title: Enantioselective synthesis of aza-beta-lactams via NHC-catalyzed [2 + 2] cycloaddition of ketenes with diazenedicarboxylates.
abstract: N-Heterocyclic carbenes were found to be efficient catalysts for the formal [2 + 2] cycloaddition of aryl(alkyl)ketenes and diazenedicarboxylates to give the corresponding aza-beta-lactams in good yields with up to 91% ee. The N-substituent (carboxylate vs benzoyl) of diazenes played an important role to control the reaction modes (formal [2 + 2] vs [4 + 2] cycloaddtions).
authors.affiliation: Beijing National Laboratory for Molecular Sciences, CAS Key Laboratory of Molecular Recognition and Function, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100190, China.
authors.forename: Xue-Liang
authors.initials: XL
authors.lastname: Huang
authors.forename: Xiang-Yu
authors.initials: XY
authors.lastname: Chen
authors.forename: Song
authors.initials: S
authors.lastname: Ye
mesh_terms: D002384:Catalysis; D003500:Cyclization; D003998:Dicarboxylic Acids / Q000737:chemistry*; D005030:Ethylenes / Q000737:chemistry*; D006571:Heterocyclic Compounds / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D008697:Methane / Q000031:analogs & derivatives* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism; D047090:beta-Lactams / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D003998:Dicarboxylic Acids; D005030:Ethylenes; D006571:Heterocyclic Compounds; D007659:Ketones; D047090:beta-Lactams; C030011:carbene; C008223:ketene; D008697:Methane