Synthesis of α,β-Unsaturated Aldehydes and Methyl Carboxylic Esters from 2-Acetylenic Phenyl Sulfides.
摘要:
2-Alkynylthio benzenes were reduced to 2-Alkenylthio benzenes with diisobutyl aluminum hydride. Mono chlorination of these compounds with sulfuryl chloride and pyridine followed by hydrolysis, in the presence of Cu-II salts, gave alpha,beta-unsaturated aldehydes.2-Alkynylthio benzenes were converted into 2-Alkynyl 1,1-bis thiobenzenes by monochlorination with sulfuryl chloride and pyridine followed by treatment with thiophenol and triethylamine. These substances were then converted to alpha,beta-unsaturated methyl carboxylic esters by way of isomerization with sodium methoxide to the corresponding allene and treatment with hydrochloric acid and methanolysis in the presence of iodine.
4-addition and [3 + 2] cycloaddition reactions using chiral calcium species prepared from calcium isopropoxide and chiral bisoxazoline ligands have been developed. Glycine Schiff bases reacted with acrylic esters to afford 1,4-addition products, glutamic acid derivatives, in high yields with high enantioselectivities. During the investigation of the 1,4-addition reactions, we unexpectedly found that a [3
Water is demonstrated to be an excellent medium for the Wittigreaction employing stabilized ylides and aldehydes. Although the solubility in water appears to be an unimportant characteristic in achieving good chemical yields and E/Z-ratios, the rate of Wittigreactions in water is unexpectedly accelerated.
Well-Defined and Robust Rhodium Catalysts for the Hydroacylation of Terminal and Internal Alkenes
作者:Amparo Prades、Maitane Fernández、Sebastian D. Pike、Michael C. Willis、Andrew S. Weller
DOI:10.1002/anie.201503208
日期:2015.7.13
A Rh‐catalyst system based on the asymmetric ligand tBu2PCH2P(o‐C6H4OMe)2 is reported that allows for the hydroacylation of challenging internalalkenes with β‐substituted aldehydes. Mechanistic studies point to the stabilizing role of both excess alkene and the OMe‐group.
据报道,基于不对称配体t Bu 2 PCH 2 P( o -C 6 H 4 OMe) 2的 Rh 催化剂系统可以用 β 取代醛对具有挑战性的内烯烃进行加氢酰化。机理研究指出了过量烯烃和 OMe 基团的稳定作用。