3.4- Dimethyl-benzenesulfonic acid methyl ester

Methylation of 7-amino-l,2,3-triazolo[4,5-d]pyrimidine (8-azaadenine) (140) with dimethyl sulfate afforded the N-3 and N-9 methylated isomers 141 and 142, respectively, which upon further methylation with methyl iodide or benzenesulfonic acid methyl ester gave 3,7- and l,9-dimethyl-8-azaadeninium salts 144 and 145, respectively. Thermal decomposition of the dimethyl derivatives led to a transmethylation to give 6-methylamino-9-methyl-8-azapurine (143), whose methylation afforded 1- and 7-methyl-6-methylamino-9-methyl-8-azapurinium salts 146 and 147 (80ZOR2204) (Scheme 28). 

SOOsP2C4,H44, Osmium, carbonyl(5-thioxo-1,3-pentadiene-1,5-diyl-C, C, 5)bis(tri-phenylphosphine)-, 26 188 SO2C7H, Benzenesulfonic acid, 4-methyl-, rhodium complex, 27 292 S04PC,H,2. 2-Butenedioic acid, 2-(dimeth-ylphosphinothioyl)-, dimethyl ester, manganese complex, 26 163 SO C H , Thiophenetetracarboxylic add. tctramethyl ester, 26 166... 

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