College of Chemistry and Molecular Engineering, School of Life Sciences , Zhengzhou University , No. 100 of Science Road , Zhengzhou , Henan 450001 , P. R. China.
Shandong Qiaochang Modern Agriculture Co., Ltd , No. 1181 Huanghe 12 Road , Binzhou , Shandong 256600 , P. R. China.
J Org Chem. 2018 Apr 6;83(7):3657-3668. doi: 10.1021/acs.joc.8b00013. Epub 2018 Mar 19.
A series of novel ruthenium(II) complexes supported by a symmetrical NNN ligand were prepared and fully characterized. These complexes exhibited good performance in transfer hydrogenation to form new C-C bonds using alcohols as the alkylating agents, generating water as the only byproduct. A broad range of substrates, including (hetero)aryl- or alkyl-ketones and alcohols, were well tolerated under the optimized conditions. Notably, α-substituted methylene ketones were also investigated, which afforded α-branched steric hindrance products. A potential application of α-alkylation of methylene acetone to synthesize donepezil was demonstrated, which provided the desired product in 83% yield. Finally, this catalytic system could be applied to a one-pot double alkylation procedure with sequential addition of two different alcohols. The current protocol is featured with several characteristics, including a broad substrate scope, low catalyst (0.50 mol %) loadings, and environmental benignity.
一系列新型钌（II）配合物由对称的 NNN 配体支持，并进行了充分的表征。这些配合物在使用醇作为烷基化试剂的转移氢化中形成新的 C-C 键方面表现出良好的性能，仅生成水作为唯一的副产物。在优化条件下，广泛的底物，包括（杂）芳基或烷基酮和醇，都能很好地耐受。值得注意的是，还研究了α-取代的亚甲基酮，其得到了α-支化的空间位阻产物。亚甲基丙酮的α-烷基化在合成多奈哌齐中的潜在应用得到了证明，该反应以 83%的收率得到了所需产物。最后，该催化体系可应用于一锅两步烷基化程序，顺序加入两种不同的醇。该方法具有以下几个特点，包括广泛的底物范围、低催化剂（0.50 mol %）负载和环境友好性。
