Xanthine, mesoionic

Xanthates, with azothiazoles, 111 Xanthine, mesoionic, 55, 60 Xanthydrol, 117... 

EthylaminothiazoIe when heated to 160 C with the bis(2,4,6-tri-chlorophenyl)malonate esters (120) gives the mesoionic xanthine (121) in good yield (Scheme 80) (130. 282). 

Liquid carbon suboxide added to a solution of 2-ethylaminothiarole in anhydrous ether at 0°C gives immediate formation of a white precipitate of the mesoionic xanthine (121) (R=H) (130), otherwise prepared by reaction between 2-ethylaminothiazole and phenoxycarbonyl isocyanate (see p. 65 and Ref. 304),... 

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