Asymmetric Methods for Radical Addition to Imino Compounds

Asymmetric Methods for Radical Addition to Imino Compounds 

Chiral Amine Synthesis Methods, Developments and Applications. Edited by Thomas C. Nugent Copyright 2010 WILEY-VCH Verlag GmbH Co. KGaA. Weinheim ISBN 978-3.527-32509-2 

Intermolecular Radical Addition Chiral N-Acyl hydrazo nes 

We regarded hydrazones as potentially superior radical acceptors they offer reactivity enhancement similar to that of oxime ethers, and the additional valence of the nitrogen (versus the oxygen of an oxime) could facilitate the conformational constraints that had been missing from oxime ethers. While F/Zmixtures complicate the use of oxime ethers, aldehyde hydrazones generally adopt C=N E geometry. If 

The assumption of an early transition state for radical addition enables the ground state structure to serve as a reasonable approximation of the transition state geom etry. With this in mind, we hypothesized that steric blocking of one of the enantio topic approach trajectories by a substituent above or below the plane of hydrazone C=N bond should lead to an enantioselective process. 

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