Asymmetric Guerbet Reaction to Access Chiral Alcohols
作者:Kun Wang、Lin Zhang、Weijun Tang、Huaming Sun、Dong Xue、Ming Lei、Jianliang Xiao、Chao Wang
DOI:10.1002/anie.202003104
日期:2020.7.6
example of an asymmetric Guerbet reaction has been developed. Using commercially available, classic Noyori RuII‐diamine‐diphosphine catalysts, well‐known in asymmetric hydrogenation, racemic secondary alcohols are shown to couple with primary alcohols in the presence of a base, affording new chiral alcohols with enantiomeric ratios of up to 99:1. Requiring no reducing agents, the protocol provides an easy
A new Mn‐catalyzed alkylation of secondary alcohols with non‐activated alcohols is presented. The use of a stable and well‐defined manganese pincer complex, stabilized by a PNN ligand, together with a catalytic amount of base enabled the conversion of renewable alcohol feedstocks to a broad range of higher‐value alcohols in good yields with water as the sole byproduct. The strategy eliminates the need
Switchable β-alkylation of Secondary Alcohols with Primary Alcohols by a Well-Defined Cobalt Catalyst
作者:Bedraj Pandey、Shi Xu、Keying Ding
DOI:10.1021/acs.organomet.1c00147
日期:2021.5.10
β-alkylation of secondaryalcohols with primaryalcohols to selectively generate alcohols by a well-defined Co catalyst is presented. Remarkably, a low catalyst loading of 0.7 mol % can be employed for the reaction. More significantly, this study represents the first Co-catalyzed switchable alcohol/ketone synthesis by simply manipulating the reaction parameters. In addition, the transformation is environmentally
Ruthenium-Catalyzed β-Alkylation of Secondary Alcohols and α-Alkylation of Ketones via Borrowing Hydrogen: Dramatic Influence of the Pendant <i>N</i>-Heterocycle
respectively. These complexes were tested as catalysts for β-alkylation of secondaryalcohols with primary alcohols, and 3 shows the highest activity, suggesting the thiazolyl ring participates in the catalytic process. Furthermore, 3 is an excellent catalyst for α-alkylation of ketones with primary alcohols. Various α-alkylated ketones were synthesized in high yields, by using 0.05 mol % 3 and 0.25 equiv
Unusual C–O bond cleavage of aromatic ethers in ruthenium complexes bearing a 2-alkoxypyridyl fragment
作者:Danfeng Deng、Bowen Hu、Min Yang、Dafa Chen
DOI:10.1039/c9dt03020d
日期:——
In contrast, in the presence of KOH, the reaction switches to an SNAr chemistry. The bidentate ruthenium isomers [CH3O-C5H3N-C5H4N}RuH(CO)(PPh3)2]Cl (4a and 4b) could undergo similar C–O cleavage, affording product O-C5H3N-C5H4N}RuH(CO)(PPh3)2 (5), which reacted with HCl to generate complex [HO-C5H3N-C5H4N}RuH(CO)(PPh3)2]Cl (6). These complexes were tested as catalysts for β-alkylation of secondary
两种四齿(NNOP)钌产物[RO-C 5 H 3 N-C 5 H 3 N-CH(O)-C 6 H 4 -PPh 2 } Ru(CO)(PPh 3)] Cl(1:R = Me ;3:R = Ph)是通过相应的配体与RuHCl(PPh 3)3(CO)的反应分离的。当在THF中加热时,通过C–OMe键裂解,复合物1也可以转化为2。研究了复合物1中异常C–O裂解的机理,结果表明它是S N2机构通过迹线的攻击量的中性ħ 2 O.在此相反,在KOH的存在下,将反应切换到一个S Ñ氩化学。双齿钌异构体[CH 3 O-C 5 H 3 N-C 5 H 4 N} RuH(CO)(PPh 3)2 ] Cl(4a和4b)可以进行类似的C-O裂解,得到产物OC 5 H 3 N-C 5 H 4 N} RuH(CO)(PPh 3)2(5),其与HCl反应生成络合物[HO-C 5H 3 N-C 5 H 4 N} RuH(CO)(PPh