Regioselective α-Bromination of Aralkyl Ketones Using N-Bromosuccinimide in the Presence of Montmorillonite K-10 Clay: A Simple and Efficient Method

Abstract

A simple and more convenient method has been developed for regioselective α-bromination of various aralkyl ketones with N-bromosuccinimide (NBS) in the presence of Montmorillonite K-10 catalyst in methanol at 60–65 °C. The present procedure offers advantages of short reaction time, simple workup, good yields of products and reusability of the catalyst for four times without loss of activity.

Supplemental materials are available for this article. Go to the publisher's online edition of Synthetic Communications® to view the free supplemental file.

GRAPHICAL ABSTRACT

Keywords:

• Aralkyl ketones
• α-bromination
• Montmorillonite K-10 clay
• N-bromosuccinimide
• regioselectivity

ACKNOWLEDGMENTS

We are thankful to the Council of Scientific and Industrial Research (CSIR), New Delhi, India, for financial support for this work under a major research project (No. 01 (2391)/10/EMR-II).

Notes

^a Reaction conditions: Acetophenone (10 mmol), NBS [10 (+2) mmol: portionwise addition], 10% Montmorillonite K-10, and methanol (20 ml).

^b Scheme 2.

^a Reaction conditions: Acetophenone (10 mmol), NBS (11 (+2) mmol: portionwise addition), 10% Montmorillonite K-10, methanol (20 ml), and temperature 30–35 °C.

^b Isolated yield.

^c Isolated yields were shown in parentheses, when the reactions were carried out under reflux temperature.

^a Reaction conditions: Acetophenone (10 mmol), NBS [10 (+2) mmol: portionwise addition], 10% Montmorillonite K-10, and methanol (20 ml).

^b Isolated yield.

^a Reaction conditions: Acetophenone (10 mmol), NBS [10 (+2) mmol)], 10% Montmorillonite K-10, and methanol (20 ml) at 65 °C.

^b Isolated yield.

^a Reaction conditions: Substrate (10 mmol), NBS 10 (+2) mmol added in either one or six portions, 10% Montmorillonite K-10 catalyst, methanol (20 ml), and temperature 60–65 °C.