Sodium cyanoborohydride → 4-Aminopyran-4-yl carboxylic acid t-butyl ester

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Reaction Steps

An alternative route for the preparation of some 1,3,4-trisubstituted cyclopentanes within the scope of the instant invention is given in Scheme 11. Reductive alkylation, using for example sodium triacetoxyborohydride or sodium cyanoborohydride, of a cycloalkyl amino-acid 11-2, such as 1-aminocyclopentane carboxylic acid t-butyl ester (Z=single bond) or a heterocyclic amino-acid, such as 4-aminopyran-4-yl carboxylic acid t-butyl ester (Z=O) with the ketone-alcohol 11-1 (Scheme 4) gives 11-3 and 11-4 as a mixture of C-1 isomers which may be separated. These intermediates can then be converted to the final product(s) 11-5 and/or 11-6 as described in Scheme 5.

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