Rhodium-mediated cyclopentane construction can compete with .beta.-hydride elimination: synthesis of (.+-.)-tochuinyl acetate
摘要:
Rhodium(II) carboxylate catalyzed C-H insertion to form a cyclopentane is shown to compete effectively with beta-hydride elimination, except when the beta-hydrogen is ternary. Cyclization of diazo ester 27 gives 28, which is converted in three steps to (+/-)-tochuinyl acetate 25. Both the cyclization to form 28 and the alkylation of 28 proceed with remarkable diastereoselectivity.
A New Coupling Reaction of Alkyl Iodides with Electron Deficient Alkenes Using Nickel Boride (cat.)−Borohydride Exchange Resin in Methanol
作者:Tae Bo Sim、Jaesung Choi、Meyoung Ju Joung、Nung Min Yoon
DOI:10.1021/jo961751f
日期:1997.4.1
addition reaction of alkyliodides with alpha,beta-unsaturated esters, nitriles, and ketones proceeds in moderate to excellent yields (50-95%) using Ni(OAc)(2) (0.05-0.2 equiv)-BER (3-5 equiv) in methanol in 1-9 h at room temperature or at 65 degrees C. Nickel boride on borohydride exchange resin (BER) is a good alternative reagent to tributyltin hydride for the coupling of alkyliodides with the electron