Process Improvements for the Preparation of Kilo Quantities of a Series of Isoindoline Compounds

A series of isoindoline analogues with either an indazole (HMR 2934, HMR 2651) or benzisoxazole (HMR 2543) appendage were prepared for the proposed treatment of psychiatric disorders such as obsessive compulsive disorder and attention deficit disorder. The isoindoline compounds were prepared by reduction of the corresponding phthalimides with LiAlH 4 . One compound was not chiral, and the other two required an enantioselective synthesis. The key step for these optically active analogues involved the coupling by an S N 2 process of either a piperazynyl intermediate or a piperdinyl intermediate with methyl 3-benzyloxy-2-trifluoromethansulfonatopropionate. The products for these two analogues had >98% ee. Process improvements led to the multi-kilogram syntheses of each of these compounds.