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

Table 2

Effect of solvent on α-bromination of acetophenone^a.

Entry	Solvent	Time/min	Product	Yield^b/%
1	MeOH	10	2a	89
2	EtOH	40	2a	74
3	H2O	24 hrs	2a	15
4	CH3CN	60	2a	51
^c5	^dEther	30	2a	56
6	^dTHF	65	2a	44
7	CH2Cl2	180	2a	55
8	CHCl3	120	2a	48

aReaction conditions: acetophenone 1a (10 mmol), N-bromosuccinimide (12 mmol), 10% (w/w) acidic Al₂O₃, and solvent (20 vol) at reflux temperature.
^bIsolated yield.
^cReaction was conducted at 32°C.
^dFreshly distilled ether and THF were used (peroxide free).