Selective reduction of aldehydes and ketones to alcohols with ammonia borane in neat water

Graphical abstract: Selective reduction of aldehydes and ketones to alcohols with ammonia borane in neat water

Chemoselective reduction of various carbonyl compounds to alcohols with ammonia borane (AB), a nontoxic, environmentally benign, and easily handled reagent, in neat water was achieved in quantitative conversions and high isolated yields. Interestingly, α- and β-keto esters were selectively reduced to corresponding hydroxyl esters by AB, while diols were obtained when sodium borohydride was used as a reducing agent. The procedure is also compatible with the presence of a variety of base-labile protecting groups, such as tosyl, acetyl, benzoyl, ester groups, and acid-labile protecting groups such as trityl and TBDMS groups, and others, such as the unsaturated double bond, nitro and cyano groups. Finally, a kilo scale reaction of methyl benzoylformate with AB was conducted in water and gave methyl mandelate in 94% yield.

Selective reduction of aldehydes and ketones to alcohols with ammonia borane in neat water

*Corresponding authors
aKey Laboratory of Green Chemical Media and Reactions, Ministry of Education, College of Chemistry and Environmental Science, Henan Normal University, Xinxiang 453007, China
E-mail: zgs@htu.cn
Tel: +86 373 3325250
Green Chem., 2012,14, 1372-1375

DOI: 10.1039/C2GC00006G

 

http://pubs.rsc.org/en/content/articlelanding/2012/gc/c2gc00006g#!divAbstract

 

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////////Selective reduction, aldehydes and ketones, alcohols,  ammonia borane, neat water

Highly efficient visible-light-driven photoelectro-catalytic selective aerobic oxidation of biomass alcohols to aldehydes

Highly efficient visible-light-driven photoelectro-catalytic selective aerobic oxidation of biomass alcohols to aldehydes

 

 

Green Chem., 2014, Advance Article DOI: 10.1039/C4GC00454J,

http://pubs.rsc.org/en/Content/ArticleLanding/2014/GC/C4GC00454J?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FGC+%28RSC+-+Green+Chem.+latest+articles%29#!divAbstract

Paper Yajun Zhang, Guohua Zhao, Yanan Zhang, Xiaofeng Huang Highly efficient visible-light driven synergistic photoelectrocatalytic aerobic oxidation of biomass alcohols to aldehydes using Au/CeO2-TIO2 NT photocathodes under the mild conditions.

Department of Chemistry, Key Laboratory of Yangtze River Water Environment, Tongji University, Shanghai 200092, People’ s Republic of China
E-mail: g.zhao@mail.tongji.edu.cn;

 

A green and highly efficient visible-light-driven synergistic photoelectrochemical (PEC) catalysis system was systematically demonstrated for selective oxidation of biomass alcohols to the corresponding aldehydes in an O2 atmosphere under the mild conditions by employing the Au/CeO2–TiO2 NTs as photocathodes. Results showed that the conversion of benzyl alcohols was as high as 98% and the selectivity of benzaldehyde was >99% at the bias potential of −0.8 V under the visible light irradiation for 8 h. The superior performance could be attributed to the synergistic PEC process combining both the advantages of photocatalytic and electrocatalytic activity. Furthermore, the research elucidated that the PEC activity and the conversion rate of benzyl alcohol could be effectively promoted by adjusting the potential. Interestingly, the incorporation of CeO2 nanoparticles (NPs) into the inner wall of TiO2 NTs can remarkably enhance the selectivity of the PEC oxidation reaction towards a specific direction. Additionally, the rationally designed and fabricated Au/CeO2–TiO2 NT photocathode was in favour of separating electrons and holes. A probable mechanism for the PEC selective aerobic oxidation process was proposed and discussed.