Patent ID: 6884893

Claim:
A process for the selective cleavage of a cycloanhydride of the formula I in which A is benzyl, alkyl having from 1 to 6 carbon atoms or aryl, to give a corresponding monoester, comprising reacting the compound of the formula I a) with a chiral aminoalcohol of the general formula II in which X 1 and X 2 are each R or OH, with the proviso that X 1 is not the same as X 2 , and one of the two radicals is OH, R, R 1 and R 2 are each, independently, H, alkyl having 1-12 carbon atoms, unsubstituted or substituted cycloalkyl having 3-8 carbon atoms, alkenyl, aryl, or arylalkyl, and where the substituents may be alkyl, alkenyl, alkoxy, aryl, aryloxy, or dialkylamine with the proviso that at least one of the radicals R, R 1 and R 2 is an unsubstituted or substituted cycloalkyl, or alkenyl, R 3 and R 4 are each alkyl having 1-12 carbon atoms, unsubstituted or substituted cycloalkyl having 3-8 carbon atoms, alkenyl, aryl, or arylalkyl, with the possible substituents described for R, in an inert solvent, or b) with a chiral aminoalcohol of the general formula III in which X 1 and X 2 are each R′ or OH, with the proviso that X 1 is not the same as X 2 , and one of the two radicals is OH, R′, R 5 and R 6 are each H, alkyl having 1-12 carbon atoms or aryl, which may be substituted by alkyl or alkoxy, and R 7 and R 8 are each alkyl having 1-12 carbon atoms or aryl, which may be substituted by alkyl or alkoxy, in toluene, benzene or xylene at a temperature of from 15° to 35° C., in high selectivity to give a diastereomer, and optionally subsequently reducing the monoester using boron hydride, and then closing the ring to give the corresponding lactone.