Scope and Mechanism of the Ruthenium-Catalyzed Dehydrative C–H Coupling of Phenols with α,β-Unsaturated Carbonyl Compounds: Expedient Synthesis of Chromene and Benzoxacyclic Derivatives
作者:Bhanudas Dattatray Mokar、Chae S. Yi
DOI:10.1021/acs.organomet.9b00629
日期:2019.12.23
4-disubstituted chromene derivatives, whereas the analogous coupling with cyclic enones yielded 9-hydroxybenzoxazole products. The reaction of 3,5-dimethoxyphenol with PhCH═CHCDO resulted in the chromene product with a significant H/Dexchange to both benzylic and vinyl positions. The most significant carbon isotope effect from the coupling of 3,5-dimethoxyphenol with 4-methoxycinnamaldehyde was observed
ne烯和苯并氧杂环衍生物是通过苯酚与α,β-不饱和羰基化合物的钌催化脱水CH-H偶联反应有效合成的。发现阳离子钌氢化物络合物是有效的催化剂,可用于苯酚与烯类的偶联和环化,形成苯并二氢萘产品。苯酚与线性烯酮的偶合得到2,4-二取代的色烯衍生物,而与环烯酮的类似偶合产生9-羟基苯并恶唑产物。3,5-二甲氧基苯酚与PhCH = CHCDO的反应生成的苯并二氢萘产物在苯甲基和乙烯基位置均具有显着的H / D交换。3的偶合最显着的碳同位素效应 在色烯产物的α-烯烃碳上观察到5-二甲氧基苯酚与4-甲氧基肉桂醛(C(2)= 1.067)。3,5-二甲氧基苯酚与对位取代的p -XC 6 H 4 CH = CHCHO表现出线性相关性,并具有吸电子基团(ρ= +1.5; X = OCH 3,CH 3,H,F,Cl)的强促进作用。通过催化偶合法合成了几种具有生物活性的色酮衍生物。该催化方法提供了一种方便的合成方
Synthesis of Indolizines via Reaction of 2-Substitued Azaarenes with Enals by an Amine-NHC Relay Catalysis
作者:Hongxian Li、Xiangmin Li、Yang Yu、Jianjun Li、Yuan Liu、Hao Li、Wei Wang
DOI:10.1021/acs.orglett.7b00566
日期:2017.4.21
A metal-free catalytic strategy for the facile synthesis of biologically relevant molecular architectures indolizines and imidazopyridines has been developed. The process is promoted by amine and N-heterocyclic carbene (NHC) relay catalysis via Michael addition-[3 + 2] fusion of simple azaarenes and α,β-unsaturatedaldehydes. The preparative power is demonstrated in the synthesis of anxiolytic drug
Herein, an efficient route to enantioenriched organosilanes, containing two consecutive stereogenic centers, from enals and β‐silyl enones under carbene organocatalysis is described. Under mild reaction conditions, this transition‐metal‐free strategy exhibits a broad substrate scope, and excellent diastereo‐ and enantioselectivity.
The traditional McFadyen–Stevensreaction requires harsh alkaline reaction conditions, thus precluding application to the synthesis of aliphatic aldehydes. Our modified McFadyen–Stevensreaction enables the transformation from the N,N-acylsulfonyl hydrazine to the corresponding aldehyde upon treatment with an imidazole–TMS imidazole combination without relying on oxidative or reductive reagents. The