N-heterocycle carbene (NHC)-ligated cyclopalladated N,N-dimethylbenzylamine: a highly active, practical and versatile catalyst for the Heck–Mizoroki reaction
作者:Guang-Rong Peh、Eric Assen B. Kantchev、Chi Zhang、Jackie Y. Ying
DOI:10.1039/b821892g
日期:——
NHC-Pd catalyst, a triflate was coupled with diverse acrylate derivatives (nitrile, tert-butyl ester and amides) and styrene derivatives. The use of excess (>2 equiv.) of the aryl bromide and tert-butyl acrylate leads to mixture of tert-butyl β,β-diarylacrylate and tert-butyl cinnamate derivatives depending on the substitution pattern of the aryl bromide. Electron rich m- and p-substituted arylbromides
催化剂的发展不仅促进了催化方案在学术和工业实验室中的广泛传播,该催化剂不仅具有高活性,而且还易于使用,对湿气,空气和长期储存稳定,易于大规模制备。在本文中,我们描述了由环钯N,N-二甲基苄胺(dmba)与N杂环卡宾1,3-双(甲磺酰基)咪唑-2-亚基(IMes)连接而介导的Heck-Mizoroki反应的方案标准。可以通过三组分,顺序,一锅法反应制得约100 g规模的预催化剂。N,N-二甲基苄胺,PdCl 2和IMes·HCl回流乙腈在空气中存在K 2 CO 3的情况下。这种单组分催化剂对空气,湿气和长期储存稳定,并且可以方便地作为储备溶液分配到NMP中。它介导0.1-2 mol%范围的试剂级NMP中的一系列芳基和杂芳基溴的Heck-Mizoroki反应,而无需严格的无水技术或手套箱,甚至在空气中也具有活性。该催化剂能够实现很高的催化活性(TON高达5.22×10 5),用于偶联失活的芳基溴化物,对溴苯甲醚,以t
TiCl4-mediated olefination of aldehydes with acetic acid and alkyl acetates: a stereoselective approach to (E)-α,β-unsaturated carboxylic acids and esters
the preparation of α,β-unsaturated carboxylic acids and corresponding esters with (E)-stereoselectivity via the TiCl4-mediated olefination of aldehydes. The method, which uses readily available aceticacid or its alkylesters as active methylene partners, is more flexible and complementary to conventional routes in the preparation of (E)-cinnamic acid derivatives.