new approach has been demonstrated for the regiospecific aldol synthesis by the simultaneous addition of α-halo carbonyl derivatives and aldehydes or ketones to a suspension of diethylaluminum chloride and zinc in tetrahydrofuran at low temperature. This technique is also employable under mild conditions for the Reformatsky reaction to give β-hiydroxy esters in excellent yield. One of the unique synthetic
New Application of Solid Acid to Carbon–Carbon Bond Formation Reactions: Clay Montmorillonite-Catalyzed Aldol Reactions of Silyl Enol Ethers with Aldehydes and Acetals
作者:Motomitsu Kawai、Makoto Onaka、Yusuke Izumi
DOI:10.1246/bcsj.61.1237
日期:1988.4
A new attempt of utilizing solid acid to the cross aldol reaction of silylenolethers with aldehydes or acetals has been investigated. Among solid acids employed, the reaction is promoted most effectively by a catalytic amount of aluminium ion-exchanged montmorillonite (Al-Mont). Simple diastereoselection is significantly sensitive to the nature of the reaction solvent used in the Al-Mont-catalyzed
Mukaiyama Aldol Reactions of Silyl Enolates Catalyzed by Iodine
作者:Prodeep Phukan
DOI:10.1081/scc-120028638
日期:2004.12.31
Abstract Iodine catalyzedMukaiyamaaldolreaction of silyl enol ethers and silyl ketene acetal with aldehydes, ketones and acetals in good yield with preferential antiselectivity has been described.
Trimethylsilyl trifltate catalyzed aldol-type reaction of enol silyl ethers and acetals or related compounds
作者:Shizuaki Murata、Masaaki Suzuki、Ryoji Noyori
DOI:10.1016/s0040-4020(01)86671-0
日期:1988.1
condensation of enol trimethylsllyl ethers with acetals, orthoformate, or 2-acetoxytetrahydrofuran or -pyrans to give the corresponding β-alkoxy carbonylcompounds. Reaction of enolsilylethers and carboxonium triflate ion-pair intermediates occurs via acyclic transition states and exhibits moderate to high erythro selectivity independent of the geometry (E/Z) of the enolsilylethers.
Polymer-bound lithiumamides were used in an aldol reaction. The introduction of a spacer between the polymer backbone and the reactive site was important to enhance yields of the aldol products. The polymer-bound reagent was repeatedly used in the same reaction after the conversion to the lithium amide.