On the lithiation of oxazolinylaziridines

Lithiated N-sulfonyloxazolinylaziridines 6a and 7a, generated by deprotonation of the corresponding aziridines 6 and 7 with sec-BuLi/TMEDA at −98°C in THF, were found to be chemically and configurationally stable to be stereospecifically captured by electrophiles, while warming up to rt resulted in the formation of oxazolinylazirine 15. In contrast, lithiation of N-phenyloxazolinylaziridines 8 and 9 led to oxazolinylenamine 18. Tricyclic aziridines 10 and 11 resulted from an intramolecular addition of the aziridinyllithium 6a to the phenyl ring of the benzenesulfonyl group.