Abstract
Selective and efficient α-bromination of β-ketoesters and cyclic and acyclic ketones is achieved by reaction with N-bromosuccinimide (NBS) catalyzed by silica-supported sodium bicarbonate (NaHCO3 · SiO2) under mild reaction conditions and with short reaction times. With 100% selectivity with all substrates, after 45 min at room temperature (20 ± 2 °C), conversions for ethylacetoacetate were 67% and for acetophenone, cyclohexanone, and cycloheptanone were 58, 50, and 55%, respectively. Acetyl acetone recorded 65% conversion with 100% selectivity. Although cyclopentanone and toluene had only 20% conversion, both reactions showed 100% selectivity toward α-bromination. The catalysts exhibit activity and reusability.
GRAPHICAL ABSTRACT
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Notes
Notes. Ethylacetoacetate, 1.0 mmol; NBS, 1.2 mmol; catalyst, 200 mg. Temperature, 20 ± 2 °C.
a Mean of duplicate runs.
Notes. Substrate, 1.0 mmol; NBS, 1.2 mmol, and catalyst, 200 mg. Reaction duration, 45 min. Temperature, 20 ± 2 °C.
a Mean duplicate runs.