Abstract: Provided are compounds of the following formulae:A phosphonomethoxymethyoxymethyl purine/pyrimidine derivative of the formula ##STR1## wherein X and X' are the same or different and are hydrogen or alkyl. R and R' are the same or different and are hydrogen, alkyl, hydroyalkyl or alkanoyl andB is a purine or pyrimidine base.

Abstract: Provided are compounds of the following formulae:A phosphonomethoxymethyoxymethyl purine/pyridimidine derivative of the formula ##STR1## wherein X and X' are the same or different and are hydrogen or alkyl. R and R' are the same or different and are hydrogen, alkyl, hydroxyalkyl or alkanoyl andB is a purine or pyrimidine base.A compound of formula (II) or (VIII) ##STR2## wherein the broken line is an optional bond; X, R and X' are the same or different and are H or alkyl with 1 to 6 carbon atoms;wherein in the compound of formula (II), Y and Z are the same or different and are H; OH; alkyl having 1 to 6 carbon atoms; alkyl having 1 to 6 carbon atoms which is substituted with halogen, hydroxy, amino or azido; or Y and Z are taken together to form an oxygen atom or a methylene group; or Y is taken together with X' to complete a cyclic phosphonate having the structure of formula (III) ##STR3## wherein R.sup.

Abstract: Provided are compounds of the following formulae:A phosphonomethoxymethyoxymethyl purine/pyrimidine derivative of the formula ##STR1## wherein X and X' are the same or different and are hydrogen or alkyl. R and R' are the same or different and are hydrogen, alkyl, hydroxyalkyl or alkanoyl andB is a purine or pyrimidine base.A 4'-phosphonomethoxytetrahydrofuranyl-1'-purine-pyrimidine of the formula ##STR2## wherein X and X' are the same or different and are hydrogen or alkyl, Y and Z are the same or different and are hydrogen, hydroxyl or alkyl or Y+Z is an alkenyl, an epoxide or cyclopropyl, andB is a purine or pyrimidine base.

Abstract: Provided are compounds of the following formulae:A phosphonomethoxymethyoxymethyl purine/pyrimidine derivative of the formula ##STR1## wherein X and X' are the same or different and are hydrogen or alkyl. R and R' are the same or different and are hydrogen, alkyl, hydroxyalkyl or alkanoyl andB is a purine or pyrimidine base.A 4'-phosphonomethoxytetrahydrofuranyl-1'-purine-pyrimidine of the formula ##STR2## wherein X and X' are the same or different and are hydrogen or alkyl, Y and Z are the same or different and are hydrogen, hydroxyl or alkyl or Y+Z is an alkenyl, an epoxide or cyclopropyl, andB is a purine or pyrimidine base.

Abstract: Provided are compounds of the following formulae:A phosphonomethoxymethyoxymethyl purine/pyrimidine derivative of the formula ##STR1## wherein X and X' are the same or different and are hydrogen or alkyl. R and R' are the same or different and are hydrogen, alkyl, hydroxyalkyl or alkanoyl;B is a purine or pyrimidine base.optionally R is taken together with X' to complete a cyclic phosphonate having the formula ##STR2## A 4'-phosphonomethoxytetrahydrofuranyl-1'-purine-pyrimidine of the formula ##STR3## wherein X and X' are the same or different and are hydrogen or alkyl, the dashed line is an optional bond,Y and Z are the same or different and are hydrogen, hydroxyl or alkyl or Y+Z are taken together to form an epoxide or cyclopropyl, andB is a purine or pyrimidine base.

Abstract: Provided are compounds of the following formulae: A phosphonomethoxymethyoxymethyl purine/pyrimidine derivative of the formula ##STR1## wherein X and X' are the same or different and are hydrogen or alkyl. R and R' are the same or different and are hydrogen, alkyl, hydroxyalkyl or alkanoyl andB is a purine or pyrimidine base.A compound of formula (VI) ##STR2## wherein X is halogen, Y is S-phenyl, Se-phenyl or halogen and B is hypoxanthine, xanthine, guanine, 8-bromoguanine, 8-chloroguanine, 8-methylguanine, 8-thioguanine, 3-deazaguanine, purine, 2-aminopurine, 2,6-diaminopurine, adenine, 3-deazaadenine, 8-aminoguanine, 8-hydrazinoguanine, 8-hydroxyguanine, cytosine, 5-ethylcytosine, 5-methylcytosine, thymine, uracil, 5-chlorouracil, 5-bromouracil, 5-ethyluracil, 5-iodouracil, 5-propyluracil or 5-vinyluracil, 2-acetamido-6-diphenylcarbamoylpurine, 6-N-dimethylamino-methyladenine or 6-N-pivaloyladenine.