STUDY OF CYCLOADDITIONS OF MOORES KETENE WITH VINYLARENES

Reactions of Moore's ketene (t-butylcyanoketene. TBCK) with 1- and 2-v inyl-naphthalene, p-phenylstyrene and 9-vinylanthracene are presented. The H-1-NMR and C-13-NMR spectra proved the formation in all cases of a sole reaction product, a cyclobutanone. In the cases of vinylnaphth alenes and p-phenylstyrene the reaction is regio- and stereospecific w ith the formation of the contra-thermodynamic cyclobutanone (with the aryl and t-butyl groups vicinal and cis) as a consequence of a (2) pi( s) + (2) pi(a) concerted reaction mode. 9-vinyl-anthracene reacted reg io-and stereospecifically; the cyclobutanone has the two bulky groups vicinal but trans. The isomer thermodynamically favoured is resulting in a stepwise process as a consequence of the steric influence of the alkene bulky substituent and of its aptitude to stabilise a positive c harge.