1-Phenylthio-3-vinyl-3-cyclohexenol, a new reagent for bis-annelation of silyl enol ethers
作者:Olga Konstantinova、Florence C.E. Sarabèr、Enrique Melguizo、Ben J.M. Jansen、Aede de Groot
DOI:10.1016/j.tet.2005.11.060
日期:2006.2
1-Phenylthio-3-vinyl-cyclohex-1-en-3-ol (2) has been synthesized and investigated as a new bis-annelation reagent for silyl enol ethers. Reagent 2 can be synthesized by a Grignard reaction of vinyl magnesium bromide with 3-phenylthiocyclohexenone. The reaction with silyl enol ethers takes place under Lewis acid catalysis and generally proceeds in good yields. The resulting phenylthiodienes can be hydrolyzed
Nucleophilic reactions of various enol silylethers with carbocation species generated from propargylsilylethers by the action of a Lewis acid have been developed. The present method is highly useful for the introduction of allenic or enyne functionalities into the alpha-position of substituted ketones. [reaction--see text]
A new catalytic asymmetric tandem α‐alkenyl addition/proton shift reaction of silyl enol ethers with ketimines was serendipitously discovered in the presence of chiral N,N′‐dioxide/ZnII complexes. The proton shift preferentially proceeded instead of a silyl shift after α‐alkenyl addition of silyl enol ether to the ketimine. A wide range of β‐amino silyl enol ethers were synthesized in high yields with
Computationally Guided Stereocontrol of the Combined CH Functionalization/Cope Rearrangement
作者:Yajing Lian、Kenneth I. Hardcastle、Huw M. L. Davies
DOI:10.1002/anie.201103568
日期:2011.9.26
Diastereoselectivity in control: The synthetic utility of the CH functionalization/Coperearrangementreaction has been greatly expanded by the design of substrates that will react through a boattransition state instead of a chairtransition state. The products are formed with the opposite diastereoselectivity as previously obtained (see scheme, ABSA= acetamidobenzenesulfonylazide).
Alkynoate Synthesis through the Vinylogous Reactivity of Rhodium(II) Carbenoids
作者:Damien Valette、Yajing Lian、John P. Haydek、Kenneth I. Hardcastle、Huw M. L. Davies
DOI:10.1002/anie.201204047
日期:2012.8.20
Siloxy group migration: A rhodium(II) carbenoid approach has been developed for the synthesis of alkynoates (see scheme). This transformation combines the addition of enol ethers at the vinylogous position of β‐siloxy‐substituted vinyldiazo derivatives with a siloxy group migration to give the products as single diastereomers.