Skip to main content
. Author manuscript; available in PMC: 2010 Aug 6.
Published in final edited form as: Org Lett. 2009 Aug 6;11(15):3430–3433. doi: 10.1021/ol901283m

Table 2.

Thermal [4 + 2] Cycloaddions of of Allenamides.

entry allenamidesa time [h] cycloadducts yield [%]b
graphic file with name nihms133276t1.jpg graphic file with name nihms133276t2.jpg
1 13a: R = p-Ns 12 14a: R = p-Ns 92
2 13b: R = Boc 20 14b: R = Boc 65
3 13c: R = (−)-menthyl 20 14c: R = (−)-menthyl 54c
graphic file with name nihms133276t3.jpg graphic file with name nihms133276t4.jpg
4 (±)-15a: R = Ph 2 16a: R = Ph 77d
5 (±)-15b: R = Me 30 16b: R = Me 57d
6 17 graphic file with name nihms133276t5.jpg <12 graphic file with name nihms133276t6.jpg19 77
7 18 graphic file with name nihms133276t7.jpg 4 graphic file with name nihms133276t8.jpg20 93
8 21 graphic file with name nihms133276t9.jpg 24 graphic file with name nihms133276t10.jpg23 95e
9 24 graphic file with name nihms133276t11.jpg 20 graphic file with name nihms133276t12.jpg25 78
a

Unless otherwise noted, all reactions were carried out in THF at 85 °C at concn = 0.10 M. Reactions in entries 3 and 8 were run in toluene. Entries 4 and 8 were run at 45 °C and 110 °C, respectively.

b

Isolated yields.

c

Only one isomer by 1H NMR but absolute configuration unassigned.

d

16a and 16b were found as a ~ 3:1 inseparable isomeric mixture.

e

Regioisomeric ratio of regioisomers 22 and 23 is ~ 4:1.