Two new “one pot” double alkylation reactions, 1) allylation of α,β-enones with allylsilanes and subsequent reaction with electrophiles, and 2) acylation of α-siloxyallylsilanes with acid halides followed by consecutive introduction of other electrophiles on the neighboring carbon atom, are reported.
Asymmetric Induction in [3 + 2] Dipolar Cycloaddition Reactions of Nitrile Oxides with Chiral (α-Oxyallyl)silanes
作者:Dennis P. Curran、Scott A. Gothe
DOI:10.1016/s0040-4020(01)86647-3
日期:1988.1
The dipolar cycloaddition reactions of(α-oxyallyl)silanes 12a-g with 2,2-dimethylpropanenitrile oxide and benzonitrile oxide have been studied. Mixtures of anti (14a-g and 16a-g) and syn (15a-g and 17a-g) Δ2-isoxazolines are formed. The direction and magnitude of asymmetricinduction depends on the allylie oxygen substituent: a free hydroxy provides a modest excess of the syn diastereomer, a silyl
Regioselection in the reaction of α-silyloxyallyl carbanions with electrrophiles
作者:P.W.K. Lau、T.H. Chan
DOI:10.1016/s0022-328x(00)95228-8
日期:1979.10
Regioselection in the reaction of α-silyloxyallyl carbanion with electrophiles has been found to change with the nature of leaving groups in the electrophiles.
Stereoconvergent [1,2]- and [1,4]-Wittig Rearrangements of 2-Silyl-6-aryl-5,6-dihydropyrans: A Tale of Steric vs Electronic Regiocontrol of Divergent Pathways
作者:Luis M. Mori-Quiroz、Robert E. Maleczka
DOI:10.1021/jo5026942
日期:2015.1.16
The regiodivergent ring contraction of diastereomeric 2-silyl-5,6-dihydro-6-aryl-(2H)-pyrans via [1,2]- and [1,4]-Wittig rearrangements to the corresponding a-silylcyclopentenols or (alpha-cyclopropyl)acylsilanes favor the [1,4]-pathway by ortho and para directing groups in the aromatic appendage and/or by sterically demanding silyl groups. The [1,2]-pathway is dominant with meta directing or electron-poor aromatic moieties. Exclusive [1,2]-Wittig rearrangements are observed when olefin substituents proximal to the silyl are present. cis and trans diastereomers exhibit different reactivities, but converge to a single [1,2]- or [1,4]-Wittig product with high diastereoselectivity and yield.
Chemistry of organosilicon compounds. 106. .alpha.-Siloxyallylsilanes as homoenolate anion equivalents. A novel synthesis of .gamma.-keto aldehydes