected with HSV-1 virus at an MOI of 0.01. Luciferase activity in infected cells was measured using a Firefly Luciferase Assay Kit (Yeasen Biotech 11401ES) 36 hours after infection (37°C, 5% CO2). Luminescence intensity was measured using a Thermo Scientific full-wavelength scanning multi-function reader. Data were analyzed using GraphPad Prism 9.0.0 software. Relative inhibition (%) = fluorescence intensity of drug-treated group / fluorescence intensity of negative control group × 100.

[0085] The inhibition rate results of Examples and acyclovir (ACV) are shown in Table 1. The results show that the 3-hydroxypyridone-5-amide compounds can effectively inhibit herpes simplex virus in Vero cells, and Example 17 has comparable inhibitory activity to acyclovir.

[0086] Table 1. In vitro activity against herpes simplex virus replication

[0087]

[0088]

[0089] Example 19. Inhibitory activity against acyclovir-sensitive strain (HSV-1KOS)

[0090] Drug treatment and viral infection:

[0091] 1.5×10 5 Vero cells were inoculated into 24-well plates. 500 μL of cell suspension was prepared in a 24-well plate. The culture plate was pre-cultured in an incubator for 24 hours (conditions were 37°C, 5% CO2). The drug to be tested was diluted gradiently, at least 5 concentration gradients to be tested were set, and 3 parallel replicates were set for each drug concentration. Different concentrations of the test substance were added to the culture plate, and HSV-1KOS virus was used to infect Vero cells at MOI = 0.01. After 24 hours of infection (conditions were 37°C, 5% CO2), the cells were scraped, the cells and supernatant were collected, and repeated freezing and thawing was performed three times. 1.5×10 5 Vero cells were seeded into 24-well plates. 500 μL of cell suspension was prepared in the 24-well plates. The plates were pre-incubated in an incubator for 24 hours (37°C, 5% CO2). 5 μL and 20 μL of the test substance were added to the plates. Vero cells were infected with HSV-1 virus at an MOI of 0.01.

[0092] Determination of sample virus titer:

[0093] Vero cells were plated one day in advance. A 24-well plate was used with a cell density of 1x10 5 Cells / well. Perform a 10-fold serial dilution of the frozen-thawed sample. After aspirating the culture medium from the plate, add 200 μL of the dilution to each well and incubate at 37°C, 5% CO₂ for 1 hour (shaking every 15 minutes) to allow for viral adsorption. After 1 hour of incubation, add 0.5 mL of methylcellulose culture medium to each well and incubate at 37°C for 2-3 days. After 2-3 days, plaques should be observed under a microscope. Add a 1:1 (v / v) formaldehyde-acetic acid fixative to the plate and let it sit for at least 0.5 hour. Rinse the fixed cell monolayer with water, then stain with crystal violet stain, let it sit for at least 0.5 hour, rinse with water, and air dry. Count the fixed and stained plaques using a stereomicroscope to calculate the viral titer (PFU / mL, plaque formation unit): PFU / mL = number of viral plaques / 5 × dilution factor. The number of plaques at different concentrations was used to generate a dose-dependent curve using GraphPad Prism 9.0.0, and the EC was determined by fitting the dose-dependent curve using Prism. 50 .

[0094] Example 17 and EC of acyclovir 50 The results are shown in Table 2. The results show that Example 17 is comparable to acyclovir.

[0095] Table 2. EC of Example 17 and acyclovir against HSV-1 KOS strain 50 value

[0096] Compound <![CDATA[EC 50 / μM]]> Compound <![CDATA[EC 50 / μM]]> 17 5.667 ACV 0.086

[0097] Example 20. Inhibitory activity against acyclovir-resistant strain (HSV-1tkLTRZ1)

[0098] Drug treatment and viral infection:

[0099] 1.5×10 5Vero cells were inoculated into 24-well plates. 500 μL of cell suspension was prepared in a 24-well plate. The culture plate was pre-cultured in an incubator for 24 hours (conditions were 37°C, 5% CO2). The drug to be tested was diluted gradiently, at least 5 concentration gradients to be tested were set, and 3 parallel replicates were set for each drug concentration. Different concentrations of the test substance were added to the culture plate, and the HSV-1tkLTRZ1 acyclovir-resistant strain was used to infect Vero cells at MOI = 0.01. After 24 hours of infection (conditions were 37°C, 5% CO2), the cells were scraped, the cells and supernatant were collected, and repeated freezing and thawing was performed three times. 1.5×10 5 Vero cells were seeded into 24-well plates. 500 μL of cell suspension was prepared in the 24-well plates. The plates were pre-incubated in an incubator for 24 hours (37°C, 5% CO2). 5 μL and 20 μL of the test substance were added to the plates. Vero cells were infected with the acyclovir-resistant HSV-1tkLTRZ1 strain at an MOI of 0.01.

[0100] Determination of sample virus titer:

[0101] Vero cells were plated one day in advance. A 24-well plate was used with a cell density of 1x10 5 Cells / well. Perform a 10-fold serial dilution of the frozen-thawed sample. After aspirating the culture medium from the plate, add 200 μL of the dilution to each well and incubate at 37°C, 5% CO₂ for 1 hour (shaking every 15 minutes) to allow for viral adsorption. After 1 hour of incubation, add 0.5 mL of methylcellulose culture medium to each well and incubate at 37°C for 2-3 days. After 2-3 days, plaques should be observed under a microscope. Add a 1:1 (v / v) formaldehyde-acetic acid fixative to the plate and let it sit for at least 0.5 hour. Rinse the fixed cell monolayer with water, then stain with crystal violet stain, let it sit for at least 0.5 hour, rinse with water, and air dry. Count the fixed and stained plaques using a stereomicroscope to calculate the viral titer (PFU / mL, plaque formation unit): PFU / mL = number of viral plaques / 5 × dilution factor. The number of plaques at different concentrations was used to generate a dose-dependent curve using GraphPad Prism 9.0.0, and the EC was determined by fitting the dose-dependent curve using Prism. 50 .

[0102] Example 17 and EC of acyclovir 50 The results are shown in Table 3. The results show that the inhibitory activity of acyclovir against acyclovir-resistant strain (HSV-1tkLTRZ1) decreased significantly, and Example 17 still retained the same EC level as the sensitive strain against the resistant strain. 50The results showed that 3-hydroxypyridone-5-amide compounds can solve the problem of drug resistance to the first-line drug acyclovir.

[0103] Table 3. EC of Example 17 and acyclovir against HSV-1 tkLTRZ1 strain 50 value

[0104] Compound <![CDATA[EC 50 ]]> Compound <![CDATA[EC 50 ]]> 17 8.279μM ACV 17.28μM

[0105] Example 21. Cytotoxicity of the compound of Example 17

[0106] 3×10 4 Vero cells were seeded into 96-well plates. 100 μL of cell suspension was prepared in the 96-well plate. The plate was pre-incubated in an incubator for 24 hours (at 37°C, 5% CO2). The test drug was diluted to 20 μM and 2 μM in the plate. Each well was incubated in the incubator for an appropriate period of time in DMEM medium containing 10% fetal bovine serum and 1% (v / v) penicillin-streptomycin solution. Subsequently, 10 μL of CCK-8 (Solarbio CA1210) solution was added to each well and incubated in the dark at 37°C for an additional hour. Cell viability was determined by measuring absorbance at 450 nm using a Thermo Scientific full-wavelength scanning multi-function reader.

[0107] Cell viability (%) = [A(drug added) - A(blank)] / [A(0 drug added) - A(blank)] × 100

[0108] A(drug added): absorbance of the wells with cells, CCK-8 solution and drug solution,

[0109] A (blank): absorbance of the well with culture medium and CCK-8 solution but no cells,

[0110] A (0 drug addition): absorbance of a well containing cells and CCK-8 solution but no drug solution.

[0111] Data analysis was performed by GraphPad Prism 9.0.0 software, and the cytotoxicity results are presented in Figure 1 middle.

[0112] The results showed that the compound of Example 17 had no obvious toxicity at 20 μM and 2 μM.

Claims

1. A 3-hydroxypyridone-5-amide compound, characterized in that: Its general formula is shown in (I): Wherein R is selected from hydrogen, aromatic group, aliphatic hydrocarbon group and heteroatom hydrocarbon group, specifically: (1) The aryl group is selected from phenyl, substituted phenyl, benzyl, substituted pyridyl or substituted thiazolyl, wherein the substituent is selected from fluorine, chlorine, methyl, hydroxyl or trifluoromethyl; (2) The aliphatic hydrocarbon group is selected from n-propyl, n-butyl, cyclopropyl or cyclopentyl; (3) The heteroatom hydrocarbon group is selected from methoxy and 2-morpholinylethyl.

2. The 3-hydroxypyridone-5-amide compound according to claim 1, characterized in that Any one of the following compounds: 2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-N 7 -(2-hydroxyphenyl)-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -butyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -propyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -cyclopropyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -cyclopentyl-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, N 7 ,2-dibenzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(3-phenylpropyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(1-phenylethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(3-(trifluoromethyl)phenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy)-N 7 -(3-methylpyridin-2-yl)-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(pyridin-2-ylmethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1, 2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(2,4-difluorobenzyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1, 2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(2-fluoro-3-chlorophenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(5-methylthiazol-2-yl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -methoxy-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-N 7 -(2-morpholinylethyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide, 2-Benzyl-N 3 -(2,6-dimethylphenyl)-9-hydroxy-1,8-dioxo-1,3,4,8-tetrahydro-2H-pyrido[1,2-a]pyrazine-3,7-dicarboxamide.

3. Use of the 3-hydroxypyridone-5-amide compound according to any one of claims 1 to 2 in the preparation of a drug with anti-herpes simplex virus activity.

Images