efficient rhodium-catalyzed β-dehydroborylation of aldehyde-derived silyl enol ethers (SEEs) with bis(pinacolato)diboron (B2pin2) is disclosed. The borylation reactions proceeded well with alkyl- and aryl-substituted SEEs, affording a wide array of valuable functionalized β-boryl silyl enolates with high efficiency and excellent stereoselectivity. Moreover, the borylated products, through versatile
公开了醛衍生的甲硅烷基烯醇醚(SEE)与双(频哪醇)二硼(B 2 pin 2 )的有效铑催化的β-脱硼氢化。硼基化反应与烷基和芳基取代的 SEE 进行得很好,提供了一系列有价值的功能化 β-硼基甲硅烷基烯醇化物,具有高效率和优异的立体选择性。此外,borylated产品,通过通用的碳-硼键的变换,被容易地转化为合成多样有用分子,包括α羟基酮,官能看到,和宝石-difunctionalized醛。
AuCl3/AgSbF6-catalyzed rapid epoxide to carbonyl rearrangement
作者:Vanajakshi Gudla、Rengarajan Balamurugan
DOI:10.1016/j.tetlet.2012.07.056
日期:2012.9
An efficient epoxide to carbonyl rearrangement using catalytic AuCl3/AgSbF6 has been presented. The reactions are fast and high yielding. β-Hydrogen migration takes place exclusively when hydrogen and methyl or substituted methyl groups are present at β-carbon of epoxide. When phenyl/acetyl/benzoyl and hydrogen are available at same carbon atom, migration of the former is preferred over the latter
Metalloporphyrin as an Efficient Catalyst in the Regioselective Isomerization of Epoxides to Carbonyl Compounds
作者:Toshikatsu Takanami、Rina Hirabe、Masayoshi Ueno、Fumio Hino、Kohji Suda
DOI:10.1246/cl.1996.1031
日期:1996.12
Regioselective ring-opening isomerization of epoxides to carbonylcompounds can effectively be catalyzed by iron (III) tetraphenylporphyrin, Fe(tpp)ClO4.
characteristic Lewis acid catalyst in the regio- and stereoselective rearrangement of epoxides to aldehydes. This Cr(TPP)OTf-catalyzed reaction is an operationally simple and especially convenient method for synthesizing optically active beta-siloxy aldehydes from 2,3-epoxy silyl ethers which are readily available in enantiomerically enriched forms by the Sharpless epoxidation of allylic alcohols followed
Chemocontrolled reduction of α-keto esters by hydrides: a possible solution for selective reduction of the ester function
作者:V. Dalla、J.P. Catteau
DOI:10.1016/s0040-4020(99)00317-8
日期:1999.5
ketones have been obtained with a high level of selectivity from enolic α-keto esters in two steps, with the reduction of the α-silyloxy α,β-unsaturated ester by LiAlH4 as the key step. The methodology developed in this work represents a “reversed” chemoselective reduction of the ester group instead of the keto of an enolic α-keto ester due to a one-pot sequential ester reduction-desilylation or silyl migration