Regio- and Stereoselective Aminopentadienylation of Carbonyl Compounds

Abstract

A simple and robust protocol is detailed for the preparation of enantioenriched alpha-substituted (1,4-pentadien-3-yl)amine derivatives. The methodology involves the addition of an in situ formed pentadienyl indium reagent to chiral tert-butylsulfinimines, previously formed in the same pot. The addition takes place with excellent gamma-regio- and diastereoselectivity for a wide range of carbonyl compounds, including alpha-unsubstituted aldehydes and methyl alkyl ketones. The catalytic hydrogenation of the sulfinamines obtained provides a convenient access to chiral alpha-substituted (3-pentyl)amines. The hydroboration-oxidation of the alpha-(1,4-pentadien-3-yl)amine derivatives, followed by a cyclization under Mitsunobu conditions, takes place with an excellent diastereoselectivity governed by the chiral sulfinyl group.