Selective Construction of C−C and C=C Bonds by Manganese Catalyzed Coupling of Alcohols with Phosphorus Ylides
作者:Xin Liu、Thomas Werner
DOI:10.1002/adsc.202001209
日期:2021.2.16
manganese catalyzed coupling of alcohols with phosphorus ylides. The selectivity in the coupling of primary alcohols with phosphorus ylides to form carbon‐carbon single (C−C) and carbon‐carbon double (C=C) bonds can be controlled by the ligands. In the conversion of more challenging secondary alcohols with phosphorus ylides the selectivity towards the formation of C−C vs. C=C bonds can be controlled by the
The One-Pot Wittig Reaction: A Facile Synthesis of α,β-Unsaturated Esters and Nitriles by Using Nanocrystalline Magnesium Oxide
作者:Boyapati M. Choudary、Koosam Mahendar、M. Lakshmi Kantam、Kalluri V. S. Ranganath、Taimur Athar
DOI:10.1002/adsc.200606001
日期:2006.9
Nanocrystalline magnesium oxide was found to be an effective heterogeneous, solid base catalyst for the one-pot Wittig reaction to afford α,β-unsaturatedesters and nitriles in excellent yields with high E-stereoselectivity in the presence of triphenylphosphine under mild conditions.
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
3,5-Bis(trifluoromethyl)phenyl Sulfones for the Highly Stereoselective Julia–Kocienski Synthesis of α,β-Unsaturated Esters and Weinreb Amides
作者:Diego A. Alonso、Mónica Fuensanta、Enrique Gómez-Bengoa、Carmen Nájera
DOI:10.1002/ejoc.200800041
日期:2008.6
l)phenyl (BTFP) sulfones tert-butyl α-(BTFPsulfonyl)acetate (4) and Weinreb α-(BTFPsulfonyl)acetamide (5) have successfully been employed in the Julia–Kocienski olefination of aldehydes with K2CO3 as the base at 120 °C in DMF under solid/liquid phase-transfer catalysis conditions to afford α,β-unsaturated esters and Weinrebamides, respectively. The corresponding products were obtained in good yields
1,4-Addition of arylboronic acids to β-aryl-α,β-unsaturated ketones and esters catalyzed by a rhodium(I)–chiraphos complex for catalytic and enantioselective synthesis of selective endothelin A receptor antagonists
An enantioselective synthesis of acyclic β-diaryl ketones and esters via 1,4-addition of arylboronic acids to β-aryl-α,β-unsaturatedketones or esters is described. The complex in situ prepared from [Rh(nbd)2]BF4 and chiraphos was found to be an excellent catalyst to achieve high enantioselectivities in a range of 83–89% ee for the ketone derivatives and 78–94% ee for tert-butyl β-arylacrylate derivatives