Selective and Efficient Oxidation of Benzylic Alcohols to Benzaldehydes and Methyl Benzoates by Dibromo-5,5-dimethylhydantoin

Abstract

A selective and efficient method of oxidizing benzyl alcohols to benzaldehydes and methyl benzoates by using 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as oxidant is developed. One-step conversion of benzyl alcohols to methyl benzoates in methanol at room temperature for 12 hours is achieved without any catalysts. Moreover, para-substituted benzyl alcohols are obtained in 86–98% yield. When dichloromethane is used as solvent, further oxidation of benzaldehydes to esters is well controlled, selectively affording benzaldehydes in 89–99% yield within 30 minutes.

[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.]

GRAPHICAL ABSTRACT

Keywords:

• Benzaldehyde
• chemoselective
• dibromo-5,5-dimethylhydantoin
• methyl benzoate
• oxidation

Notes

^a All reactions were run with benzyl alcohol using DBDMH in methanol.

^b GC yield.

^a Substrate (5mmol), methanol (30ml), and DBDMH (20mmol) were stirred at room temperature for 12h.

^b GC yield.

^c Reflux.

^a Substrate (1mmol), dichloromethane (20ml), and DBDMH (1mmol) were stirred at room temperature for 0.5h.

^b GC yield.

^a All reactions were run with benzyl alcohol using DBDMH.

^b GC yield.

^c Not detected by GC.