FLUORESCENT NUCLEOSIDE ANALOGUES. SYNTHESIS OF FLUORESCENT PYRIDOPURINES, AND THEIR CORRESPONDING RIBOSIDES

Article abstract of DOI:10.1016/S0040-4020(01)96552-4

Fluorescent pyrido<2,1-i>purines can in principle be obtained via Michael-addition of a suitable anion of a purine derivative to an acetylenic ester, followed by based-catalyzed cyclization, as depicted in Scheme II. 6-Substituted purine-derivatives are obtained via nucleophilic substitution on 6-chloro- and 6-methylsulfonylpurine (8a and 8b).In the presence of methyl propiolate and sodium methoxide, before cyclization, two consecutive Michael-additions take place, leading to 13 and 14.With substituted acetylenic esters, cyclization occurs after one Michael-addition. Michael-additions with ethylenic esters did not lead to expected cyclization products, except in cases where oxidation took place.For the conversion of the pyrido<2,1-i>purines into the corresponding ribosides protection against nucleophilic attack was necessary.