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。
Synthesis of 1-acetyl-2-silyoxycycloheptane derivatives via highly stereoselective formal [5+2] cycloaddition reaction
A stereoselective [5+2] cycloaddition reaction using a new five-carbonunit, that has a dicobalt acetylene complex moiety and an enol silyl ether moiety, was developed. In the presence of a Lewis acid, the five-carbonunit reacted with an enol triisopropylsilyl ether to give a 1-acetyl-2-silyoxycycloheptane derivative, in which the three contiguous substituents on the seven-membered ring arrange cis
chiral boron compounds. This protocol is well suitable for activated alkenes such as vinylarenes and alkenes bearing directing groups. However, the catalytic enantioselective hydroboration of O-substituted alkenes has remained unprecedented. Here we report a Rh-catalyzedenantioselective hydroboration of silyl enol ethers (SEEs) that utilizes two new chiral phosphine ligands we developed. This approach