Transition-metal-free C–C bond cleavage and formation: efficient synthesis of 2,3-diarylimidazo[1,2-α]pyridines from 2-aminopyridines and alkynoates
作者:Zhengwang Chen、Yuelu Wen、Guotian Luo、Min Ye、Qinghao Wang
DOI:10.1039/c6ra19291b
日期:——
A highly efficient transition-metal-free cyclization reaction for the synthesis of 2,3-diarylimidazo[1,2-α]pyridines is described. A variety of substituted 2-aminopyridines and alkynoates are compatible under the standard conditions. This protocol is marked by the cleavage of a C–C bond and the formation of a new Csp2–Csp2 bond under transition-metal-free conditions.
efficient asymmetric cascade reaction between alkynyl esters and allylic alcohols has been realized. Key to success was the combination of a hydroalkoxylation reaction catalyzed by a π‐acidic gold(I) complex with a Claisen rearrangement catalyzed by a chiral Lewis acidic N,N′‐dioxide–nickel(II) complex. A range of acyclic α‐allyl β‐keto esters were synthesized in high yields (up to 99 %) with good
Ruthenium-Catalyzed Asymmetric [2 + 2] Cycloadditions between Chiral Acyl Camphorsultam-Substituted Alkynes and Bicyclic Alkenes
作者:Jordan Goodreid、Karine Villeneuve、Emily Carlson、William Tam
DOI:10.1021/jo501594g
日期:2014.11.7
Ruthenium-catalyzedasymmetric [2 + 2] cycloadditionsbetweenchiralacyl camphorsultam-functionalized alkynes and bicyclicalkenes were examined, providing adducts with complete exo stereoselectivity in good overall yield and enantioselectivity (up to 99% and 166:1, respectively), as well as appreciable diastereoselectivity (up to 163:1). The diastereoselectivity showed dependence on the solvent and
Metal‐Free Oxidative [5+1] Cyclization of 1,5‐Enynes for the Synthesis of Pyrazine 1‐Oxide
作者:Xiao‐Feng Xia、Mingming Zhao、Wei He、Lianghua Zou、Xinxin San、Dawei Wang
DOI:10.1002/adsc.202000756
日期:2020.9.8
A chemo‐selective nitrosylation of 1,5‐enynes via a sequence of NO radical incorporation and intramolecular radical cyclization was reported. The formation of two C−N bonds and one C−O bond make this [5+1] cycloaddition reaction an efficient approach to synthesize pyrazine 1‐oxides in moderate to good yields. Metal‐free, short reaction time and mild conditions render this strategy more practical, eco‐friendly
Starting from simple anilines and ester arylpropiolates, an efficient one-pot synthesis of 2-arylindole-3-carboxylate derivatives has been developed through copper-mediated sequential hydroamination and cross-dehydrogenative coupling (CDC) reaction. The initial hydroamination of anilines to ester arylpropiolates in benzene can proceed in a stereoselective manner to give ester (Z)-3-(arylamino)acrylates