Simple, Copper(I)-Catalyzed Oxidation of Benzylic/Allylic Alcohols to Carbonyl Compounds: Synthesis of Functionalized Cinnamates in One Pot

Abstract

An environmentally benign [Cu(I)]-catalyzed oxidation of activated (benzylic/allylic) alcohols to the corresponding carbonyl compounds is presented. Interestingly, the reaction was also compatible with benzylic alcohols containing ortho-bromo substituents on the aromatic ring without competing with the expected intermolecular Buchwald coupling. Significantly, the catalytic system enables the synthesis of cinnamate-esters in a sequential domino one-pot fashion via oxidation followed by Wittig–Horner protocol.

GRAPHICAL ABSTRACT

Keywords:

• Allylic alcohols
• benzylic alcohols
• carbonyl compounds
• cinnamates
• [Cu]-catalysis
• oxidation

Notes

^a Isolated yield of chromatographically pure product.

^b Reaction was not clean.

^c Conversion of the reaction based on TLC.

^d Reaction was carried out under an inert atmosphere.

^e Reaction was performed under open-air conditions fitted with a condenser.

^a All reactions were performed on 0.5-mmol scale of the starting material 1.

^b Isolated yields of chromatographically pure products.

^c Yields are based on the recovery of the starting material.

^d Reactions were carried out on 1-g scale under open-air conditions; accordingly it took more time than that required for small scale.

^e No reaction took place; only starting material recovered (80%). The first and second numbers in parentheses are isolated yields by the methods A and B, respectively.

^a All reactions were performed on 0.5-mmol scale of the starting material 1.

^b Isolated yields of chromatographically pure products 3.