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. 2016 Jun 16;7(10):6369–6380. doi: 10.1039/c6sc01289b

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.