Effective 1,5-Asymmetric Induction in Tin(IV) Chloride Promoted Reactions Between Aldehydes and (4-Alkoxy-2-alkenyl)tributylstannanes
作者:Alan H. Mcneill、Eric J. Thomas
DOI:10.1055/s-1994-25469
日期:——
Transmetallation of (S)-4-benzyloxy-2-pentenyl(tributyl)stannane (1) using tin(IV) chloride generates an allyltin trichloride which reacts in situ with aldehydes to give 1-substituted syn-(3Z)-5-benzyloxyhexenols with excellent stereoselectivity. With chiral aldehydes, the stereoselectivity of the reaction is dominated by the reagent, except for 2-alkoxyaldehydes which show matching and mismatching consistent with preferred Felkin-Anh diastereofacial selectivity.
Palladium-catalysed hydrostannylations of 1-bromoalkynes. A practical synthesis of (E)-1-stannylalk-1-enes
作者:Christopher D. J. Boden、Gerald Pattenden、Tao Ye
DOI:10.1039/p19960002417
日期:——
A practical synthesis of (E)-1-stannylalk-1-enes containing a range of oxygen and nitrogen functionality is highlighted, involving hydrostannylation followed by palladium-catalysed carbon–bromine bond cleavage reactions of 1-bromoalkynes.
Formal Regiocontrolled Hydroboration of Unbiased Internal Alkynes via Borylation/Allylic Alkylation of Terminal Alkynes
作者:Abraham L. Moure、Pablo Mauleón、Ramón Gómez Arrayás、Juan Carlos Carretero
DOI:10.1021/ol4007663
日期:2013.4.19
boronates from terminalalkynes, a propargyl directing (2-pyridyl)sulfonyl group allows terminalalkynes to undergo Cu-catalyzed B2(pin)2-borylation and subsequent Cu-catalyzed allylic alkylation with Grignard reagents without affecting the pinacolboronate moiety, thereby formally enabling a highly stereo- and regiocontrolled access to hydroboration products of unbiased dialkyl internal alkynes.
Stereoselective Synthesis of Tetrasubstituted Olefins through a Halogen-Induced 1,2-Silyl Migration
作者:Nicholas T. Barczak、Douglas A. Rooke、Zachary A. Menard、Eric M. Ferreira
DOI:10.1002/anie.201303007
日期:2013.7.15
Migrating through Si valley: The highly stereoselective formation of α‐silyl‐β‐ haloenones by way of silicon group migration is described. Electrophilic activation of the alkyne by N‐halosuccinimides induced an anti‐selectivemigration to give highly substituted enones (see scheme). These enone products can be readily converted to the all‐carbon tetrasubstituted alkenes while maintaining their geometry
Rhenium(I)-Catalyzed Generation of α,β-Unsaturated Carbene Complex Intermediates from Propargyl Ethers for the Preparation of Cycloheptadiene Derivatives
作者:Hideyuki Sogo、Nobuharu Iwasawa
DOI:10.1002/anie.201604371
日期:2016.8.16
The rhenium(I)‐catalyzed generation of α,β‐unsaturated carbene complex intermediates from easily available propargyl ethers was achieved for the concise construction of cycloheptadiene derivativesthrough the formal [4+3] cycloaddition reaction with siloxydienes.