Novartis International Pharmaceutical, Ltd.

Andrew Colin Share

Graham R Geen

Thomas Weir Ramsay

Neil Michael Smith

Richard Freer

Intermediates such as methyl 2,2-dimethyl-5-ethenyl-1,3-dioxane-5-carbonate useful to prepare antiviral compounds such as penciclovir and famciclovir are disclosed.

Process for the production of purine derivatives and intermediates therefor

The invention provides a method of rearranging a compound of formula (I), wherein R and R&prime; are selected independently from hydrogen and C alkyl; and R and R are selected independently from hydrogen, hydroxy, halo, C alkyl- or aryl carbonate, amino, mono- or di-C alkylamino, C alkyl or arylamido, C alkyl- or arylcarbonyl, C alkyl- or arylcarboxy, C alkyl- or arylcarbamoyl, C alkyl, C alkenyl, C alkynyl, aryl, heteroaryl, C alkoxy, aryloxy, azido, C alkyl- or arylthio, C alkyl- or arylsulfonyl, C alkyl- or arylsilyl, C alkyl- or arylphosphoryl, and phosphato; to form a compound of formula (II), wherein R, R&prime;, R and R are as defined for formula (I); said method comprising treating the compound of formula (I) with a palladium (0) catalyst and a (diphenylphosphino) C alkane, wherein n is an integer of 1-6. The invention also provides methods of R making penciclovir and famciclovir using this rearrangement reaction.

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Saffron Walden, United Kingdom

Andrew Colin Share