Synthesis of homochiral propargyl amines from N-(Boc)-tetrahydro-2H-1,3-oxazines

Abstract

The functionalisation of homochiral N-(Boc)-tetrahydro-2H-1,3-oxazines with the Grignard reagent of (trimethylsilyl)acetylene under Lewis acidic conditions is described. This leads directly to homochiral propargyl amines in good yields, under mild conditions, and with moderate to good enantioselectivities. The stereochemistry of the major enantiomer was determined to be (R) by correlation, and a mechanism for the ring opening reaction has been proposed on this basis.