On the coupling reaction of lithium azaenolates of chiral oxazolines with carbonyl compounds

Optically pure chloromethyloxazolines have been prepared, lithiated and then reacted with benzophenone to furnish stereoselectively oxazolinyl oxiranes and formyl oxiranes. The stereoselection observed has been related to the geometry of the intermediate lithium azaenolates. Calculations have been carried out in order to evaluate the relative stability of the E and Z forms of the lithium azaenolates. The reaction of a lithium azaenolate with other ketones leading to oxazolinyl epoxides is also reported.