Halogen-bonded iodonium ion catalysis: a route to α-hydroxy ketones via domino oxidations of secondary alcohols and aliphatic C–H bonds with high selectivity and control
been developed from benzylic secondary alcohols employing catalytic iodonium ions stabilized by DMSO. The reaction proceeds through an unprecedented sequential oxidation of alcohols to ketone and its α-hydroxylation in a controlled manner. The spectroscopic evidences establish the possibility of formation of a stable halogen–bonded adduct between DMSO and iodonium ions.
An efficient method for the direct preparation of high synthetic valuable a-hydroxycarbonyls is described. The simple and readily available I-2 or NBS was used as catalyst. DMSO acts as the oxidant, oxygen source, and solvent. A diverse range of tertiary Csp(3)-H bonds as well as more challenging secondary Csp(3)-H bonds could be hydroxylated in this transformation. The reaction is mild, less toxic and easy to perform.
<i>N</i>,<i>N</i>-Dimethylformamide (DMF) as a Source of Oxygen To Access α-Hydroxy Arones via the α-Hydroxylation of Arones
作者:Weibing Liu、Cui Chen、Peng Zhou
DOI:10.1021/acs.joc.6b02751
日期:2017.2.17
An unprecedented alpha-hydroxylation strategy was developed for the synthesis of alpha-hydroxy arones using N,N-dimethylformamide (DMF) as an oxygen source. Control experiments demonstrated that the oxygen atom of the hydroxy group in the alpha-hydroxy arones produced in this reaction was derived from DMF. This new reaction therefore not only provides an alternative strategy for the a-hydroxylation of arones but also highlights the possibility of using the inexpensive common solvent DMF as a source of oxygen in organic synthesis.