18] Ribonucleoside cyclic phosphates

Abstract

Publisher Summary This chapter discusses ribonucleoside cyclic phosphates and their methods of preparation. Ribonucleoside cyclic phosphates refer to the 2', 3'-monophosphate esters of nucleosides. They are originally isolated as intermediates during the enzymatic or mild alkaline degradations of ribonucleic acids, and independently and simultaneously, synthesized chemically from the 2'- or 3'-nucleoside monophosphates by elimination of a water molecule, where R is a purine or pyrimidine. The ribonucleoside 2', 3'-phosphates contain a 5-membered cyclic phosphate ring and the ribonucleoside 3', 5'- cyclic phosphates contain a 6-membered cyclic phosphate ring. Methods for the preparation of the 3', 5'-cyclic phosphates and ribonucleoside 2', 3'-cyclic phosphates are described. First method is based on dehydration of the monophosphates with dicyclohexylcarbodiimide (DCC) in anhydrous medium. Second method is also based on dehydration with DCC and the procedure for adenosine 2', 3'-cyclic phosphate. Third procedure, originally proposed by Michelson, is based on the use of ethyl chloroformate in anhydrous or aqueous media, an excess of tri-n-butylamine being employed to neutralize the hydrochloric acid released during the course of the reaction. The principal properties of the ribonucleoside cyclic phosphates are also described.