Highly Diastereo- and Enantioselective Synthesis of alpha-Spiro-delta-lactams by an Organocascade Reaction
2017
Abstract
An asymmetric synthesis of alpha-spiro-delta-lactams by an organocascade reaction of easily accessible starting materials has been accomplished. The catalytic sequence begins with enantioselective Michael addition of a beta-ketoamide to an a, alpha,beta-unsaturated aldehyde, catalyzed by a secondary amine catalyst, and is followed by hemiaminal annulation.
Optically enantiopure compounds with three stereogenic centres are obtained in good yields and excellent selectivities (up to > 20:1 dr and up to > 99 % ee).