5422-47-9Relevant articles and documents
Aerobic Oxidative Cleavage and Esterification of C(OH)–C Bonds
Liu, Mingyang,Zhang, Zhanrong,Yan, Jiang,Liu, Shuaishuai,Liu, Huizhen,Liu, Zhaotie,Wang, Weitao,He, Zhenhong,Han, Buxing
supporting information, p. 3288 - 3296 (2020/10/20)
C(OH)–C bonds are widely distributed in naturally renewable biomass, such as carbohydrates, lignin, and their platform molecules. Selective cleavage and functionalization of C(OH)–C bonds is an attractive strategy in terms of producing value-added chemicals from biomass. However, effective transformation of alcohols into esters by activation of C(OH)–C bonds has not been achieved so far. Herein, for the first time, we report selective cleavage and esterification of C(OH)–C bonds, catalyzed by inexpensive copper salts, using environmentally benign oxygen as the oxidant, to afford methyl esters in excellent yields. A diverse range of phenylethanol derivatives that contain C(OH)–C bonds were effectively converted into methyl benzoates. Detailed analysis revealed that the high efficiency and selectivity resulted mainly from the fact that, in addition to the major esterification reaction, the side products (e.g., olefins and acids) were also transformed in situ into esters in the reaction system. C(OH)–C bonds are widely distributed in naturally renewable biomass. In the context of developing future biorefineries, selective cleavage and functionalization of C(OH)–C bonds are crucial and represent an attractive strategy in terms of producing value-added chemical compounds from biomass resources. In the current manuscript, we report, for the first time, an effective and selective method for the cleavage and esterification of C(OH)–C bonds of alcohols to produce esters, by using environmentally benign O2 as the terminal oxidant and inexpensive commercially available copper salts as catalysts. Furthermore, a detailed mechanistic study revealed that, in addition to the major esterification route, side products (e.g., olefins and acids), which are inevitably generated under oxidative and basic conditions, were also simultaneously converted into esters, thus significantly improving the final yields of target ester products. Native lignin represents the only naturally sustainable aromatic resource. Transformation of native lignin into valuable aromatics would make a great contribution to our planet. We report, for the first time, the effective transformation of alcohols into esters by esterification of C(OH)–C bonds, which offers a new way for the simultaneous degradation and functionalization of lignin. This reaction promotes new explorations for biomass valorization.
Nitrogen Dioxide Catalyzed Aerobic Oxidative Cleavage of C(OH)–C Bonds of Secondary Alcohols to Produce Acids
Liu, Mingyang,Zhang, Zhanrong,Song, Jinliang,Liu, Shuaishuai,Liu, Huizhen,Han, Buxing
supporting information, p. 17393 - 17398 (2019/11/11)
Stable organic nitroxyl radicals are an important class of catalysts for oxidation reactions, but their wide applications are hindered by their steric hinderance, high cost, complex operation, and separation procedures. Herein, NO2 in DMSO is shown to effectively catalyze the aerobic oxidative cleavage of C(OH)?C bonds to form a carboxylic group, and NO2 was generated in situ by decomposition of nitrates. A diverse range of secondary alcohols were selectively converted into acids in excellent yields in this transition-metal-free system without any additives. Preliminary results also indicate its applicability to depolymerize recalcitrant macromolecular lignin. Detail studies revealed that NO2 from nitrates promoted the reaction, and NO2 served as hydrogen acceptor and radical initiator for the tandem oxidative reaction.
Chemoselective Benzylation of Aldehydes Using Lewis Base Activated Boronate Nucleophiles
Hollerbach, Michael R.,Barker, Timothy J.
, p. 1425 - 1427 (2018/05/24)
A benzylation of aldehydes using primary and secondary benzylboronic acid pinacol esters is reported. Activation of the boronic ester with s-butyllithium rendered it nucleophilic toward aldehydes. The activated nucleophile chemoselectively transfers the benzyl group over the sec-butyl group, providing excellent yields of the benzylated products. 11B NMR experiments were performed to study the mechanism of this transformation.
