开发能够使一氧化二氮 (N 2 O) 重新增值的催化化学工艺是减轻其排放1,2,3,4,5,6造成的环境威胁的有吸引力的策略。传统上,N 2 O 被认为是一种惰性分子,由于其活化所需的苛刻条件(>150 °C,50-200 bar) 7,8,有机化学家难以将其用作氧化剂或 O 原子转移试剂。 9,10,11。在这里,我们报告了在温和条件下(室温,1.5-2 bar N 2 O)将 N 2 O 插入 Ni-C 键,从而提供有价值的酚并释放良性 N 2. 这种从根本上不同的有机金属 C-O 键形成步骤不同于当前基于还原消除的策略,并为将芳基卤化物转化为苯酚提供了另一种催化方法。该过程通过用于 Ni 中心的基于联吡啶的配体进行催化。该方法稳健、温和且选择性高,能够适应碱基敏感功能,并允许从密集官能化的芳基卤化物合成苯酚。尽管该协议没有提供缓解 N 2 O 排放的解决方案,但它代表了将丰富的 N 2
三个含有噻吩或四氢呋喃杂环基团的 β-二酮亚氨基前配体 H 2 L 1、H 2 L 2和 H L 3 (MeC(NDipp)CHC( Me )N(CH 2 ) n -2-(HCG), HCG = C 4 H 2 S, n = 2, L 1 ; n = 1, L 2 ; HCG = C 4 H 7 O, n = 1, L 3 ; Dipp = 2,6- i Pr 2 C 6 H 3), 已经开发了。不寻常的N , N , C三齿 β-二酮亚氨基稀土金属单烷基配合物L 1 RE(CH 2 SiMe 3 )(thf) (RE = Y ( 1a ), Er ( 1b ), Yb ( 1c ), Lu ( 1d ) , thf = 四氢呋喃) 和L 2 Yb(CH 2 SiMe 3 )(thf) ( 2c ) 通过 RE(CH 2 SiMe 3 ) 3 (thf) 2与 H 2 L 1和 H的反应出乎意料地实现2
Oxygenation reactions with molecular oxygen (O2) as the oxygen source provides a green and straightforward strategy for the construction of O‐containing compounds. Demonstrated here is a novel N‐heterocyclic carbene (NHC) catalyzed oxidative transformation of simple and readily available organic halides into valuable esters through the incorporation of O‐atomsfromO2. Mechanistic studies prove that
Aldehyde effect and ligand discovery in Ru-catalyzed dehydrogenative cross-coupling of alcohols to esters
作者:Xiaolin Jiang、Jiahui Zhang、Dongmei Zhao、Yuehui Li
DOI:10.1039/c8cc10315a
日期:——
ligands for dehydrogenation of alcohols. Accordingly, hybrid multi-dentate ligands were discovered based on an oxygen-transfer alkylation of PNP ligands by aldehydes. The relevant Ru-PNN(PO) system provided the desired unsymmetrical esters in good yields via acceptorless dehydrogenation of alcohols. Hydrogen bonding interactions between the phosphine oxide moieties and alcohol substrates likely assisted
Oxidative dimerization of primary alcohols with 2-butanone in the presence of an amino alcohol-based Ir bifunctional catalyst was accomplished for the first time. The reaction proceeds with 1-2 mol% of the catalyst and 0.3 mol equivalents of K2CO3 in 2-butanone at room temperature to give the corresponding dimeric esters in 30-93% yield.
Easy access to benzylic esters directly from alkyl benzenes under metal-free conditions
作者:Ganesh Majji、Srimanta Guin、Anupal Gogoi、Saroj Kumar Rout、Bhisma K. Patel
DOI:10.1039/c3cc40832a
日期:——
An efficient metal free protocol has been developed for the synthesis of benzylic esters via a cross dehydrogenative coupling (CDC) involving alkylbenzene(s) as a self- or as a cross-coupling partner(s) via the intermediacy of Ar–COOH and the benzylic carbocation obtained from the other half of the alkylbenzene; both symmetrical as well as unsymmetrical esters can be prepared using Bu4NI and TBHP.
Efficient and Simple Approaches Towards Direct Oxidative Esterification of Alcohols
作者:Ritwika Ray、Rahul Dev Jana、Mayukh Bhadra、Debabrata Maiti、Goutam Kumar Lahiri
DOI:10.1002/chem.201403786
日期:2014.11.17
The present article describes novel oxidative protocols for directesterification of alcohols. The protocols involve successful demonstrations of both “cross” and “self” esterification of a wide variety of alcohols. The cross‐esterification proceeds under a simple transition‐metal‐free condition, containing catalytic amounts of TEMPO (2,2,6,6‐tetramethyl‐1‐piperidinyloxy)/TBAB (tetra‐n‐butylammonium