Bifunctional N-Heterocyclic Carbene Catalyzed [3+4] Annulation of Enals and Aurones
作者:Zhi-Qin Liang、Zhong-Hua Gao、Wen-Qiang Jia、Song Ye
DOI:10.1002/chem.201405828
日期:2015.1.26
Bifunctional N‐heterocyclic carbenes with a free hydroxy group are demonstrated as efficient catalysts for the [3+4] annulation of enals with aurones to give the corresponding benzofuran‐fused ε‐lactones in good yields with good diastereoselectivities and excellent enantioselectivities. Control experiments reveal that the [3+4] cycloadducts are kinetically favored and could be transformed to the thermodynamically
A regioselective approach for construction of 5-membered and 6-membered flavonoid is established by Pd catalyzed carbonylative cyclization of 2-iodophenol with terminal alkynes using different amine bases under mild reaction condition. The catalytic experiments found that piperazine preferentially accelerate 6-endo cyclization, and triethylamine mediated Pd catalyzed 5-exo cyclization. Under optimized
Highly Regio‐, Diastereo‐, and Enantioselective Synthesis of Tetrahydroazepines and Benzo[
<i>b</i>
]oxepines through Palladium‐Catalyzed [4+3] Cycloaddition Reactions
作者:Barry M. Trost、Zhijun Zuo
DOI:10.1002/anie.201911537
日期:2020.1.13
A novel Pd0 -catalyzed asymmetric [4+3] annulation reaction of two readily accessible starting materials has been developed for building seven-membered heterocyclic architectures. The potential [3+2] side pathway could be suppressed though fine tuning of the conditions. A broad scope of cycloaddition donors and acceptors participated in the transformation with excellent chemo-, regio-, diastereo-,
Palladium-Catalyzed Diastereo- and Enantioselective [3 + 2] Cycloaddition of Vinylcyclopropanes with Azadienes: Efficient Access to Chiral Spirocycles
作者:Kai Liu、Jianfeng Yang、Xiaoxun Li
DOI:10.1021/acs.orglett.0c04062
日期:2021.2.5
azadienes (BDAs) have been widely used as four-atom synthons in transition-metal-mediated cycloaddition reactions, while the exploitation of their reactivity as a two-atom unit to construct spirocycles is still underdeveloped. Herein, we reported the first palladium(0)-catalyzed diastereo- and enantioselective [3 + 2] annulation of vinylcyclopropanes (VCPs) and BDAs. This transformation is featured with
Cascade Cyclization of Azadienes with Difluoroenoxysilanes: A One-Pot Formal [4 + 2] Approach to Fluorinated Polyfused Heterocycles
作者:Jinshan Li、Saimei Liu、Rong Zhong、Yaqi Yang、Jinjing Xu、Jianguo Yang、Hanfeng Ding、Zhiming Wang
DOI:10.1021/acs.orglett.1c03745
日期:2021.12.17
fluorinated polyfused heterocycles via the cascade cyclization of azadienes and difluoroenoxysilanes has been developed, leading to the facile construction of fluorinated benzofuro[3,2-b]pyridines, 5H-indeno[1,2-b]pyridines, and 5,6-dihydrobenzo[h]quinolines. This one-pot formal [4 + 2] approach involves 1,4-difluoroalkylation, desulfonylation, cyclization, and dehydrated and dehydrofluorinated aromatization
通过氮杂二烯和二氟烯氧基硅烷的级联环化,TfOH 促进了氟化多稠杂环的合成,从而轻松构建了氟化苯并呋喃[3,2- b ]吡啶、5 H-茚并[1,2- b ]吡啶, 和 5,6-二氢苯并[ h ]喹啉。这种一锅法 [4 + 2] 方法涉及 1,4-二氟烷基化、脱磺酰化、环化以及脱水和脱氟化氢芳构化,代表了二氟烯氧基硅烷在级联转化中的首次应用。此外,该方法通过合成具有强效拓扑异构酶抑制活性的生物活性分子的三种氟类似物而突出。