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

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