Table 6. Thermal rearrangement of isolated VCP.

Entry	VCP precursor					Temp. (°C)	VCPR product
	#	X	R1	R2	R3		#	Conv. a (%)	Yield b (%)
1	19a	F	Ph	CON(Me)OMe	H	95	35	100	97
2	19b	F	Ph	H	CON(Me)OMe	160		0 c	— d
3	20a	F	Ph	CO2Et	Me	155	36	0 c	— e
4	21a/b f	F	Ph	H/CN	H/CN	90	37	71 g	—
5 h	21b	F	Ph	H	CN	160		100	48 i
6	47	H	Ph	CO2Et	H	220	38	100	40 j
7	19a	F	Piperonyl	CO2Et	H	70	39	42 k	18 l

^a Conversion to product (determined by ¹H or ¹⁹F NMR).

^b Isolated yields unless otherwise stated.

^c Full conversion of VCP precursor was observed.

^d Decomposition was observed.

^e Clean product could not be isolated from crude reaction mixture.

^f 3 : 2 mixture of 21a and 21b, respectively.

^g Crude mixture also contains 26% 21b and 3% cis-42 (determined by ¹⁹F NMR).

^h Using crude reaction mixture from entry 4.

ⁱ 6 : 1 ratio of difluorocyclopentene 37 and alkene isomer 43 (by ¹H NMR).

^j 22% of cis-cyclopentene 38b was also isolated.

^k Crude reaction mixture also contains 58% of [3,3]-product (44, by ¹⁹F NMR).

^l 11% of 44 was also isolated.