Table 2.

Preparation of benzisoxazolo[2,3-a]pyridinium tetrafluoroborates (1)^a

Entry	Acetanilide (4)	Product (1)	% Yieldb
1	4a	1a	72
2	4b	1b	77
3	4c	1c	83
4	4d	1d	79
5	4e	1e	80
6	4f	1f	71
7	4g	1g	76
8	4h	1h	74

^aHydrolysis: 4 (1.0 mmol), HBF₄ (50% aqueous solution, 1.2 mmol), water (1 mL), were refluxed until hydrolysis was complete. Diazotization/cyclization: the preceding mixture was evaporated in vacuo and dissolved in CH₃CN (8 mL). ^tBuONO (1.2 mmol) was added. Mixture was stirred 1 hr at RT, then heated to reflux.

^bIsolated yields; average of at least 2 runs.