Oxetanes startg

A soln. of the startg. keto ester in CCI4 irradiated 4 hrs. with the uranium glass-filtered light of a Hg-lamp -> oxetane deriv. (Y 83%) treated with a silica-gel in hexane -> product (Y 90%). D. Bidian and M. Winnik, Tetrah. Let. 1974, 3857 cf. Synth. Meth. 29, 978 carbonyl-olefin interdiange via oxetane ring cf. G. Jones, II, M. A. Acquadro, and M. A. Carmody, Chem. Commun. 1975, 206. 

A 10-20%-soln. of the startg. m. (mixture of cis- and rrawj-isomers) in diphenyl-methane heated at 280-300° in a Pyrex ampoule methyl 3-methyl-2-butenoate. Y 90%.-In combination with photochemical oxetane ring synthesis from ethylene derivs. and oxo compds. (s. Synth. Meth. 19, 764), ethylene deriv.-oxo compd. interconversion may be achieved. F. e. s. G. Jones II, S. B. Schwartz, and M. T. Marton, Chem. Commun. 1973, 374. 

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