Synergistic Catalysis: Enantioselective Ring Expansion of Vinyl Cyclopropanes Combining Four Catalytic Cycles for the Synthesis of Highly Substituted Spirocyclopentanes Bearing up to Four Stereocenters
作者:Marta Meazza、Ramon Rios
DOI:10.1002/chem.201601893
日期:2016.7.11
A double synergistic cascade reaction is reported, combining transition metal and amine catalysis. The reaction between vinyl cyclopropanes and enals renders the final cyclopentane derivatives in excellent yields and stereoselectivities.
This paper is dedicated to Professor Dieter Enders on the occasion of his70thbirthday. He has always been a source of inspiration to develop new cascade reactions. Abstract We present a formal [3+2] cycloaddition based on synergistic catalysis. Vinylcyclopropanes derived from cyanoesters react with enals by dual activation using palladium(0) and secondary amines to form the corresponding cyclopentanes
Bromine Radical Catalysis by Energy Transfer Photosensitization
作者:Dian-Feng Chen、Cameron H. Chrisman、Garret M. Miyake
DOI:10.1021/acscatal.0c00281
日期:2020.2.21
user-friendly bromine radical catalysis system that enables efficient [3 + 2] cycloaddition of diversely substituted vinyl- and ethynylcyclopropanes with a broad range of alkenes, including drug-like molecules and pharmaceuticals. Key to the success is the use of photosensitizing triplet-state β-fragmentation of a judiciously selected precatalyst, cinnamyl bromide, to generate bromine radicals in a
conjugate addition of 1-alkenyl(disiamyl)boranes to α,β-unsaturated ketones, esters, or nitriles was carried out in the presence of Ni(acac)2 and triethylamine in DMF. The reactions provided γ,δ-unsaturated ketones, esters, and nitriles in high yields while retaining the original configuration of the 1-alkenylboranes. A similar addition reaction of 1-alkenyl(disiamyl)boranes to 1-acetyl-2-vinylcyclopropane
C3-Allylation of Indoles via an Iridium-Catalyzed Branch-Selective Ring-Opening Reaction of Vinylcyclopropanes
作者:Guang-Jian Mei、Feng Shi、Lei Yu、Zi-Qi Zhu、Meng Sun
DOI:10.1055/s-0037-1611355
日期:2019.4
chemistry of vinylcyclopropanes. An iridium-catalyzed branch-selective ring-openingreaction of vinylcyclopropanes with indoles has been established, which afforded C3-allylindoles in generally good to excellent yields (up to 95%). Considering that no wastes were generated in the whole process and branch-selective ring-openingreaction of vinylcyclopropanes was rarely reported, this strategy not only can