Table 2. Rearrangement of 8a to 6a: selected optimization.

Entry	Conditions a	Conversion b	Yield c
1	5 equiv. 16, MeOH, 170 °C, 8 h d	46%	13%
2	5 equiv. 16, MeOH, 120 °C (mW), 12 h	N.D.	21%
3	0.4 equiv. 16, MeOH, 120 °C (mW), 8 h	N.D.	32% e
4	0.4 equiv. 16, HFIP, 150 °C (mW), 3 h	45%	47% e , f
5	0.4 equiv. 16, HFIP, 150 °C (mW), 3 h	58%	56% e , f , g

^a[8a] = 0.1 M (0.075 mmol).

^bConversion was calculated based on the recovery of 8a.

^cIsolated yield after column chromatography.

^dThe reaction was carried out in a sealed tube.

^eThe reaction vial was pretreated by N,O-bis(trimethylsilyl)acetamide.

^f[8a] = 0.5 M (1 mmol).

^gThe heating sequence was composed of 12 cycles with each cycle including irradiation at 150 °C for 15 min and at 50 °C for 15 min.