Stereospecific approach to α,β-disubstituted nitroalkenes via coupling of α-bromonitroalkenes with boronic acids and terminal acetylenes
摘要:
(Z)-alpha-Bromo-beta-substituted nitroethylenes undergo facile Suzuki coupling with aryl, heteroaryl, and vinylboronic acids in the presence of Pd(PPh3)(4) as catalyst to afford (E)-alpha,beta-disubstituted nitroethylenes in high yield (up to 95%) and complete specificity. Similar coupling of alpha-bromonitroethylenes with terminal acetylenes (Sonogashira coupling) provides a novel route to (E)-nitroenynes. These Pd-catalyzed coupling methods offer a convenient and stereospecific entry into a diverse array of synthetically and biologically useful alpha,beta-disubstituted nitroethylenes. (c) 2007 Elsevier Ltd. All rights reserved.
Stereospecific approach to α,β-disubstituted nitroalkenes via coupling of α-bromonitroalkenes with boronic acids and terminal acetylenes
作者:Madhu Ganesh、Irishi N.N. Namboothiri
DOI:10.1016/j.tet.2007.09.012
日期:2007.11
(Z)-alpha-Bromo-beta-substituted nitroethylenes undergo facile Suzuki coupling with aryl, heteroaryl, and vinylboronic acids in the presence of Pd(PPh3)(4) as catalyst to afford (E)-alpha,beta-disubstituted nitroethylenes in high yield (up to 95%) and complete specificity. Similar coupling of alpha-bromonitroethylenes with terminal acetylenes (Sonogashira coupling) provides a novel route to (E)-nitroenynes. These Pd-catalyzed coupling methods offer a convenient and stereospecific entry into a diverse array of synthetically and biologically useful alpha,beta-disubstituted nitroethylenes. (c) 2007 Elsevier Ltd. All rights reserved.
Enantioselective access to tetrahydropyrano[2,3- c ]pyrazoles via an organocatalytic domino Michael-hydroalkoxylation reaction
作者:Nirmal K. Rana、Rupesh K. Jha、Harshit Joshi、Vinod K. Singh
DOI:10.1016/j.tetlet.2017.04.059
日期:2017.5
An asymmetricdomino Michael-hydroalkoxylation reaction of trans-α-alkynyl-nitroolefins with N-arylpyrazolinones has been accomplished using a chiral bifunctional squaramide catalyst. Under the organocatalytic method, a broad range of tetrahydropyrano[2,3-c]pyrazoles with an exocyclic alkene at the C-6 position were prepared in high yields and excellent stereoselectivities. The presence of an exocyclic
反式-α-炔基-硝基烯烃与N-芳基吡唑啉酮类的不对称多米诺迈克尔-氢化烷氧基化反应已使用手性双功能方酰胺催化剂完成。在有机催化方法下,可以高产率和出色的立体选择性制备各种在C-6位带有环外烯烃的四氢吡喃并[2,3- c ]吡唑。吡喃并吡唑中存在环外双键和硝基为进一步的结构转化提供了广阔的空间。