The first enantioselective chiral phosphoricacid-catalyzedtransferhydrogenation of unprotected ortho-hydroxyaryl alkyl N−H ketimines using Hantszch di-tert-butyl ester as a reductant is reported. A variety of ortho-hydroxybenzylamines were obtained in good to excellent yields and enantiomeric excesses.
Irradiation of o-alkenylphenols with alkylamines resulted in Markovnikov-type amination to give o-(1-alkylaminoalkyl)phenols in relatively good yields. The photoamination was initiated by a proton transfer from the ammonium ion to the alkenyl group of o-alkenylphenolate anion in the excited state in the ion pair formed between the phenols and the amines. The resulting zwitter ion allowed the nucleophilic addition of the amine at the benzylic cation center.
Ruthenium‐Catalyzed Direct Asymmetric Reductive Amination of Diaryl and Sterically Hindered Ketones with Ammonium Salts and H
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作者:Le' an Hu、Yao Zhang、Qing‐Wen Zhang、Qin Yin、Xumu Zhang
DOI:10.1002/anie.201915459
日期:2020.3.23
A Ru-catalyzed directasymmetric reductive amination of ortho-OH-substituted diaryl and sterically hindered ketones with ammonium salts is reported. This method represents a straightforward route toward the synthesis of synthetically useful chiral primary diarylmethylamines and sterically hindered benzylamines (up to 97 % yield, 93->99 % ee). Elaborations of the chiral amine products into bioactive