Xanthylium perchlorate

Diazomethanc undergoes addition of xanthylium perchlorate to afford dibenz[6,/]oxepin (4).193 The formation of this product can be rationalized by a carbenium ion that undergoes a Wagner Meerwein rearrangement. 

Xanthylium perchlorate has been oxidized to xanthone by manganese dioxide (68AC(R)251>. 

A suspension of thio-xanthylium perchlorate in ether treated with excess methylmagne-sium iodide in ether 9-methy Ithioxanthene. Y 80%. 

Disubstituted pyrylium salts, such as (41), are attacked at C-4 only (74JOU2015) and in the presence of perchloric acid a new pyrylium salt (42) is formed. Flavylium (43) and xanthylium (44) salts also react at the y-position, for instance, with CH-acidic reagents such as pentane-2,4-dione, malonic acid derivatives or aromatic electron-rich compounds like IV V-dimethylaniline, 1,3-dimethoxybenzene or IV-methylindole (59CB46, 74CHE1019) some examples are shown in Scheme 1. 2,4-Disubstituted pyrylium cations, e.g. (45), react at C-6 (80JOC5160). 

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. 

CA Index Name Xanthylium, 3,6-bis(dimethylamino)-9-[2-(methoxycarbonyl)phenyl]-, perchlorate... 

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