借用氢或氢自动转移方法是构建碳-碳键的优雅且可持续或绿色的概念。在这个概念中,可以从几乎不使用且难以消化的生物质(例如木质纤维素)中获得的醇被用作烷基化试剂。一个特别具有挑战性的烷基化是未活化的酯和酰胺。仅使用基于铱和钌的贵金属催化剂来完成这些反应。在此,我们报告了醇对未活化酰胺和酯的第一个贱金属催化的 α-烷基化反应。我们实验室最近开发的钳形配体稳定的钴配合物可以非常有效地催化这些反应。预催化剂可以很容易地从市售的起始材料以多克规模合成,并且在碱性反应条件下自活化。这种 Co 催化剂类别还能够介导酯和酰胺的烷基化反应。此外,我们应用该方法合成酮并将醇转化为由两个碳原子拉长的醛。
General and Mild Cobalt-Catalyzed C-Alkylation of Unactivated Amides and Esters with Alcohols
作者:Nicklas Deibl、Rhett Kempe
DOI:10.1021/jacs.6b06448
日期:2016.8.31
The borrowinghydrogen or hydrogen autotransfer methodology is an elegant and sustainable or green concept to construct carbon-carbon bonds. In this concept, alcohols, which can be obtained from barely used and indigestible biomass, such as lignocellulose, are employed as alkylating reagents. An especially challenging alkylation is that of unactivated esters and amides. Only noble metal catalysts based
借用氢或氢自动转移方法是构建碳-碳键的优雅且可持续或绿色的概念。在这个概念中,可以从几乎不使用且难以消化的生物质(例如木质纤维素)中获得的醇被用作烷基化试剂。一个特别具有挑战性的烷基化是未活化的酯和酰胺。仅使用基于铱和钌的贵金属催化剂来完成这些反应。在此,我们报告了醇对未活化酰胺和酯的第一个贱金属催化的 α-烷基化反应。我们实验室最近开发的钳形配体稳定的钴配合物可以非常有效地催化这些反应。预催化剂可以很容易地从市售的起始材料以多克规模合成,并且在碱性反应条件下自活化。这种 Co 催化剂类别还能够介导酯和酰胺的烷基化反应。此外,我们应用该方法合成酮并将醇转化为由两个碳原子拉长的醛。
Nickel-catalyzed <i>C</i>-alkylation of thioamide, amides and esters by primary alcohols through a hydrogen autotransfer strategy
A simple catalyst of Ni(OAc)2 and P(t-Bu)3 enables selective C-alkylation of thioacetamides and primary acetamide with alcohols for the first time. Monoalkylation of thioamides, amides and t-butyl esters occurs in excellent yields (>95%). Mechanistic studies reveal that the reaction proceeds via a hydrogen autotransfer pathway.
Ni-Catalyzed α-Alkylation of Unactivated Amides and Esters with Alcohols by Hydrogen Auto-Transfer Strategy
作者:Siba P. Midya、Jagannath Rana、Jayaraman Pitchaimani、Avanashiappan Nandakumar、Vedichi Madhu、Ekambaram Balaraman
DOI:10.1002/cssc.201801443
日期:2018.11.23
A transition‐metal‐catalyzedborrowinghydrogen/hydrogen auto‐transfer strategy allows the utilization of feedstock alcohols as an alkylating partner, which avoids the formation of stoichiometric salt waste and enables a direct and benign approach for the construction of C‐N and C−C bonds. In this study, a nickel‐catalyzedα‐alkylation of unactivated amides and ester (tert‐butyl acetate) is carried
Mn-catalyzed C-alkylation of amides and tert-butyl acetate using alcohols as alkylating agents is reported. This approach exhibits a broad substrate scope providing the C(α)-alkylated amides in good yields via hydrogen auto-transfer strategy.
Bidentate Ru(II)‐NC Complexes as Catalysts for
<i>α</i>
‐Alkylation of Unactivated Amides and Esters
作者:Dawei Gong、Bowen Hu、Weiwei Yang、Dafa Chen
DOI:10.1002/cctc.201901319
日期:2019.10.7
Five Ru(II)‐NC complexes were tested as catalysts for α‐alkylation of unactivated amides using alcohols as alkylating agents, and complex (C5H4N)‐(C6H4)}RuCl(CO)(PPh3)2 (1) showed the highest activity. With 0.5 mol% catalyst loading, a series of α‐alkylated amides were isolated at 80 °C within 6 hours. Furthermore, under similar conditions, complex 1 was also active for α‐alkylation of unactivated
测试了五种Ru(II)-NC配合物作为使用醇作为烷基化剂的未活化酰胺的α-烷基化的催化剂,配合物(C 5 H 4 N)-(C 6 H 4)} RuCl(CO)(PPh 3)2(1)显示最高活性。在催化剂负载量为0.5 mol%的情况下,在80°C下于6小时内分离出一系列α烷基化的酰胺。此外,在相似的条件下,配合物1对未活化酯与醇的α烷基化反应也具有活性,反应时间缩短至1.5小时。1的催化性能 与报道得最好的催化剂相当。