Highly Efficient Activation of Organosilanes with η2-Aldehyde Nickel Complexes: Key for Catalytic Syntheses of Aryl-, Vinyl-, and Alkynyl-Benzoxasiloles
摘要:
An eta(2)-aldehyde nickel complex was utilized as an effective activator for an organosilane in order to generate a hypervalent silicate reactant for the first time. This method was successfully applied to the highly efficient syntheses of 3-aryl-, vinyl-, and alkynyl-2,1-benzoxasiloles from benzaldehydes with aryl-, vinyl-, and alkynylsilyl groups at the ortho position. Initial mechanistic studies revealed that an intermolecular aryl transfer process was involved in the reaction mechanism. The formation of an eta(2)-aldehyde complex was directly confirmed by NMR.
Copper-Catalyzed Dehydrative Cyclization of 1-(2-Hydroxyphenyl)propargyl Alcohols with P(O)H Compounds for the Synthesis of 2-Phosphorylmethylbenzofurans
A tetrakis(acetonitrile)copper(I) hexafluorophosphate [Cu(MeCN)PF6]‐catalyzed dehydrative reaction of 1‐(2‐hydroxyphenyl)propargyl alcohols with diarylphosphine oxides has been developed to provide an efficient synthesis of phosphorylated benzofurans in good to high yields. In the presence of a catalytic amount of an organic base, a variety of H‐phosphonates and H‐phosphinates can also be employed
propargylation of CoQ0 is described by employing the cooperative effect of Sc(OTf)3 and Hantzschester. It is suggested to work through the redox chain reaction, which involves hydroquinone and dimeric propargylic moiety intermediates. A broad range of propargylic alcohols can be converted into the appropriate derivatives of CoQ0 containing triple bonds in good to excellent yields. The mechanism of the given
Copper(I)-Catalyzed Hydroalkoxylation/Hydrogen-Bonding-Induced Asymmetric Hetero-Diels-Alder Cycloaddition Cascade: An Approach to Aromatic Spiroketals
作者:Xin Li、Jijun Xue、Chusheng Huang、Ying Li
DOI:10.1002/asia.201101056
日期:2012.5
One thing leads to another: Bis(benzannelated) 5,6‐spiroketal skeletons can be constructed by an efficient cascade process involving an unprecedented CuI‐catalyzed intramolecular alkyne hydroalkoxylation and an asymmetric hetero‐Diels–Alder cycloaddition. The method yields a series of diversely functionalized spiroketals from two readily available open‐chained starting materials in good yields and
Simultaneous Generation and Subsequent Cycloaddition of <i>ortho</i>
-Quinonemethides and Cyclic Enecarbamates Promoted by a Gold/Lewis Acid Catalytic System
作者:Patricia Fernández、Pedro Alonso、Francisco J. Fañanás、Félix Rodríguez
DOI:10.1002/ejoc.201800679
日期:2018.8.7
A gold/BF3 catalytic system promotes the transformation of simple 3‐butynamines and 2‐(hydroxymethyl)phenol derivatives into cyclic enamines and ortho‐quinone methide derivatives. The subsequent formal [4+2]‐cyclization reaction between these two intermediates gives rise to hexahydrochromeno[2,3‐b]pyrrole derivatives.
金/ BF 3催化体系促进简单的3-丁炔胺和2-(羟甲基)苯酚衍生物转化为环烯胺和邻醌甲基化物衍生物。这两个中间体之间随后的正式的[4 + 2]-环化反应产生了六氢色素[2,3- b ]吡咯衍生物。
Catalytic Asymmetric Cycloaddition of In Situ-Generated <i>ortho</i>
-Quinone Methides and Azlactones by a Triple Brønsted Acid Activation Strategy
A convergent and highly stereoselective [4+2] cycloaddition of in situ‐generated ortho‐Quinone methides (o‐QMs) and azlactone enols has been successfully developed through a triple Brønsted acid catalysis strategy. This protocol provides an efficient and mild access to various densely functionalized dihydrocoumarins bearing adjacent quaternary and tertiary stereogenic centers in high yields with excellent