A novel strategy involving Cu‐catalyzedoxidative transformation of ketone‐derived hydrazone moiety to various synthetic valuable internal alkynes and diynes has been developed. This method features inexpensive metal catalyst, green oxidant, good functional group tolerance, high regioselectivity and readily available starting materials. Oxidative deprotonation reactions were carried out to form internal
An efficient synthesis of (E)‐alken‐1,2,3‐triboronates form readily available propargylic carbonates is described. The reaction enjoys excellent regio‐ and E‐selectivity and many synthetically useful functional groups can be tolerated. Based on mechanistic studies, a two‐step mechanism via 1,2‐allenyl boronate intermediate is proposed.
[(RCN)2PdCl2]-Catalyzed E/Z Isomerization of Alkenes: A Non-Hydride Binuclear Addition-Elimination Pathway
作者:Emily H. P. Tan、Guy C. Lloyd-Jones、Jeremy N. Harvey、Alastair J. J. Lennox、Benjamin M. Mills
DOI:10.1002/anie.201103947
日期:2011.10.4
A crepuscular catalyst: Alkene migration catalyzed by [(RCN)2PdCl2] complexes proceeds through an in situ generated Pd‐H species. Addition of a 1,5‐diene inhibits migration and allows the slower background catalysis of E/Z interconversion to be studied. Experimental and computational results suggest this interconversion proceeds through a conformational equilibrium in dipalladacycles (see picture)
two‐carbon (C2) cyclization buildingblock. The present protocol successfully inhibits the competitive cycloaddition with the C≡N bond of acetonitrile, but enables the in situ formation of an unsaturated carbon–carbonbond and the subsequent cycloaddition as a C2 unit. This chemistry features simple reaction conditions, high chemoselectivities, wide substrate scope, and offers a new and practical approach
Directed Regioselective Carbometallation of 1,2‐Dialkyl‐Substituted Cyclopropenes
作者:Yair Cohen、Ilan Marek
DOI:10.1002/anie.202111382
日期:2021.12.6
The copper-catalyzedcarbomagnesiation reaction of cyclopropenes is a well-established method for the synthesis of stereodefined cyclopropanes. All existing reports to date proceeded towards the formation of the electronically more stable organometallic intermediate. Herein we report a regioselective addition to 1,2-dialkyl-substituted cyclopropene possessing a tethered directing group to direct the