Synthesis of Alkynyl Ethers and Low-Temperature Sigmatropic Rearrangement of Allyl and Benzyl Alkynyl Ethers
作者:Juan R. Sosa、Armen A. Tudjarian、Thomas G. Minehan
DOI:10.1021/ol802147h
日期:2008.11.6
transformed into 1-alkynyl ethers 5 by a two-step procedure involving formation of the enol triflate or phosphate and base-induced elimination. Performing the same reaction sequence with allylic alcohols (R2OH, R2 = allyl) furnishes instead gamma,delta-unsaturated carboxylic acid derivatives 6, derived from [3,3]-sigmatropic rearrangement of the intermediate allyl alkynyl ethers at -78 degrees C and trapping
Dirhodium(ii)-catalyzed formal [3+2+1]-annulation of azomethine imines with two molecules of a diazo ketone
作者:Xinfang Xu、Xichen Xu、Peter Y. Zavalij、Michael P. Doyle
DOI:10.1039/c3cc41119b
日期:——
A highly diastereoselective formal [3+2+1]-cycloaddition reaction that produces multi-functionalized bicyclic pyrazolidinone derivatives is achieved in moderate to high yield by Rh2(4S-MPPIM)4-catalyzed reaction of azomethine imines with two molecules of a diazo ketone.
A highly enantioselective four-component reaction for the efficient construction of chiral β-hydroxy-α-amino acid derivatives
作者:Yu Qian、Changcheng Jing、Shunying Liu、Wenhao Hu
DOI:10.1039/c3cc40546j
日期:——
An enantioselective four-componentreaction of a diazoketone, water, an aniline and ethyl glyoxylate in the presence of catalytic Rh2(OAc)4 and a chiral Bronsted acid was developed to efficiently produce beta-hydroxy-alpha-amino acid derivatives in good yields with high diastereoselectivity and enantioselectivity.