Preparation method of (3R,5R)-3,5-dihydroxy-6-methyl cyan-caproate
A technology of cyanocaproate and dihydroxy, applied in the field of preparation of -3, 5-dihydroxy-6-cyanocaproate, which can solve the problems of complex operation, harsh reaction conditions, high equipment and labor protection requirements , to achieve high yield, mild reaction conditions and good industrialization prospects
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Embodiment 1
[0028] Step 1: Preparation of (R)-3-tert-butyldiphenylsilyloxy-5-methoxy-5-oxopentanoic acid ( )
[0029] 3--tert-butyldiphenylsilyloxycyclopentanoic anhydride ( )1.1 g (3 mmol, 1.0 eq), methanol 1.2 mL (30 mmol, 10 eq), quinine thiourea catalyst 0.3 mmol (0.1 eq) dissolved in 150 mL methyl tert-butyl ether, 0 o C was reacted for 24 hours, concentrated under reduced pressure, and purified by column chromatography to obtain colorless oily matter 3-tert-butyldiphenylsilyloxy-5-methoxy-5-oxopentanoic acid ( ) (1.16 g, 2.9 mmol), 97% yield. 1 H-NMR (400 MHz, CDCl 3 ) δ 1.04 (s, 9H), 2.55-2.68 (m, 4H), 3.57 (s, 3H), 4.50-4.56 (m, 1H), 7.36-7.47 (m, 6H), 7.68 (d, J = 6.8 Hz, 4H), 10.07 (br s, 1H) ppm. MS (ESI): 399 (M-H + );
[0030] Step 2: Preparation of (R)-dimethyl 2-cyano-3-oxo-5-tert-butyldiphenylsiloxypimelate ( )
[0031] 3-tert-butyldiphenylsilyloxy-5-methoxy-5-oxopentanoic acid ( ) 800 mg (2 mmol, 1.0 eq), 0.29 mL (3 mmol, 1.5 eq) of oxalyl chloride, ...
Embodiment 2
[0037] Step 1: Preparation of (R)-3-tert-butyldiphenylsilyloxy-5-benzyloxy-5-oxopentanoic acid ( )
[0038] 3-tert-butyldiphenylsilyloxycyclopentanoic anhydride ( ) 1.1 g (3 mmol, 1.0 eq), 3.1 mL (30 mmol, 10 eq) of benzyl alcohol, and 0.3 mmol (0.1 eq) of quinine sulfonamide catalyst were dissolved in 150 mL of tetrahydrofuran, and reacted at room temperature for 12 hours under a nitrogen atmosphere. Concentrate under reduced pressure, and purify by column chromatography to obtain colorless oil 3-tert-butyldiphenylsilyloxy-5-benzyloxy-5-oxopentanoic acid ( ) (1.4 g, 2.9 mmol), 97% yield. 1 H-NMR (400 MHz, CDCl 3 ) δ: 1.01 (s, 9H), 2.54-2.69 (m, 4H), 4.49-4.55 (m, 1H), 4.97 (d, J = 12.0 Hz, 1H), 5.03 (d, J = 12.0 Hz, 1H), 7.25-7.44 (m, 11H), 7.64-7.67 (m, 4H) ppm. MS (ESI): 477 (M+H + );
[0039] Step 2: Preparation of methylbenzyl (R)-2-cyano-3-oxo-5-tert-butyldiphenylsiloxypimelate ( )
[0040] 3-tert-butyldiphenylsilyloxy-5-benzyloxy-5-oxopentanoic acid...
Embodiment 3
[0046] Step 1: Preparation of (R)-3-tert-butyldimethylsilyloxy-5-methoxy-5-oxopentanoic acid ( )
[0047] 3-tert-butyldimethylsiloxycyclopentanoic anhydride ( ) 0.73 g (3 mmol, 1.0 eq), 1.2 mL (30 mmol, 10 eq) of methanol, and 0.3 mmol (0.1 eq) of quinine urea catalyst were dissolved in 150 mL of dichloromethane, and reacted at room temperature for 12 hours under a nitrogen atmosphere. Concentrate under reduced pressure, and purify by column chromatography to obtain 3-tert-butyldimethylsilyloxy-5-methoxy-5-oxopentanoic acid as a colorless oil ( ) (0.8 g, 2.9 mmol), yield 97%. 1 H-NMR (400 MHz, CDCl 3 ) δ 0.06 (s, 3H), 0.07 (s, 3H), 0.84 (s, 9H), 2.55-2.69 (m, 4H), 3.68 (s, 3H), 4.51-4.57 (m, 1H), 11.07 ( br s, 1H) ppm. MS (ESI): 275 (M-H + );
[0048] Step 2: Preparation of dimethyl (R)-2-cyano-3-oxo-5-tert-butyldimethylsiloxypimelate ( )
[0049] 3-tert-butyldimethylsilyloxy-5-methoxy-5-oxopentanoic acid ( ) 552 mg (2 mmol, 1.0 eq), 0.29 mL (3 mmol, 1.5 ...
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