A Highly Regioselective and Practical Synthesis of α‐Aryl Ketones under a Cooperative Cascade Effect of an Ionic Liquid and Tetrabutylammonium Fluoride

A metal‐free regioselective synthesis of α‐aryl ketone from corresponding bromohydrin via cooperative cascade effect of [hmim]Br and tetrabutylammonium fluoride under microwave irradiation is reported. Applications of the protocol are illustrated by synthesis of drug intermediates piperonyl‐methyl ketone and 2‐tetralone. Interestingly, direct regioselective transformation of epoxide and 1,2‐diol into α‐aryl ketone under neat [hmim]Br has also been realized. Advantages of this method are demonstrated through the recyclability of [hmim]Br‐tetrabutylammonium fluoride catalytic system and gram scalability. Microwave dinner: A practical and general cooperative cascade effect of an ionic liquid and tetrabutyl ammonium fluoride in the regioselective synthesis of α‐aryl ketones via Wacker‐type oxidation of bromohydrins to ketones is presented.