Luisi Renzo, Capriati Vito, Di Cunto Peppino, Florio Saverio, Mansueto Rosmara
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.
Org Lett. 2007 Aug 16;9(17):3295-8. doi: 10.1021/ol071264u. Epub 2007 Jul 26.
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.
对末端恶唑啉基氮丙啶的区域选择性锂化反应进行了研究。1-三苯甲基-2-恶唑啉基氮丙啶3a中氮取代基的空间位阻，与恶唑啉基的配位能力相结合，导致β-锂化，而对于空间位阻小得多的1-苄基-2-恶唑啉基氮丙啶3c则观察到完全区域选择性的α-锂化，并且在1-枯基-2-恶唑啉基氮丙啶3b中发生α-锂化和β-锂化之间的竞争，其中N-取代基的空间位阻介于三苯甲基和苄基之间。还报道了锂化-捕获序列在制备对映体富集的2,3-顺式二取代恶唑啉基氮丙啶和氮丙啶基-γ-内酯中的应用。
