Rhodium(II)-Catalyzed Reaction of 1-Tosyl-1,2,3-triazoles with Morita-Baylis-Hillman Adducts: Synthesis of 3,4-Fused Pyrroles
作者:Renmeng Jia、Jiang Meng、Jiaying Leng、Xingxin Yu、Wei-Ping Deng
DOI:10.1002/asia.201800057
日期:2018.9.4
A cascade reaction of rhodium azavinylcarbenes with Morita–Baylis–Hillman (MBH) adducts enables a novel synthetic approach to 3,4‐fused pyrroles. The cascade reaction begins with the insertion of O−H bond into rhodium azavinylcarbenes, subsquent sigmatropic rearrangement provides substituted α,β‐unsaturated cyclic ketone intermediates. Then the intramolecular aza Michael addition/oxidative aromatization
from 2-cyclohexanones and diverse aldehydes under palladium catalysis, by in situ generation of electron-neutral and HOMO-raised η2-Pd(0)-dienone complexes via an oxidative insertion/π–σ-isomerization/β-H elimination activation sequence. The subsequent umpolung vinylogousaddition to a variety of imines is realized upon Pd(0)-mediated π-Lewis base catalysis, finally furnishing o-cresolylated products
在这里,我们报告了在钯催化下与 Morita- Baylis -Hillman (MBH) 碳酸酯在钯催化下的不对称形式亲核亲核化反应,通过原位产生电子中性和 HOMO 引发的 η 2 -Pd( 0)-二烯酮复合物通过氧化插入/π-σ-异构化/β-H消除激活序列。随后在 Pd(0) 介导的 π-Lewis 碱催化下实现了对各种亚胺的 umpolung 插烯加成,最终提供了o-甲酚化产物,然后是另一个级联的 π-σ-异构化/β-H 消除/芳构化过程。通过采用新设计的庞大的手性亚膦酰胺配体,对大量的底物组装实现了中等至优异的非对映和对映选择性,并且可以轻松地加工所得的多功能产品以获取多种对映体富集的结构。此外,催化反应途径通过对照实验得到了很好的启发。
NaNO<sub>2</sub>-catalyzed reaction of cyclohexenone-MBH acetates: A convenient synthesis of 2-methylene-3-cyclohexenones
Abstract An efficient NaNO2-catalyzed synthesis of 2-methylene-3-cyclohexenones from easily accessible cyclohexenone-MBH acetates has been established for the first time. Target products were rapidly generated in moderate to high yields and with relatively high E/Z selectivity. Easy operation, good functional group tolerance, mild reaction conditions and the practicality of high efficiency of NaNO2
Regioselective Synthesis and Structural Studies of Substituted γ-Hydroxybutenolides with Use of a Tandem Baylis−Hillman/Singlet Oxygenation Reaction
作者:Santoshkumar N. Patil、Fei Liu
DOI:10.1021/jo702762u
日期:2008.6.1
scope and limitations of a regioselective synthesis of either α- or β-substituted γ-hydroxybutenolides from 3-furfural and enones are described. The sequence features a Baylis−Hillman reaction followed by singlet oxygen oxidation with use of either an amine base or TBAF as the regioselectivity switches. Structural studies in solution on some of the resulting γ-hydroxybutenolides are also reported.