for the preparation of 3-substituted isocoumarins via palladium-catalyzed nucleophilic addition/oxidative annulation of bromoalkynes with benzoic acids has been developed. Remarkably, preliminary mechanistic studies indicated that the transformation might proceed via a stereo- and regioselective nucleophilic addition and C–H functionalization procedure.
A new reaction of 1-bromoalk-1-ynes; synthesis of 3-alkylalk-1-ynes from terminal acetylenes
作者:Augustus J. Quillinan、Ejaz A. Khan、Feodor Scheinmann
DOI:10.1039/c39740001030
日期:——
The reaction of 1-bromoalk-1-ynes with two equivalents of butyl-lithium in hexane gives 3-butylalk-1-ynes; the reactive intermediate is a dilithioalkyne which can also be directly prepared fromterminalacetylenes, and selective reaction with alkyl halides in hexane occurs at the propargylic site to provide a general synthesis of 3-alkylalk-1-ynes.
Copper-Catalyzed Stereospecific Transformations of Alkylboronic Esters
作者:Ningxin Xu、Hao Liang、James P. Morken
DOI:10.1021/jacs.2c04037
日期:2022.7.6
followed by coupling with alkynyl bromides, allyl halides, propargylic halides, β-haloenones, hydroxylamine esters, and acyl chlorides. Through this simple transformation, commercially available inexpensive compounds can be employed to convert primary and secondary alkylboronic esters to a wide array of synthetically useful compounds.
Enantioselective Construction of Carbocyclic and Heterocyclic Tertiary Boronic Esters by Conjunctive Cross-Coupling Reaction
作者:Xuntong Zhang、Chenpeng Gao、James P. Morken
DOI:10.1021/jacs.3c05815
日期:2023.8.2
Synthesis of stereodefined carbocyclic and heterocyclic tertiary boronic esters is accomplished by performing a conjunctive cross-couplingreaction on preformed cyclic boron ate complexes. Boronates bearing spirocyclic and aryl bicyclic skeletons can be synthesized enantioselectively using a chiral PHOX-ligated Pd catalyst with achiral starting material, while substrates bearing continuous stereogenic
An enantioselective difunctionalization of activated alkynes using chiral sulfinamide reagents is developed. It is an atom and chirality transfer process that allows for the modular synthesis of optically active α-aminoacidderivatives under mild conditions. The reaction proceeds through an acid-catalyzed [2,3]-sigmatropic rearrangement mechanism with predictable stereochemistry and a broad scope