A regioselective metal catalyzed synthesis of annelated benzimidazoles and azabenzimidazoles
A compound, selected technology, applied in the direction of organic chemistry, etc., can solve the problems of poor cost-effectiveness, hindering the optimization of potential drug substances, and not showing universal applicability, so as to achieve the effect of easy acquisition, time-effectiveness and cost-effectiveness
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[0174] During the preparation of compounds of formula I, it is often advantageous or necessary to introduce functional groups which reduce or prevent undesired or side reactions in the various synthetic steps in the form of precursor groups which are subsequently converted into the desired functional groups, or by means of suitable Protecting group strategies for synthetic problems to temporarily block functional groups. Such strategies are well known to those skilled in the art (see eg Greene and Wuts, Protective Groups in Organic Synthesis, Wiley, 1991 or P. Kocienski, Protecting Groups, Thieme 1994). As an example of a precursor group there may be mentioned a cyano group which is converted into a carboxylic acid derivative in a subsequent step or into an aminomethyl group by reduction. A protecting group can also have the meaning of a solid phase, and cleavage from a solid phase means removal of the protecting group. The use of such techniques is known to those skilled in ...
Embodiment 1
[0199] Example 1: 2,3-Dihydro-1H-benzo[d]pyrrolo[1,2-a]imidazole
[0200]
[0201] (Method A): 1-iodo-2-nitrobenzene (125 mg, 0.5 mmol), pyrrolidin-2-one (51 mg, 0.6 mmol), palladium trifluoroacetate (13 mg, 0.04 mmol), BINAP (24 mg, 0.08 mmol) and cesium carbonate (212 mg, 0.7 mmol) were placed in a reaction tube and purged with dry argon. Anhydrous toluene (3 mL) was added and the mixture was heated at 80 °C for 18 h. After cooling to RT, 10 mL of glacial acetic acid and iron powder (279 mg, 5 mmol) were added and the crude product was refluxed for 30 minutes. The acid was removed under reduced pressure, the residue was suspended in saturated sodium bicarbonate solution and extracted with ethyl acetate. The obtained crude product was purified by preparative HPLC to obtain the title compound (58 mg, 73%) as a colorless solid. mp 86-88°C. 1 H NMRδ2.75(t, J=6.9Hz, 2H), 3.24-3.33(m, 2H), 4.33(t, J=7.2Hz, 2H), 7.46-7.50(m, 2H), 7.74-7.86(m ,2H); 13 C NMR δ 23.7, 25.3, 45...
Embodiment 2
[0202] Example 2: 7-methyl-2,3-dihydro-1H-benzo[d]pyrrolo[1,2-a]imidazole
[0203]
[0204] Application of method A to 2-chloro-4-methyl-1-nitrobenzene (86 mg, 0.5 mmol) and pyrrolidin-2-one (51 mg, 0.6 mmol) afforded the title compound (72 mg, 84%) as a viscous oil . 1 H NMR (DMSO) δ 2.73-2.82 (m, 2H), 3.32 (t, J = 7.1Hz), 4.35 (t, J = 7.2Hz, 2H), 7.33 (d, J = 8.3Hz, 1H), 7.57(s, 1H), 7.69(d, J=8.3Hz, 1H); 13 C NMR δ 21.0, 23.8, 25.3, 45.6, 112.5, 114.3, 126.4, 127.1, 135.5, 136.1, 157.8.
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