Alkoxybromination of Olefins Using Ammonium Bromide and Oxone

Abstract

A mild, efficient, and highly regio- and stereoselective method for the methoxy and ethoxy bromination of olefins has been developed using NH₄Br as a bromine source and Oxone as an oxidant. Various kinds of olefins (aromatic, linear, and cyclic olefins) afforded the corresponding alkoxy brominated products in moderate to excellent yields.

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

GRAPHICAL ABSTRACT

Keywords:

• Alkenes
• alkoxybromination
• Oxone
• regioselectivity
• vicinal functionalization

ACKNOWLEDGMENT

M. A. K. and M. N. acknowledge the financial support from the Council of Scientific and Industrial Research, India, in the form of fellowships.

Notes

^a Styrene (2 mmol), NH₄Br (2.2 mmol), Oxone (2.2 mmol), ROH (10 mL).

^b Isolated yields.

^c At room temperature.

^d At 80 °C.

^a Isolated yields.

^b Olefin (2 mmol), NH₄Br (2.2 mmol), Oxone (2.2 mmol), MeOH (10 mL) at room temperature.

^c Olefin (2 mmol), NH₄Br (2.2 mmol), Oxone (2.2 mmol), EtOH (10 mL) at reflux temperature.

^d At room temperature.

^e Dibromo product.

^f erythro products.

^g threo products.

^h Molar ratio of erythro and threo 62:38, determined by ¹H NMR.

ⁱ Molar ratio of threo and erythro 33:67, determined by ¹H NMR.

^a Isolated yields.

^b Olefin (2 mmol), NH₄Br (2.2 mmol), Oxone (2.2 mmol), MeOH (10 mL) at room temperature.

^c Olefin (2 mmol), NH₄Br (2.2 mmol), Oxone (2.2 mmol), EtOH (10 mL) at reflux temperature.

^d At room temperature.

^e Dibromo product.