Regio- and stereoselective lithiation of terminal oxazolinylaziridines: the aziridine N-substituent and the oxazolinyl group effect.
The regioselective lithiation of terminal oxazolinylaziridines has been investigated. The steric hindrance of the nitrogen substituent in 1-trityl-2-oxazolinylaziridine 3a, combined with the coordinating ability of the oxazolinyl group, causes beta-lithiation, whereas a completely regioselective alpha-lithiation is observed with the much less sterically demanding 1-benzyl-2-oxazolinylaziridine 3c and a competition between alpha- and beta-lithiation occurs with 1-cumyl-2-oxazolinylaziridine 3b in which the N-substituent has a steric hindrance in between the trityl and the benzyl groups. The application of the lithiation-trapping sequence for the preparation of enantioenriched 2,3-cis-disubstituted oxazolinylaziridines and aziridino-gamma-lactones is also reported.
Luisi
Renzo
R
Dipartimento Farmaco-Chimico, Università di Bari, Consorzio Interuniversitario Nazionale Metodologie e Processi Innovativi di Sintesi C.I.N.M.P.I.S., Via E. Orabona 4, I-70125 Bari, Italy.
Capriati
Vito
V
Di Cunto
Peppino
P
Florio
Saverio
S
Mansueto
Rosmara
R
D001388:Aziridines / Q000737:chemistry*; D007783:Lactones / Q000737:chemistry; D008094:Lithium / Q000737:chemistry*; D010080:Oxazoles / Q000737:chemistry; D013237:Stereoisomerism
D001388:Aziridines; D007783:Lactones; D010080:Oxazoles; D008094:Lithium