title: Radical migration-addition of N-tert-butanesulfinyl imines with organozinc reagents.
abstract: A novel migration-addition sequence was discovered for the reaction of enantioenriched N-tert-butanesulfinyl iminoacetate 1a with functionalized benzylzinc bromide reagents, producing tert-leucine derivatives in excellent diastereoselectivity (dr 98:2). The absolute configurations of two new chiral centers were unambiguously assigned by chemical transformations and X-ray crystallography. In addition, the regio- and diastereoselectivities of this novel reaction were both explained through the key N-sulfinamine intermediate M6 generated by the tert-butyl radical attack on the imine. Computational analysis of this reaction process, which was performed at the B3LYP/6-311++G(3df,2p)//B3LYP/6-31G*-LANL2DZ level, also supported our proposed two-stage mechanism.
authors.affiliation: Department of Chemistry and Institutes of Biomedical Sciences, Fudan University , 220 Handan Road, Shanghai 200433, China.
authors.forename: Wei
authors.initials: W
authors.lastname: Huang
authors.forename: Jian-Liang
authors.initials: JL
authors.lastname: Ye
authors.forename: Wei
authors.initials: W
authors.lastname: Zheng
authors.forename: Han-Qing
authors.initials: HQ
authors.lastname: Dong
authors.forename: Bang-Guo
authors.initials: BG
authors.lastname: Wei
mesh_terms: D018360:Crystallography, X-Ray; D005609:Free Radicals / Q000138:chemical synthesis / Q000737:chemistry; D007930:Leucine / Q000031:analogs & derivatives; D008958:Models, Molecular; D008968:Molecular Conformation; D009942:Organometallic Compounds / Q000737:chemistry*; D011789:Quantum Theory; D013237:Stereoisomerism; D013452:Sulfonium Compounds / Q000737:chemistry*; D014633:Valine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D015032:Zinc / Q000737:chemistry*
chemical_list: D005609:Free Radicals; C481933:N-tert-butanesulfinylimino ester; D009942:Organometallic Compounds; D013452:Sulfonium Compounds; C089871:2-amino-3,3-dimethylbutanoic acid; D007930:Leucine; D014633:Valine; D015032:Zinc