Substrate Directed Regioselective Monobromination of Aralkyl Ketones Using N-Bromosuccinimide Catalysed by Active Aluminium Oxide: α-Bromination versus Ring Bromination

Table 7

Nuclear bromination of various aralkyl ketones containing high activating groups^a.

Entry	Substrate		Product	Time/min	Yield^b/%
	R	R′′
1	H	OH; 1p	4a	12	94
2	OH; 1q	H	4b	11	68
3	NH2; 1r	H	4c	18	72
4	H	NH2; 1s	4d	13	94
5	H	OMe; 1k	4e	15	91
^c6	H	OH; 1p	5a	20	99
^c7	NH2; 1r	H	5b	19	98

aReaction conditions: aralkyl ketone(s) 1p–r (10 mmol), N-bromosuccinimide (12 mmol), and 10% (w/w) neutral Al₂O₃ in acetonitrile (20 mL) at reflux temperature.
^bIsolated yield.
^c22 mmol of NBS was utilized.