Yukio Kitade

Reductive cleavage of the ribose moiety in purine nucleosides using diisobutylaluminum hydride: A new method for the preparation of acyclonucleosides

Abstract Reaction of purine nucleosides, such as 2′,3′- O - isopropylideneinosine 1a and 2′,3′- O -isopropylideneadenosine 1c , with diisobutylaluminum hydride in dry tetrahydrofuran resulted in the reductive cleavage of the ribose moiety at the anomeric position to give the corresponding 9-(2′,3′- O -isopropylideneribityl)purines 2a , c in good yields.

Synthesis of a ring-scission analogue of neplanocin A as a potential inhibitor of S-adenosylhomocysteine hydrolase

The ring scission analogue of neplanocin A (1), acycloneplanocin A (2), as a potential S-adenosylhomocysteine hydrolase inhibitor was synthesized via the reductive cleavage of 2′,3′-O-isopropylideneadenosine (3) by DIBALH.

Novel Intramolecular Rearrangement of 5-Carbamoyluracils into Barbituric Acids.

Abstract Heating of 5-carbamoyl- (1) and 5-thiocarbamoyl-3-methyl-1-phenyluracil (5) derivatives in ethanolic sodium ethoxide causes a novel intramolecular rearrangement to give 5-anilinomethylenebarbituric acids(2) and 5-anilinomethylene-4-thiobarbituric and(6), respectively.

Novel reactiom of 5-nitro(or carbamoyl)uracil derivatives with amines. Thermal exchange reaction of N1-portion of the uracils for amines via ring-opening and ring-closure processes☆

Abstract The reaction of 1,3-disubstituted uracils possessing an electron withdrawing group at the 5-position with amines induced exchange of N 1 -portion of the uracil ring for amines. This reaction was accelerated by substitution of phenyl groups at the N 1 -position.

Synthesis of phidolopin, 7-(4-hydroxy-3-nitrobenzyl)-1,3-dimethylxanthine from the bryozoan Phidolopora pacifica

Abstract A total synthesis of a biologically active compound, phidolopin, was accomplished and its regioisomer was also synthesized.

Oxidative Cyclization of 2′,3′-O-Isopropylidene-Adenosines into 5′-O,8-Cycloadenosines with Lead Tetraacetate: Remarkable Effect of N6-Substituents on the Oxidation

Abstract Oxidation of 2′,3′-O-isopropylideneadenosines (1) with lead tetraacetate (LTA) in dry benzene resulted in the formation of the corresponding 5′-O,8-cyclo-2′,3′-O-isopropylideneadenosines (2), which has a new methodological implication for the chemical modification of adenosines. The occurrence of the oxidative cyclization was remarkably affected by the nature of N6-substituents: N6-benzoyl substitution prominently accelerated the oxidative cyclization in comparison with none and dimethyl substitutions. In the oxidation of N6,N6-dimethyladenosine (1d), an intriguing oxidative demethylation was observed.

Photoinduced electron-transfer oxygenation of 7-methyl-9-(β-d-ribofuranosyl)guaninium salts: A prominent effect of iodide anion

Abstract Irradiation of 7-methyl-9-(2,3,5-tri- O -acetyl-b-D-ribofuranosyl)guaninium iodide ( 1a ) in acetonitrile with a 260 nm UV-light resulted in the formation of 2′,3′,5′-tri- O -acetyl-7-methyl-8-oxoguanosine ( 2 ) via a photoinduced electron-transfer oxygenation.

Synthesis of Thymidine Derivatives 3′-Modified with a Polar Three-Atom Group as Potential Anti-HIV-1 Agents

Abstract 3′-Modified thymidine analogs, such as 3′-O-[(methylthio)thio-carbonyl]thymidine (4), 3′-O-thiocarbamoylthymidine (7), and N-(3′-deoxy-thymidin-3′-y1)phosphoramidates (9a, b), were synthesized from thymidine derivatives (1), (5), and (8), respectively, as potential anti-human immunodeficiency virus type 1 (HIV-1) agents. No significant activity against HIV-1 was, however, observed with any of these compounds.

Nucleosides. Part 3.1 Synthesis of 2-N-Substituted 1-β-D-Arabinofuranosylisocytosine Derivatives by The Reaction of 2′,5′-Dichloro-2′,5′-Dideoxyuridine with Amines

Abstract Reaction of 2′,5′-dichloro-2′,5′-dideoxyuridine (1) with ammonia and benzylamine afforded the corresponding 2-N-substituted 1-(5-chloro-5-deoxy-β-D-arabinofuranosyl)-isocytosine derivatives (2 and 10). Reaction of 1 with ammonia, methylamine, cyclohexylamine, and benzylamine followed by treatment with methanolic sodium methoxide gave the corresponding 2-N-substituted 1-(2,5-anhydro-β-D-arabino-furanosyl)isocytosine derivatives (6, 11, and 12).