Patent ID: 7560550

Claim:
A method for the production of compounds of the formula (1) where R 1 is a hydroxyl protective group and R 8 , R 9 , R 10 , R 11 are, independently of one another, hydrogen or an amino protective group; by reacting a compound of the formula (2) where X is a leaving group, with a 2,6-diaminopurine derivative of the formula (5) where R 12 is a silyl radical —SiR 4 R 5 R 6 where R 4 , R 5 , and R 6 are each independently an aliphatic or aromatic radical containing up to 20 carbon atoms, in the presence of a Lewis acid, wherein a 1,3-dicarbonyl compound or an —SiR 4 R 5 R 6 silylated derivative of a 1,3-dicarbonyl compound is present during at least a portion of the reaction, and wherein the 1,3-dicarbonyl compound has the following formula: where Y and Z are, independently of one another, hydrogen, an alkyl radical having from 1 to 20 C atoms, an aryl radical having from 6 to 20 C atoms or an alkyloxy group having from 1 to 20 C atoms and R 2 and R 3 , are, independently of one another, hydrogen, an acyl radical of an aromatic or aliphatic carboxylic acid having from 2 to 20 C atoms, an alkyl radical having from 1 to 20 C atoms or an aryl radical having from 6 to 20 C atoms, and at least one of R 2 and R 3 H.