Urea nucleosides as therapeutic and diagnostic agents

A compound of the formula:

• wherein:
• X is independently selected from the group consisting of H, aryl, aralkyl, alkyl, alkaryl, alkenyl, alkynyl, alkoxy, —NR102, and —C(O)C(R8)2CH(R8)NR1R2, and wherein at least one of X is —C(O)C(R8)2CH(R8)NR1R2;
• R1 and R2 are independently selected from the group consisting of H, C1-C18 alkyl, alkenyl or alkynyl, phenyl, aralkyl, alkaryl, an alkanoic acid, an ester or amide derivative of an alkanoic acid, a peptide fragment, an HIV aspartyl protease inhibitor, a group that is cleaved intracellularly, and a group that increases the hydrophilicity, hydrophobicity, or hydrogen bonding capacity of the compound;
• R3, R4 and R5 are independently selected from the group consisting of H, —OH, protected oxy-, —NH2, F, —N3, —CN, —NC, —OAc, —SAc, —OBz, and —OSiR73, wherein R7 is C1-C4 alkyl or phenyl;
• R6 is selected from the group consisting of —OH, protected oxy-, phosphate, diphosphate, triphosphate, phosphate esters, phosphoramidites, phosphorothionates, and phosphorodithionates;
• R8 is independently selected from the group consisting of H, aryl, aralkyl, alkyl, alkaryl, alkenyl, alkynyl, alkoxy, and —C(O)—R9, where R9 selected from the group consisting of H, alkyl, aryl, aralkyl, alkaryl and alkoxy;
• R10 is independently selected from the group consisting of H, alkyl, aryl, aralkyl, alkaryl and R9C(O);
• the protected oxy-groups of R4 and R5 taken together can represent an isopropylidene group of the formula (—OC(CH3)2O—) or an orthoformate group of the formula (—OCH(OR7)O—);
• and
• the protected oxy-groups of R5 and R6 taken together can represent a 3′,-5′-tetraalkyldisiloxane group (—OSi(alkyl)2OSi(alkyl)2O—).