Patent ID: 6559318
Filing Date: 2003-05-06
Classification: C07D

Abstract:
Process for the preparation of (2S, 4R, 9S)-octahydro-1H-indole-2-carboxylic acid, comprising of the following stepsa) reacting a compound of the formula I (R1O)2CHâ€”CH2â€”CH(OR2)2â€ƒâ€ƒI â€ƒwherein R1 and R2 may be the same or different and represent each a C1-4-alkyl group, with water in the presence of an acidic catalyst, b) subjecting the obtained 3,3-dialkylpropionaldehyde of formula II (R1O)2CHâ€”CH2â€”CHOâ€ƒâ€ƒII â€ƒto a Henry-reaction with nitromethane, c) subjecting the obtained 4,4-dialkoxy-1-nitro-4-butanol of formula III (R1O)2CHâ€”CH2â€”CHOHâ€”CH2â€”NO2â€ƒâ€ƒIII â€ƒto a dehydration d) converting the obtained nitroolefin IV with the aid of a Diels-Alder reaction into the corresponding trans-4-(2,2-dialkoxyethyl)-5-nitro-1-cyclohexene V e) hydrogenating the obtained substance V into the corresponding trans-4-(2,2-dialkoxyethyl)-5-amino-1-cyclohexane VI f) subjecting the compound VI to a resolution of racemates and obtaining the (1S, 2R)-1-amino-2-(2,2-dialkoxyethyl)-cyclohexane VII in enantiomerically pure form g) hydrolysing the obtained compound VII to the corresponding aldehyde VIII H) converting the obtained aldehyde into the corresponding nitrile IX by reaction with cyanide ions â€ƒand i) saponifying this nitrile to the (2S, 4R, 9S)-octahydro-1H-indole-2-carboxylic acid.