One-pot synthesis of N-tert-butyl amides from alcohols, ethers and esters using ZnCl2/SiO2 as a recyclable heterogeneous catalyst
摘要:
ZnCl2/SiO2 has been found to be an efficient and reusable catalyst for conversion of alcohols, ethers and esters to corresponding amides via the Ritter reaction in high yield. It was found that benzonitrile reacted with tert-butyl acetate faster than the other sources of tert-butyl carbocation. (C) 2011 Elsevier B.V. All rights reserved.
Herein described is a nickel-catalyzed aminocarbonylation of aryl/alkenyl/allyl (pseudo)halides with isocyanides, providing aryl/alkenyl/allyl amides in 41% to 92% yields. Functional groups such as F, Cl, OMe, and heteroaromatic rings are compatible in the reaction. A Ni(0)/Ni(II) catalytic cycle is proposed based on preliminary experiments and previous literature. The reaction features readily available
Amides can be prepared from allyl or benzyl halides and primary or secondary amines, using Pd(O) catalyst under CO pressure, in a one-pot synthesis. The reaction proceeds through the acyl palladium halide formation which undergoes an acylic nucleophilic substitution from the amine. (C) 2009 Elsevier Ltd. All rights reserved.
New synthesis of nitrogen heterocycles through amide-directed hydrocarbonylation of alkenamides catalyzed by rhodium complexes
作者:Iwao Ojima、Anna Korda、William R. Shay
DOI:10.1021/jo00006a013
日期:1991.3
Amide-directed hydrocarbonylation of 3-butenamide (1) catalyzed by rhodium complexes such as RhCl(PPh3)3, RhCl(CO)(PPh3)2, HRh(CO)(PPh3)3, and Rh4(CO)12 gives a mixture of 3,4-dihydro-2-pyridone (2), 4-methyl-3-pyrrolin-2-one (3), and a unique heterodimer, 6-(4-methyl-2-oxo-3-pyrrolin-1-yl)-2-piperidone (4). Dihydropyridone (2) is obtained in 88% yield with 98% selectivity by using HRh(CO)(PPh)3-dppb (2 equiv) catalyst system while 4 is yielded in 90% yield with 94% selectivity with the use of RhCl(PPh3)3-P(OPh)3 (10 equiv) as the catalyst. Control experiments revealed that this crossed coupling only proceeds in the copresence of rhodium catalyst, carbon monoxide, and hydrogen. The reactions of N-benzyl-3-butenamide (1a) gives a mixture of 1-benzyldihydropyridone (2a), 1-benzyl-4-methylpyrrolinone (3a), and 1-benzyl-6-formyl-3,4-dihydropyridone (5) and its 5-formyl isomer (6). The formation of 5 and 6 is suppressed by the addition of PPh3, and 2a is selectively isolated (72%) in the reaction using RhCl(CO)(PPh3)2-PPh3 (20 equiv) as the catalyst. The hydroformylation of 2a catalyzed by RhCl(PPh3)3 gives 5 in 80% isolated yield. The reaction of N-tert-butyl-3-butenamide (1b) gives a nearly 1:1 mixture of 1-tert-butyl-4-methylpyrrolinone (3b) and uncyclized N-tert-butyl-4-formylbutanamide (7) accompanied by a small amount of 1-tert-butyldihydropyridone (2b). In the reaction of N-trityl-3-butenamide (1c), no dihydropyridone (2c) was formed, and a mixture of 1-trityl-4-methylpyrrolinone (3c) (major) and N-trityl-4-formylbutanamide (8) (minor) is yielded. The reaction of 4-pentenamide gives 4-methyl-3,4-dihydro-2-pyridone (9) exclusively regardless of the structure of the rhodium catalysts used. Possible mechanisms for these reactions are discussed.
One-pot synthesis of N-tert-butyl amides from alcohols, ethers and esters using ZnCl2/SiO2 as a recyclable heterogeneous catalyst
作者:Fatemeh Tamaddon、Fatemeh Tavakoli
DOI:10.1016/j.molcata.2011.01.013
日期:2011.3
ZnCl2/SiO2 has been found to be an efficient and reusable catalyst for conversion of alcohols, ethers and esters to corresponding amides via the Ritter reaction in high yield. It was found that benzonitrile reacted with tert-butyl acetate faster than the other sources of tert-butyl carbocation. (C) 2011 Elsevier B.V. All rights reserved.
Remote Site-Selective C(sp<sup>3</sup>)–H Monodeuteration of Unactivated Alkenes <i>via</i> Chain-Walking Strategy
aided by native directing groups, using readily available pinacolborane (HBpin) and D2O as H– and D+ sources, respectively. Significantly, this tactic offers a complementary pattern to conventional hydrodeuteration methods that adduct H–D, or its surrogate, to unsaturated bonds. Both experimental data and density functional theory (DFT) studies demonstrated the critical role of the directing group in guiding
在远端 C(sp 3 )–H 键处安装氘原子是一项长期存在的合成挑战。通过链步策略和转移氢氘化的协同组合,我们在天然定向基团的帮助下,使用现成的频哪醇硼烷 (HBpin) 和 D 2 O ,展示了远端 C(sp 3 )–H 位点未活化烯烃的远程转移氢氘化作为 H –和 D +来源,分别。值得注意的是,这种策略为传统的加氢氘化方法提供了一种补充模式,该方法将 H-D 或其替代物加合物到不饱和键上。实验数据和密度泛函理论 (DFT) 研究都证明了引导基团在引导烯烃异构化过程中的关键作用。DFT 计算表明,在烯烃插入和异构化步骤中,是原位生成的 Ni(II)-氢化物而不是 Ni(I)-氢化物作为活性中间体发挥作用。