title: [3 + 1]- and [3 + 2]-Cycloadditions of Azaoxyallyl Cations and Sulfur Ylides.
abstract: A new formal [3 + 1]-cycloaddition reaction of azaoxyallyl cation intermediates, generated in situ from α-halo hydroxamates bearing α-alkyl groups, and sulfur ylides is reported, furnishing useful β-lactams (dr >19:1) in fair to modest yields. In contrast, an unexpected formal [3 + 2]-cycloaddition reaction occurs to give γ-lactam derivatives for α-halo hydroxamates with α-aryl groups and sulfur ylides in the presence of bases.
authors.affiliation: College of Pharmacy, Third Military Medical University , Shapingba, Chongqing 400038, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Li
authors.affiliation: College of Pharmacy, Third Military Medical University , Shapingba, Chongqing 400038, China.
authors.forename: Kun
authors.initials: K
authors.lastname: Jiang
authors.affiliation: College of Pharmacy, Third Military Medical University , Shapingba, Chongqing 400038, China.
authors.forename: Qin
authors.initials: Q
authors.lastname: Ouyang
authors.affiliation: College of Pharmacy, Third Military Medical University , Shapingba, Chongqing 400038, China.
authors.forename: Tian-Yu
authors.initials: TY
authors.lastname: Liu
authors.affiliation: College of Pharmacy, Third Military Medical University , Shapingba, Chongqing 400038, China.|Key Laboratory of Drug-Targeting and Drug Delivery System of the Ministry of Education, West China School of Pharmacy, Sichuan University , Chengdu 610041, China.
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Chen