Modular asymmetric synthesis of functionalized azaspirocycles based on the sulfoximine auxiliary.

A modular asymmetric synthesis of the functionalized azaspirocycles 6 (m = 2, n = 1), 7 (m = 1, n = 2), 8 (m = n = 2), 12, 20, and 24 from the cyclic allylic sulfoximines 1 is described. The synthetic strategy is based on the stereoselective construction of the carbocycle 4 containing the amino-substituted tertiary C atom from 1 followed by the generation of the azaspirocycle. Three different routes have been followed for the synthesis of the heterocyclic ring: N,C-dianion cycloalkylation, ring-closing metathesis, and N-acyl iminium ion formation.