IMIDAZO[1,2-A]PYRIMIDINE 2'-DEOXYRIBONUCLEOSIDE AND 2',3'-DIDEOXYRIBONUCLEOSIDE - GLYCOSYLATION OF THE NUCLEOBASE ANION

The synthesis of the imidazo[1,2-a]pyrimidine 2'-deoxyribonucleosides 2a and 3a related to 2'-deoxyguanosine or 2'deoxyinosine is described. Glycosylation of the nucleobase anion of 5 with 2'-deoxy-3,5-bis-O-(4-methylbenzoyl)-alpha-D-erythro-pentofuranosyl chloride (6) yielded stereoselectively the N-1 beta-D-deoxyribofuranoside 7. Under the same conditions the 2',3'-dideoxyrihalogenoses 11 and 14 were employed to afford anomeric mixtures of glycosylation products (12, 13 and 15, 16). The glycosylation products obtained from the 2'-(deoxyribo- and 2',3'-dideoxyribo halides were then converted into the final nucleosides (2a,b and 3a,b). The inhibitory activity of the imidazo[1,2-a]pyrimidine 2',3'-dideoxynucleoside 5'-triphosphates 28a and 28b against HIV reverse transcriptase was tested.