The reaction between primary amines and 2-bromo-2-(cycloalkylidene)acetates in alcohol under high pressure provides the expected spiroaziridines in good yields and diastereomeric excesses. With bulky or aromatic amines, this reaction competes with the migration of the double bond, which, migrating from an exo to an endocyclic position, provides an intermediate allylic α-bromo ester, immediately converted into an α-amino ester. It was also possible to develop a tandem version, applying the same high pressure conditions to a 1,4-bis-cyclohexylidene acetate. The corresponding bis-spiroaziridine was obtained in good yield and moderate de. However, this reaction did not succeed with 2-chloro-2-(cyclopropylidene)acetate, which produced only glutaric acid derivatives in low yields.
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Rulev et al. (2001) studied this question.