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. Author manuscript; available in PMC: 2014 Aug 5.
Published in final edited form as: Chem Asian J. 2011 Jul 7;6(8):2101–2106. doi: 10.1002/asia.201100190

Table 5.

Survey of allenoates 1 for [4+2] annulations with benzylidenecyanoacetate 2n.[a]

graphic file with name nihms610063u6.jpg
Entry R Product Yield [%][b] cis/trans[c]
1 Ph (1b) 3w 81 88:12
2 4-ClC6H4 (1c) 3x 74 89:11
3 CO2Et (1d) 3y 78 77:23
[a]

Reaction conditions: A solution of the allenoate 1 (1.4–3.0 mmol) in benzene (10 mL) was added to a solution of the olefin 2n (1 mmol) and HMPT (20 mol%) in benzene (5 mL) under reflux over 4 h and then the mixture was further heated under reflux.

[b]

Yield of isolated product.

[c]

Determined through analysis of the 1H NMR spectrum of the crude reaction mixture and by comparison with the spectrum of cis-ethyl 5,5-dicyano-4,6-diphenylcyclohex-1-enecarboxylate (for which a single-crystal X-ray structure was obtained). See Ref. [8].