Build-up of double carbohelicenes using nitroarenes: dual role of the nitro functionality as an activating and leaving group
作者:Fulin Zhou、Fujian Zhou、Rongchuan Su、Yudong Yang、Jingsong You
DOI:10.1039/d0sc02058c
日期:——
streamlined and simplified synthetic route to double carbohelicenes starting from nitroarenes through sequential nitro-activated ortho-C–H arylation, denitrative alkenylation and intramolecular cyclodehydrogenation. In this synthetic strategy, the nitro group plays a dual role namely as a leaving group for the denitrative alkenylation and as an activating group for ortho-C–H arylation, which is distinct
Stereodivergent Alkyne Reduction by using Water as the Hydrogen Source
作者:Santhosh Rao、Kandikere Ramaiah Prabhu
DOI:10.1002/chem.201803147
日期:2018.9.18
homogeneous Pd‐catalyzed stereodivergent reduction of alkynes to Z and E alkenes by using H2O as the H2 source is presented. Mediated by a diboron reagent, the transfer hydrogenation has been accomplished to yield the desired geometrical isomer by rational ligand selection. The switchable stereoselectivity achieved using simple phosphine ligands is generally excellent. D2O has also been used as a D2 source
nucleophilic addn. of an organolithium reagent to DMF are basic enough to deprotonate alkyltriphenylphosphonium salts suspended in THF. The aldehydes, liberated by the spontaneous decompn. of the resulting a-amino alcs. (hemi-aminals), undergo a Wittig reaction with the simultaneously generated P ylides to afford olefins in excellent overall yields. This in situ method offers the unique advantage in
Li a-(二甲氨基)醇盐由亲核加成物产生。有机锂试剂对 DMF 的碱性足以使悬浮在 THF 中的烷基三苯基鏻盐去质子化。醛,由自发分解释放。产生的α-氨基醇。(半缩醛胺),与同时生成的 P 叶立德进行 Wittig 反应,以优异的总产率提供烯烃。这种原位方法在其适用于不稳定醛方面提供了独特的优势,否则这些醛将成为 (Z/E)-异构化或自缩合过程的牺牲品。[在 SciFinder (R) 上]
One-Pot Synthesis of Stilbenes
from Alcohols through a Wittig-Type Olefination Reaction
Promoted by Nickel Nanoparticles
作者:Francisco Alonso、Miguel Yus、Paola Riente
DOI:10.1055/s-0029-1217333
日期:——
A series of stilbenes has been synthesised in one pot from benzyl alcohols and benzylidenetriphenylphosphorane through a Wittig-typeolefination reaction in the presence of nickelnanoparticles.
μ-Chlorido, μ-hydroxo-bridged ruthenacycles containing the Ru(CO)2 motif were synthesized by reaction of μ-dichlorido-bridged congener complexes with water in the presence of disodium carbonate. The substitution of one chlorido ligand for one hydroxo occurs with high stereoselectivity affording essentially hydroxo-bridged ruthenacycles, whereby the OH ligand occupies axial positions with respect to the mean plane defined by the chelating ligand. According to computational DFT investigations this stereoselectivity stems from a marked transphobia of the hydroxo ligand towards the carbanion of the ruthenacycle. The catalytic properties of the title compounds in hydrogen atom transfer process and particularly in the partial hydrogenation of alkynes have been investigated.