Highly Stereoselective Synthesis of Optically Active Oxazolinyl Oxiranes from Azaenolates of a Chiral 2-Chloromethyloxazoline

Boron and titanium azaenolates 2 and 4, generated at 0°C and -100°C, respectively, from the optically active chloromethyloxazoline 1, have been found to couple with aliphatic ketones in a highly diastereoselective fashion ending up with the formation of optically active oxazolinyl oxiranes 3. Less stereoselective was the reaction with aromatic ketones