Bicyclic Bridgehead Phosphoramidite-Based Hybrid Diphosphorus Ligands: Design, Synthesis, and Application in Catalytic Asymmetric Hydrogenation
作者:Hong-Quan Du、Xiang-Ping Hu
DOI:10.1021/acs.orglett.1c02978
日期:2021.10.1
A strategy for chiral ligand design has been developed that allows for incorporation of an achiral bicyclic bridgehead phosphoramidite to generate a class of hybrid diphosphorus ligands for high activity and asymmetric control. Using this concept, a series of chiral phosphine–phosphoramidite ligands bearing the sole chirality at the ligand backbone have been prepared and successfully employed in the
Cleavage of C–C Bonds for the Synthesis of C2-Substituted Quinolines and Indoles by Catalyst-Controlled Tandem Annulation of 2-Vinylanilines and Alkynoates
作者:Jixiang Ni、Yong Jiang、Zhenyu An、Rulong Yan
DOI:10.1021/acs.orglett.8b00260
日期:2018.3.16
and alkynoates through C–C bond cleavage is developed. With these general methods, 2-substituted indoles and quinolines can be accessed via tandem Michael addition and cyclization with no requirement of oxidant. This strategy not only provides a method for the synthesis C2-substituted indoles in good yields through the simultaneous cleavage of C═C and C≡C bonds under metal-free conditions but also provides
tert-Butyl nitrite (TBN) as the N atom source for the synthesis of substituted cinnolines with 2-vinylanilines and a relevant mechanism was studied
作者:XiaoBo Pang、LianBiao Zhao、DaGang Zhou、Ping Yong He、ZhenYu An、Ji Xiang Ni、RuLong Yan
DOI:10.1039/c7ob01553d
日期:——
A green method to synthesize cinnolines by 6π electrocyclic reaction with alkenyl amines and TBN has been developed. TBN plays a dual role both as the nitrogen atom source and oxidant in this procedure. Relevant mechanism experiments reveal the reaction proceeds through electrocyclic reaction and with diazo hydroxide as a key intermediate.
Palladium-catalyzed cascade reactions of alkene-tethered carbamoyl chlorides with <i>N</i>-tosyl hydrazones: synthesis of alkene-functionalized oxindoles
A palladium-catalyzed cascade reaction of alkene-tethered carbamoylchlorides with N-tosyl hydrazones is described. It provided a new way to synthesize various alkene-functionalized oxindoles bearing an all-carbon quaternary center. The olefin moieties could serve as versatile handles for further elaboration. This transformation was highly efficient and showed good functional group tolerance.
attractive approach to valuable yet synthetically challenging benzo[b]azepines was established via palladium(II)/Lewis acid cocatalyzed oxidative [5 + 2] annulation of readily available 2-alkenylanilines and propargylic esters. The protocol features mild reaction conditions and good functional group tolerance, constituting an array of benzo[b]azepines in yields of 30–75%.
通过钯(II)/路易斯酸共催化易得的2-烯基苯胺和炔丙基酯的氧化[5 + 2]环氧化反应,建立了一种有价值的但对合成具有挑战性的苯并[ b ]氮杂苯的有吸引力的方法。该方案具有温和的反应条件和良好的官能团耐受性,构成了一系列苯并[ b ]氮杂s,产率为30–75%。