[CH2:1](SCC=O)[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.C(N)(=[O:14])C.C(NC=CSCC1C=CC=CC=1)(=O)C.[CH3:30][C@@H:31]1[CH2:36][C@H:35]([OH:37])[C@@H:34]([CH:38]([CH3:40])[CH3:39])[CH2:33][CH2:32]1>Cl[Pd](Cl)([P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1)[P](C1C=CC=CC=1)(C1C=CC=CC=1)C1C=CC=CC=1.C1COCC1>[CH2:1]([OH:14])[C:2]1[CH:7]=[CH:6][CH:5]=[CH:4][CH:3]=1.[CH3:30][C@@H:31]1[CH2:36][C@H:35]([OH:37])[C@@H:34]([CH:38]([CH3:40])[CH3:39])[CH2:33][CH2:32]10.10 mol of 2-(benzylthio)acetaldehyde and 0.20 mol of acetamide are heated together at 100° C. with stirring, and the product solid is heated in a sublimator at 250° C. and 1 mm Hg until formation of the enamide 1-acetamido-2-benzylthioethene is complete. A 70 mL stainless steel high pressure reactor fitted with a Pyrex glass liner and magnetic stir bar is charged with THF (5 mL), D-menthol (0.5 mmol), (PPh3)2PdCl2 (36 mg, 0.05 mmol), and 1-acetamido-2-benzylthioethene (0.5 mmol). The reactor is sealed, pressurized to 1000 psig with CO, and stirred for 24 hours at 100° C. The product mixture, isolated after removal of gas from the reactor vessel, contains a mixture of two diastereomeric cysteine derivatives, N-acetyl-L-benzylcysteine D-menthyl ester and N-acetyl-D-benzylcysteine D-menthyl ester. These diastereomers are separated by column chromatography on silica gel with benzene-ethyl acetate eluent and are separately hydrolyzed by heating to 100° C. in 1N HCl for 2 hours to give pure L- and D-cysteine, benzyl alcohol, acetic acid, and D-menthol, which is thereafter recycled to a repeat of the foregoing hydrocarboxylation reaction.
불러오는 중…
