Multicatalytic Stereoselective Synthesis of Highly Substituted Alkenes by Sequential Isomerization/Cross-Coupling Reactions
作者:Ciro Romano、Clément Mazet
DOI:10.1021/jacs.8b02134
日期:2018.4.4
patterns to deliver products with high control of the newly generated C═C bond. A highlyenantioselective variant of this [Ir/Ni] sequence has been established using a chiral iridium precatalyst. A complementary [Pd/Ni] catalytic sequence has been optimized for alkenyl methyl ethers with a remote C═C bond. The final alkenes were isolated with a lower level of stereocontrol. Upon proper choice of the Grignard
Palladium-catalysed cross-coupling of a new umpolung reagent, (α-methoxy-γ-tributylstannyl)allyltrimethyl-silane, with acyl or aryl halides, involves exclusively the vinyl–tin bond and subsequent desilylation with tetrabutylammonium fluoride gives enol ethers, precursors of β-acyl- or β-aryl-propionaldehydes.
Three different routes for the stereoselectivesynthesis of botryodiplodin have been investigated. The intramolecular allylation of acetals proved to be unsatisfactory due to unstable intermediates and poor stereocontrol. Zard intramolecular radical allylation of a 2-iodopropionate derivative allows the development of an expeditious synthesis of racemic botryodiplodin. The relative configuration within
A new one pot protocol has been developed for the reductive silylation of alkenyl methyl ethers using Et3Si–BPin and HSiEt3 with nickel(II) catalyst. Styrene type methyl ethers, multi-substituted vinyl methyl ethers, heterocycles and unconjugated vinyl ethers are all tolerated to form alkyl silanes. Mechanistic study reveals that it is a cascade of a C–O bond silylation and vinyl double bond hydrogenation
Probing Intramolecular Electron Transfer in Redox Tag Processes
作者:Naoya Maeta、Hidehiro Kamiya、Yohei Okada
DOI:10.1021/acs.orglett.9b02808
日期:2019.11.1
cycloaddition can be used as a probe to investigate intramolecular single-electron transfer (SET) mechanisms. The efficacy of intramolecular SET can be evaluated in association with concomitant carbon–carbon bond formation and/or cleavage, leading to cycloaddition or cross-metathesis. Experimental and theoretical results suggest that the intramolecular SET is under both thermodynamic and kinetic control