An unprecedented Lewis acidcatalyzed, protection-free, and high-efficiency synthesis of valuable 3,4-dihydro-2H-2,4-methanochromans via cycloaddition of propargylic alkynols with 2-vinylphenol is described. This cycloaddition protocol, which tolerates a wide variety of functional groups, provides practical, versatile, and atom-economical access to a new class of appealing bridged-ring products in
本文描述了一种空前的路易斯酸,其通过炔丙基炔醇与2-乙烯基苯酚的环加成反应,催化了有价值的3,4-二氢-2 H -2,4-甲烷二甲基苯并没有保护性地进行了高效合成。该环加成方案可耐受多种官能团,以令人满意的收率提供实用,通用且经济实惠的途径来获得新型的有吸引力的桥环产品。与报道的桥环骨架合成反应条件相比,目前的反应条件是中性,温和且没有任何添加剂。
Aryloxybenzylidene Ruthenium Chelates: Synthesis, Structure and Catalytic Activity in Olefin Metathesis
behave like a promising latent catalyst of olefinmetathesis. The catalysts are characterised by substantial stability and catalytic inactivity in their dormant forms and a dramatic increase in activity after addition of a solution of HCl in ether. The mechanism of activation involves protonation of the phenoxide and the formation of a highly catalytically active hydroxybenzylidene ruthenium chelate
作者:Marvin Parasram、Viktor O. Iaroshenko、Vladimir Gevorgyan
DOI:10.1021/ja5104525
日期:2014.12.31
A palladium (Pd)-catalyzed endo-selectiveHeckreaction of iodomethylsilyl ethers of phenols and aliphatic alkenols has been developed. Mechanistic studies reveal that this silyl methyl Heckreaction operates via a hybrid Pd-radical process and that the silicon atom is crucial for the observed endo selectivity. The obtained allylic silyloxycycles were further oxidized into (Z)-alkenyldiols.
new cobalt-catalyzed phenolic OH-assisted C–H functionalization of 2-vinylphenols with allenes to give various 2H-chromenes is described. It is the first time that allenes are used as the coupling partners in the cobalt-catalyzed C–H activation reactions. In most cases, cobalt-catalyzed oxidative annulation of arenes with alkenes or alkynes via C–H activation gave [4 + 2] or [3 + 2] cyclization products