Electroreductive cross-coupling between aldehydes and ketones or imines via cathodically generated dianions

Abstract

1,2-Diols are an important class of compounds. Nonetheless, the preparation of unsymmetrical 1,2-diols via the direct cross-coupling of two different carbonyl compounds under simple and mild conditions remains an elusive goal. Herein, an operationally simple electroreductive cross-coupling of two common carbonyls, aldehydes and ketones using electrons as safe reducing agents is reported. By applying this new protocol, a library of unsymmetrical 1,2-diol derivatives were readily accessed. Moreover, this electrochemical protocol also enabled reductive coupling between aldehydes and imines, thereby providing an efficient access to valuable β-amino alcohols. These practical reactions feature a broad substrate scope and high functional group tolerance (more than 60 examples), and it is applicable for large-scale synthesis and late-stage functionalization of complex molecules including natural products and drug derivatives. Mechanistic studies indicate that the reaction might proceed via a nucleophilic attack of electrogenerated dianions from ketones and imines with aldehydes.