is presented. The procedure requires the easily available terminal alkynes as starting materials as well as commercially and readily available reagents such as diethylthiophosphite. The experimental procedure consists of a one‐pot process without any slow addition of one of the reagents.
method for cyclization of alkynes is described. The reaction cascade involves the intermolecular addition of a phenylthiyl radical to a terminal triple bond generating an alkenylradical, followed by a 1,5-hydrogen atom transfer and a 5-exo-trig radicalcyclization. This very efficient tin-free procedure allows one to prepare highly functionalized cyclopentane derivatives as well as fused bicyclic and
Iodine atom transfer addition reactions with alkynes. Part 2; α-iodocarbonyls
作者:Dennis P. Curran、Dooseop Kim、Carl Ziegler
DOI:10.1016/s0040-4020(01)86551-0
日期:1991.8
1°-Iodo esters, ketones, and nitriles react smoothly in atom transfer addition reactions with alkyl- substituted (nucleophilic) alkynes, but a 3°-iodoester prefers to add to ester-substituted (electrophilic) alkynes. These atom transfer additions are suited for preparing precursors for radical translocation reactions as well for appending β- lactam side chains.
Thiophenol-Mediated Hydrogen Atom Abstraction: An Efficient Tin-Free Procedure for the Preparation of Cyclopentane Derivatives
作者:Florent Beaufils、Fabrice Dénès、Philippe Renaud
DOI:10.1021/ol049162g
日期:2004.7.1
[reaction: see text] An efficient procedure for running a cascade reaction involving 1,5-abstraction of a hydrogenatom followed by a radical cyclization is reported. Alkenyl radicals are generated from easily available terminal alkynes and thiophenol. This procedure eliminates the need of using the toxic tributyltin hydride and gives a greater amount of radical translocation products.
A gold(I)-catalyzed cycloisomerization/ring expansion sequence allows the highly enantioselective synthesis of 2-oxocyclobutylcyclopentane derivatives from cyclopropyl-substituted enynes. The bimetallic [(R)-MeO-DTBM-BIPHEP-(AuCl)2] complex was found to be the best precatalyst, affording the desired cyclobutanones in high yields and enantioselectivities (up to 99% ee). The usefulness of the method