Diastereoselective Allylation and Crotylation Reactions of Aldehydes with Potassium Allyl- and Crotyltrifluoroborates under Lewis Acid Catalysis
作者:Robert A. Batey、Avinash N. Thadani、David V. Smil、Alan J. Lough
DOI:10.1055/s-2000-6303
日期:——
Potassium allyl- and crotyltrifluoroborates react with aldehydes in a process catalyzed by a variety of Lewis acids, to give the corresponding homoallylic alcohols. Of the Lewis acids examined, BF3 · OEt2, used either stoichiometrically or catalytically, was found to most efficiently catalyze this reaction. The air and moisture stable potassium organotrifluoroborate salts react with a variety of alkyl, α- or β-substituted alkyl, and aryl aldehydes, and lead to the adducts in high yield and with high diastereoselectivity.
Potassium allyl- and crotyltrifluoroborates: Stable and efficient agents for allylation and crotylation
作者:Robert A. Batey、Avinash N. Thadani、David V. Smil
DOI:10.1016/s0040-4039(99)00774-1
日期:1999.6
Potassium allyl- and crotyltrifluoroborates react rapidly with aldehydes in the presence of BF3·Et2O. These salts are stable to air and moisture, and lead to adducts in high yield and with high diastereoselectivity. The stereochemistry of the crotylated products is consistent with the reaction via allylboron difluoride and a Zimmerman-Traxler like transition state.
Nozaki−Hiyama−Kishi Reactions Catalytic in Chromium
作者:Alois Fürstner、Nongyuan Shi
DOI:10.1021/ja9625236
日期:1996.1.1
chromium-catalyzed additions of organic halides to aldehydes (“Nozaki−Hiyama−Kishi reactions”). The reactions are mediated by trimethylchlorosilane, and the active Cr2+ species is constantly recycled by means of nontoxic, commercial manganese powder as the stoichiometric reductant. This method nicely applies to different substituted aryl, heteroaryl, alkynyl, alkenyl, and allylhalides as well as to alkenyl triflates
Crotylation of Aldehydes by Crotyltins: Discrimination between Mechanisms Involving Transmetallation or Simple Lewis Acid Assistance through the Consideration of the Stereochemistry of the Corresponding Homoallylic Alcohols
In the reaction of crotyltins with aldehydes in the presence of metal salts, the double consideration of the syn/anti ratio of the branched homoallylicalcohols and the Z/E ratio of their linear regioisomers is proposed as a way to discriminate between a reaction mechanism involving a transmetallation step and a reaction mechanism involving simple Lewis acid activation of the aldehyde. The formation
Intervention of the boat transition state in the allylic tin–aldehyde condensation at high pressure
作者:Yoshinori Yamamoto、Ken-ichi Saito
DOI:10.1039/c39890001676
日期:——
The volume data of the octanal–crotyltin condensation are obtained from the pressure dependence of the rate coefficient and of diastereoselectivity; analysis of ΔV‡, ΔΔV‡, and V‡ indicates the intervention of the boattransitionstate under highpressurecondensation.
从速率系数和非对映选择性的压力依赖性中获得了辛格-crotyltin缩合的体积数据。Δ的分析V ‡,ΔΔ V ‡,和V ‡表示船过渡态的高压下凝结的干预。