Asymmetric Synthesis of syn-alpha-Substituted beta-Amino Ketones by Using Sulfinimines and Prochiral Weinreb Amide Enolates

Link: Org Lett ASAP

Franklin A. Davis* and Minsoo Song

Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122

This paper detailed the use of Weinreb amide in stereoselective addition to sulfinimine. Stereoselectivity was controlled by stereochemistry of the sulfinyl group. The major stereochemistry of the product was found to be syn-isomer in excellent ratio.

The most optimal base was found to be LiHMDS in THF, and Et2O in only few cases. Both isomers of the amide products are useful building blocks in a variety of subsequent transformations as seen in schemes below.

As seen in Scheme 5, propyl amide 24 could effectively be used in place of the usual ethyl amide.