Ketene. Part 24. The reactions of N-(fluoren-9-ylidene)methylamine N-Oxide with dimethvlketene and ketene

On the reaction of diphenylketene with isocyanides

“…pathway was shown to involve an isocyanide/ketene interaction resulting in compound 9 and its hydrolysis product. 10 The mechanism of these formal [2 + 2 + 1] cycloadditions has not been fully established but, in the isocyanide case, the presumed intermediacy of zwitterion 1, formally an iminesubstituted oxyallyl, suggested to us the possibility of engineering conditions in which this adduct might be trapped with 1,3dienes to result in a-iminocycloheptenones (10, Scheme 2), a reaction that might have some utility in synthesis, particularly if the diene could be tethered in some way to the zwitterion. 11 Whilst this proposal proved fanciful, 12 during the course of this study we discovered a new pathway in the ketene/isocyanide manifold and, as a bonus, were able to obtain the first X-ray crystallographic confirmation of the structures of compounds of general structure 3.…”

Ketene. Part 25. Mechanistic studies of the reaction of nitrile oxides with ketenes

“…The reactions of ketenes with nitrones lead to a wide range of products. Where the reaction involves C,C-biphenylene nitrones (1) and related compounds, oxazolidinones (2) are commonly formed ' v 3 along with other compounds. Several, wholly conjectural mechanisms have been proposed for this transformation 2*4 but no experimental evidence had so far been published which helps to explain the formation of the adducts (2).…”