Abstract: .alpha. and .beta.-ribonucleosides of substituted pyrimido[5,4-d]pyrimidines are used in treating malignant tumors in vivo. A novel synthesis for preparing these compounds and other related compounds is further disclosed.

Abstract: 6-Sulfenamide, 6-sulfinamide and 6-sulfonamide purines, purine nucleosides, purine nucleotides and 3 and 7 deaza and 8 aza derivatives thereof of structure: ##STR1## wherein Z is H or --NH.sub.2 ;X is --S--NH.sub.2, ##STR2## T is C--H, G is N and Q is N; or T is C--H, G is N and Q is C--H; orT is N, G is N and Q is C--H; orT is C--H, G is C--H and Q is N;Y is H or an .alpha.-pentofuranose or .beta.-pentofuranose of the formula: ##STR3## wherein R.sub.1 and R.sub.2 independently are H, OH, --O-acyl or ##STR4## or together R.sub.1 and R.sub.2 are ##STR5## and R.sub.3 and R.sub.4 are H or one of R.sub.3 or R.sub.4 is OH and the other is H; provided that when Y is H, Z is --NH.sub.2 ; and acceptable salt thereof are prepared and are useful as antitumor agents or they are intermediates for compounds which are antitumor agents. The compounds are used to treat an affected warm blooded host by serving as the active ingredients of suitable pharmaceutical compositions.

Abstract: The triazole nucleosides 1-(5'-O-sulfamoyl-.beta.-D-ribofuranosyl)[1,2,4]triazole-3-carboxamide, 1-(5'-O-sulfamoyl-.beta.-D-ribofuranosyl)[1,2,4]triazole-3-thiocarboxamide and 1-(5'-O-sulfamoyl-.beta.-D-ribofuranosyl)[1,2,4]triazole-3-carbonitrile ar e prepared and used as antiparasitic agents.

Abstract: A novel class of alkyl-1-(.beta.-D-ribofuranosyl)[1,2,4]triazole-3-carboximidates of the formula: ##STR1## wherein R.sub.1 is methyl or ethyl and R.sub.2 is .beta.-D-ribofuranosyl, are useful as anti-leukemic agents.

Abstract: The compound 8-Chloroadenosine 3',5'-cyclic phosphate is used to treat malignant tumors in warm blooded animals. Two novel single step syntheses of 8-chloroadenosine 3',5'-cyclic phosphate and other related adenine and adenosine compounds from corresponding adenosine 3', 5'-cyclic phosphate and other respective related adenosine compounds are disclosed.