The Ketene-Surrogate Coupling: Catalytic Conversion of Aryl Iodides into Aryl Ketenes through Ynol Ethers
作者:Wenhan Zhang、Joseph M. Ready
DOI:10.1002/anie.201405036
日期:2014.8.18
tert‐Butoxyacetylene is shown to undergo Sonogashira coupling with aryliodides to yield aryl‐substituted tert‐butyl ynol ethers. These intermediates participate in a [1,5]‐hydride shift, which results in the extrusion of isobutylene and the generation of aryl ketenes. The ketenes are trapped in situ with multiple nucleophiles or undergo electrocyclic ring closure to yield hydroxynaphthalenes and quinolines
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
Synthesis of Eight‐Membered Lactams through Formal [6+2] Cyclization of Siloxy Alkynes and Vinylazetidines
作者:An Wu、Qiang Feng、Herman H. Y. Sung、Ian D. Williams、Jianwei Sun
DOI:10.1002/anie.201902866
日期:2019.5.13
lactams through formal [6+2] cyclization of siloxyalkynes and vinylazetidines has been developed. Evidence from a chirality transfer experiment suggests that the reaction proceeds via a [3,3]‐sigmatropic rearrangement from a ketene intermediate. This insight led to the development of alternative conditions and use of acyl chlorides as ketene precursors for the [6+2] reaction with vinylazetidines.
Synthesis of Alkyl-Ynol-Ethers by “Anti-Michael Addition” of Metal Alkoxides to β-Substituted Alkynylsulfones
作者:Leyre Marzo、Alejandro Parra、María Frías、José Alemán、José Luis García Ruano
DOI:10.1002/ejoc.201300395
日期:2013.7
alkoxides with β-substituted 2-(p-tolylsulfonyl)acetylenes, involving an anti-Michael addition reaction followed by the in situ elimination of the sulfonyl moiety, provides a direct method for the synthesis of alkyl alkynyl ethers bearing aryl or TIPS groups joined to the triple bond. Arylalkynyl ethers derived from primary alkoxides are in situ hydrolyzed into arylacetic esters.
An Approach to a 2-Hydroxy-3-phenyldibenzofuran Skeleton Based on Rh(PPh3)3Cl-Catalyzed [2+2+2] Cycloaddition between a 1-Ethynyl-2-(ethynyloxy)benzene and an (Alkoxyethynyl)benzene
A Rh(PPh3)(3)Cl-catalyzed [2+2+2] cycloaddition of a 2-(trimethyl-silylethyny1)-1-(ethynyloxy)benzene derivative (a 1,6-diyne unit) with an (alkoxyethynyl)benzene (an alkoxyacetylene unit) was studied for the construction of the 2-hydroxy-3-phenyldibenzofuran skeleton of kehokorin E. Although the dimerization of the 1,6-diyne unit was a serious problem in the initial trial, installation of a bulky substituent at the terminal of the ethynyloxy group of the 1,6-diyne unit was found to inhibit the dimerization to produce cycloadducts in good yield. It was also found that the use of a 2-hydroxypropan-2-yl group as the bulky group increased the ratio of the desired 2-alkoxy-3-phenyldibenzofuran isomer to a 3-alkoxy-2-phenyldibenzofuran isomer.