Optimization of reaction conditions^a.

S. no.	Pd(OAc)2	PTSA (equiv.)	Yieldsb (%)
1	10 mol%	0.75	60
2	10 mol%	1.0	56
3	10 mol%	0.25	69
4	15 mol%	0.25	46
5	7.5 mol%	0.25	69
6	5 mol%	0.25	74
7	3 mol%	0.25	70
8	5 mol%	0.25	64c
9	5 mol%	0.25	70d
10	5 mol%	0.25	61e
11	5 mol%	0.25	62f
12	5 mol%	0.25	84 g
13	5 mol%	0.25	65h
14	5 mol%	0.25	70i

^aReagents and conditions: a mixture of 3-phenyl-2H-benzo[b][1,4]oxazin-2-one (1a, 1 equiv.), NBS (2a, 1.2 equiv.), Pd(OAc)₂ and PTSA as indicated in the parenthesis were irradiated with microwave under indicated solvent at indicated temperature for given period of time in sealed reaction vial.

^bIsolated yields.

^cReaction mixture was irradiated at 110 °C for 15 minutes.

^dReaction mixture was irradiated at 90 °C for 30 minutes.

^eReaction was irradiated at 80 °C for 30 minutes.

^fReaction was irradiated at 100 °C for 25 minutes.

^gReaction was irradiated at 100 °C for 15 minutes.

^hReaction was irradiated at 100 °C for 10 minutes.

ⁱReaction was carried out at 100 °C under conventional heating for 1 hour.