Intramolecular Geminal and Vicinal Element Effects in Substitution of Simple Bromo(chloro)alkenes by Methoxide and Thiolate Ions. An Example of a Single Step Substitution?
作者:Michal Beit-Yannai、Zvi Rappoport、Bagrat A. Shainyan、Yuri S. Danilevich
DOI:10.1021/jo9709357
日期:1997.11.1
Intramolecular element effects k(Br)/k(Cl) for substitution of geminal bromochloroalkenes BrC(Cl)=C(Br)Cl (1), BrC(Cl)=CCl(2) (2), Me(2)C=C(Br)Cl (3), and XCH=C(Br)Cl (X = Cl, 4; X = Br, 5), with MeO(-) and RS(-) nucleophiles were investigated. 3 did not give substitution, and 4 and 5 gave substitution with MeO(-) via an initial elimination (to acetylene)-addition route, followed by further reactions
分子内元素效应k(Br)/ k(Cl)替代双溴氯代烯烃BrC(Cl)= C(Br)Cl(1),BrC(Cl)= CCl(2)(2),Me(2)C =研究了C(Br)Cl(3)和XCH = C(Br)Cl(X = Cl,4; X = Br,5),以及MeO(-)和RS(-)亲核试剂。3没有给出取代,而4和5通过最初的消除(至乙炔)加成路线被MeO(-)取代,随后进行了进一步的反应。在4与硫醇盐的反应中,获得2-10的双生元素效应。RSC(Cl)= C(Cl)Y,Y = SR,Br的形成是由于最初的嗜盐反应,随后将RSCl加到形成的乙炔中。2与MeO(-)的反应产生较高的邻位元素效应,而RS(-)产生较高的双生元素效应。1与MeO(-)和RS(-)离子的反应产生了高(2个数量级)的宝石元素效应,其被解释为表明决定速率的CX键裂解。高的k(Br)/ k(Cl)分子间元素效应(k(1)/ k(Cl(2)C