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The direct and photosensitized photolysis of six methylated-1-pyrazolines is described. Examination of the products suggests that direct photolysis leads to ari excited singlet trimethylene, whereas a triplet is produced on benzophenone photosensitization. The trimethylene produced from 4 and 5 is related to the intermediates produced on addition of triplet methylenes to cis-and trans-2-butene. Evidence is presented to support the claim that no intermediate is involved in the addition of singlet methylene to cisand tratu-2-butene.

Oxindoles formerly regarded as +Indoxyls. 3475767. Oxindoles formerly regarded as #-Indoxyls.By R. F. MOORE and S. G . P. PLANT.cycloPentanespirooxindole, cyclohexanespirooxindole, and several derivatives of the latter have been synthesised from the appropriate phenylhydrazides of cyclopentane-or cyclohexane-carboxylic acid. Some of these products had hitherto been regarded as +indoxyls. The position of the substituent in the nitration product of cyclohexanespirooxindole has been established, and the course of the Friedel-Crafts reaction in the 3 : 3-disubstituted oxindole group has been investigated. Perkin and Plant (J., 1923, 123, 676) that 9-acylhexahydro-10 : 11dihydroxycarbazoles (I; R = acyl), from the action of nitric acid on the corresponding acyltetrahydrocarbazoles (I1 ; R = acyl) in acetic acid, undergo a pinacolinic change on being heated alone or in acetic anhydride to give compounds which can readily be deacylated. Of the two alternative structures for the product, C,,H,,ON, the +doxy1 formulation (111) seemed the more probable at the time, and this was later supported by observations which are referred to below. It has more recently been shown by Plant and Robinson (Nature, 1950, 165, 36) that this view is untenable and that the substance must be cyclopentanespirooxindole (IV). Witkop ( J . Amer. Chem. SOC., 1950, 72, 614) independently reached the same conclusion, and Patrick and Witkop (ibid., p. 633) indirectly confirmed the oxindole formulation by showing that nitration of the material obtained by condensing 1-methyloxindole with tetramethylene dibromide gave a compound (V; R = Me) identical with the substance prepared by Perkin IT was observed by

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