A one-pot, reductive amination/6-endo-trig cyclisation for the stereoselective synthesis of 6-substituted-4-oxopipecolic acids.

The first stereoselective synthesis of 2,6-trans-6-substituted-4-oxo-L-pipecolic acids using a tandem reductive amination/6-endo-trig cyclisation process is described. The sequential reduction and cyclisation mediated by sodium cyanoborohydride allowed the preparation of a series of highly functionalised 6-alkyl and 6-aryl analogues. This journal is © The Royal Society of Chemistry 2011