Abstract: In one embodiment, the present invention relates to a new class of ammonium salts of N?-acyl derivatives of N?-(4-amino-4-deoxypteroyl)-L-ornithine compounds having a structure according to formula II-IV. Formula II has the structure of: wherein: R2 represents up to four groups independently selected at each occurrence of R2 from the group consisting of hydrogen, C1-6 alkyl, C2-6 alkenyl, C2-6 alkynyl, C3-8 cycloalkyl, C1-6 alkoxy, chloro, fluoro, hydroxy, and —COOH; R3, R4, and R5 are each independently selected from hydrogen and C1-6 alkyl; or NR3R4 taken combination can form a 5 to 7 member heterocycle having at least one nitrogen ring atom; and x is a real number greater than 0 and less than about 4. The ammonium salts provided by the invention exhibit high inhibitory activity against the growth o methotrexate-resistant cells, and also exhibit superior chemical stability than corresponding acidic N?-acyl derivatives of N?-acyl derivatives of N?(4-amino-4-deoxypteroyl)-L-ornithine compounds.

Abstract: The invention includes methods for isolating crystalline Form I of 5-azacytidine substantially free of other forms, wherein 5-azacytidine is represented by the formula: The invention also includes pharmaceutical compositions comprising Form I of 5-azacytidine.

Abstract: The disclosure includes novel polymorphic and pseudopolymorphic crystalline forms of 5-azacytidine, along with methods for preparing said forms, wherein 5-azacytidine is represented by the formula: The disclosure also includes pharmaceutical compositions comprising said forms.

Abstract: The invention provides novel polymorphic and pseudopolymorphic crystalline forms of 5-azacytidine, along with methods for preparing said forms, wherein 5-azacytidine is represented by the formula: The invention also includes pharmaceutical compositions comprising said forms.

Abstract: A process for substantially enhancing the regio and stereoselective synthesis of 9-?-anomeric nucleoside analogs is described. The introduction of the sugar moiety onto a 6-substituted purine base was preformed so that only the 9-?-D- or L-purine nucleoside analogs were obtained. This regio and stereoselective introduction of the sugar moiety allows the synthesis of nucleoside analogs and in particular 2?-deoxy, 3?-deoxy, 2?-deoxy-2?-?-fluoro and 2?,3?-dideoxy-2?-?-fluoro purine nucleoside analogs in high yield without virtually any formation of the 7-positional isomers. The compounds are drugs or intermediates to drugs.

Abstract: A process for substantially enhancing the regio and stereoselective synthesis of 9-&bgr;-anomeric nucleoside analogs is described. The introduction of the sugar moiety onto a 6-substituted purine base was preformed so that only the 9-&bgr;-D- or L-purine nucleoside analogs were obtained. This regio and stereoselective introduction of the sugar moiety allows the synthesis of nucleoside analogs and in particular 2′-deoxy, 3′-deoxy, 2′-deoxy-2′-&bgr;-fluoro and 2′,3′-dideoxy-2′-&bgr;-fluoro purine nucleoside analogs in high yield without virtually any formation of the 7-positional isomers. The compounds are drugs or intermediates to drugs.

Abstract: A process for the preparation of 2-fluoro-9- (2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl)adenine (I) is described. The process involves reacting a protected 2-fluoro adenine with a protected chlorosugar under controlled conditions of temperature (80-85.degree. C.) to produce (I), rather than using a process involving fluorinating a 2-substituted nucleoside precursor of (I).

Abstract: A process for the preparation of 2-fluoro-9-beta-D-arabinofuranosyl purine (VII) by a reaction of palladium chloride and hydrochloric acid with 2-fluoro-9-(2,3,5-tribenzyl-beta-D-arabinofuranosyl)adenine (VI) at elevated pressures in a solvent for (VI) is described. The reaction is rapid, economical and efficient.

Abstract: A process for the preparation of 2-amino-9-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl) adenine (V) is described. The process uses a protected 2,6-di(tri-alkylsilylamino)-9-trialkylsilylpurine (II) which is reacted with protected chlorosugar 2,3,5-tri-O-benzyl-1-chloro-D-arabinofuranose (III) and then the protection groups are removed from the 2 and 6 positions. The process provides a 9-beta-D-arabinofuranosyl-2-fluoroadenine (VII) which is an antileukenine drug.

Abstract: A process for the preparation of 2,6-diamino-9-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl)purine (V) by reacting 2,6-di(alkoxyacetamido)purine (II) with 2,3,5-tri-O-benzyl-1-chloro-alpha-D-arabinofuranose (III) to produce 2,6-di(alkoxyacetamido)-9-(2,3,5-tri-O-benzyl-beta-D-arabinofuranosyl)puri ne (IV) and then deprotecting the 2,6-positions to produce the 2,6-diamine (V) is described. The process provides purine (V) in high yield. Purine (V) is an intermediate in the preparation of 9-beta-D-arabinofuranosyl-2-fluoroadenine which is a cytotoxic agent.