9-Diazoxanthene

To 1,1-dimethoxyethene (2.85 g, 32.4 mmol) in refluxing Nj-purged benzene (100 mL) was slowly added 9-diazoxanthene (1.0 g, 4.8 mmol) in Nj-purgcd benzene (75 mL). After 1.5 h the solvent was removed in vacuo and hexane added to dissolve all but 9-xanthone azine (139 mg, 16%). The hexane-soluble material was chromatographed on silica gel and eluted with Skellysolve B containing increasing amounts of benzene. The chromatographic fractions consisted of crude esters (107 mg), 9-xanthone (200 mg, 25%), unidentified products (103 mg), and the cyclopropane yield 430 mg (40%) mp 130-131 C (Skellysolve B). 

Xanthenyliumsodium (from sodamide and xanthene) reacts with aziridines to give a mixture of 9-mono- (271) or 9,9-di-substituted xanthenes (272).Addition of perchloric acid to unsymmetric allenes such as the 9-xanthylidene derivative (273) (prepared by a new route from 9,9-dichloroxanthene and an alkene) gave a red xanthylium salt (274), which was converted into a colourless spiro-indene (275) on heating.Full details have now been published of the properties and of the reactions of 9-diazoxanthene (276) and 9-xanthylidene (278) with methyl acrylate, substituted styrenes, several ketones, and alkyl-benzenes. The kinetics of the reaction with styrenes were studied and the conversion of (276) into (278) was achieved by photolysis of the tosylhydrazone (277) at —25 °C. 

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