Allylation of Aldehydes Promoted by the Cerium(III) Chloride Heptahydrate/Sodium Iodide System: the Dependence of Regio- and Stereocontrol on the Reaction Conditions
The cerium(III) chloride heptahydrate/sodium iodide complex (CeCl3 ⋅ 7 H2O/NaI) acts as a useful promoter in the carbon-carbonbond forming reaction by addition of allyltributylstannanes to aldehydes. The reaction of 2-butenyltributylstannane shows that the regio- and the stereochemical outcomes depend on the reaction conditions. When the promoter is adsorbed on a solid support (aluminum oxide), a
铈(III)七水合氯化/碘化钠复合物(加入CeCl 3 ⋅7 H 2 O / NAI)作为在碳-碳键形成通过加入allyltributylstannanes醛的反应的有用的启动子。2-丁烯基三丁基锡烷的反应表明区域和立体化学结果取决于反应条件。当促进剂吸附在固体载体(氧化铝)上时,在无溶剂条件下会观察到非常普遍的γ加合物形成。相反,当反应在乙腈作为溶剂中进行时,α-加合物占优势。在最后一种情况下,观察到完全的立体控制,以高几何纯度获得较不稳定的(Z)-异构体。
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.
An efficient method for the allylation of aldehydes containing a broad range of functional groups using potassium allyltrifluoroborate is described. The reaction utilizes a catalytic amount of 18-C-6 in biphasic media under open atmosphere and room temperature to provide the corresponding homoallylic alcohols in high yields and without the necessity of any subsequent purification.
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.
Palladium-Catalyzed Coupling of Allyl Acetates with Aldehyde and Imine Electrophiles in the Presence of Bis(pinacolato)diboron
作者:Sara Sebelius、Olov A. Wallner、Kálmán J. Szabó
DOI:10.1021/ol035052i
日期:2003.8.1
(4) electrophiles to afford homoallylicalcohols (5a-h) and amines (6a-d), respectively. A particularly interesting mechanistic feature is that the allylic substitution of the transient allyl boronate with sulfon-imine requires palladium catalysis. This finding indicates that the formation of the homoallylic amine derivatives (6a-d) involves bis-allylpalladium intermediates.