A peculiar transition-metal-free cyclodimerization of propargylic alcohols to vinyl bicyclic ketals
摘要:
Propargylic alcohols, alkylaryl(hetaryl)ethynyl carbinols, under transition-metal-free conditions (KOH/DMSO, 70-80 degrees C, 10-15 min) unexpectedly undergo stereoselective cyclodimerization to 7-methylene-6,8-dioxabicyclo[3.2.1]octanes having the scaffold of known insect pheromones and marine toxins. Under acetylenic pressure the yields of bicyclic ketals reach 80%. In all the cases, the cyclodimers are formed exclusively as one diastereomer. (C) 2011 Elsevier Ltd. All rights reserved.
Improved synthesis of tertiary propargyl alcohols by the Favorskii reaction of alkyl aryl (hetaryl) ketones with acetylene
摘要:
Alkyl aryl (hetaryl) ketones react with acetylene under atmospheric pressure in the superbasic system KOH-EtOH-H2O-DMSO at 10-15A degrees C (2 h) to give the corresponding tertiary propargyl alcohols in up to 91% yield. The procedure requires no large excess of KOH and low-boiling inflammable solvents, produces few wastes, and is safe and convenient on the laboratory scale; there are no limitations for its large-scale application. DOI: 10.1134/S1070428013010028
The transition-metal-free synthesis of sterically congested ethers and heterocycles via the stereospecific etherification and hydroamidation of α-bromocarboxamides and alkynols.
An efficientAu(III)/Ag(I) co-catalytic platform has been established for the synthesis of cyclopentadienes through amine-release annulation of enaminones with alkynes. Vinylcarbenoids that were generated from 1,2-migration of propargyl esters may undergo a tandem annulation process with enaminones to give aminocyclopentenes as key intermediates. The bimetal catalytic system is compatible with a broad
Platinum Catalysed Hydrostannylation of Terminal Alkynes; Highly Selective Synthesis of Vinyl Stannanes
作者:Dean D. Roberts、Mark G. McLaughlin
DOI:10.1002/adsc.202300379
日期:2023.5.23
β-(E)-vinyl stannane. The catalyst system is able to provide the corresponding vinyl stannane in selectivities which surpasses that which is typically afforded under palladium catalysis. Additionally, a telescoped hydrometallation/cross-coupling sequence has been developed, allowing for application of the vinyl stannanes without excessive manipulation or purification of the intermediate stannane.
fluorinated alkene synthesis using easily accessible and modular thianthrenium salts with electron-withdrawing alkynes or propargyl alcohols is reported. Vinyl radical intermediates, formed by the reaction between the alkyl or trifluoromethyl thianthrenium salts and electronically diverse alkynes, can mediate the key 1,5-HAT process of regioselective C(sp3)–H fluorination and vinylation. This protocol