A syn-Selective Aza-Aldol Reaction of Boron Aza-Enolates Generated from N-Sulfonyl-1,2,3-Triazoles and 9-BBN-H

A syn‐selective aza‐aldol reaction of boron aza‐enolates, generated from N‐sulfonyl‐1,2,3‐triazoles and 9‐BBN‐H, is reported. It provides a sequential one‐pot procedure for the stereoselective construction of 1,3‐amino alcohols, having contiguous stereocenters, starting from terminal alkynes. All fours: N‐Sulfonyl‐1,2,3‐triazoles react with 9‐BBN‐H in the presence of a rhodium(II) catalyst to produce E isomers of boron aza‐enolates, which sequentially undergo aza‐aldol reactions with aldehydes to form syn aza‐aldol products. This method is successfully run as a four‐step one‐pot reaction for the stereoselective construction of 1,3‐amino alcohols starting from terminal alkynes.