N-Heterocyclic carbenes promote the formal [2+2] cycloaddition of ketenes with N-tosyl imines to give the corresponding β-lactams in good to excellent isolated yields; chiral NHCs give β-lactams in high e.e. after crystallisation.
N-杂环卡宾促进了酮烯与N-托烯
亚胺的形式[2+2]环加成反应,得到相应的β-内酯,收率在良好到优良范围内;手性NHC在结晶后给予高光学纯度的β-内酯。