Mikio Honjo

Synthesis of uracil-5- and adenine-8-phosphonic acids

Abstract Successive treatments of 5-bromo-2,4-dimethyoxypyrimidine (I) with n-butyllithium and diethyl chlorophosphonate followed by dealkylation afforded uracil-5-phosphonic acid (V). Adenine-8-phosphonic acid (IX) was also prepared by a similar method, starting from 6-chloro-9-(tetrahdyro-2-pyranyl)purine (VI).

Direct fluorination of 6-O-cyclouracil nucleosides.

Abstract Direct fluorination of 6-O-cyclouracil nucleosides gave 6-O-dicyclo-5,5-difluoro-5,6-dihydrouracil nucleosides in one step and no monofluoro compounds were obtained.

Photochemical Synthesis of Phosphonopyrimidine and Phosphonopurine Ribonucleosides

Abstract Photochemical reaction of 2′,3′-di-O- or 2′,3′, 5′-tri-O-protected 5-bromouridine (1), 8-bromoadenosine (4) and 8-bromoguanosine (10) with triethyl phosphite in a mixture of dimethyl formamide (DMF) and acetonitrile, followed by deprotection, provided the corresponding diethyl phosphonate derivatives (3, 7 and 12).

Structure of Ethyl Hydrogen P(R), 5′-Anhydro-2′,3′-O-Isopropylidene-Adenosine-8-Phosphonate Hemiethylacetate Solvate

Abstract The crystal, and molecular structure of the title compound [8,5′-P-cyclo-A(R)] was determined by the X-ray diffraction method. It crystallizes in space group C2221 with unit-cell dimensions a=14.222(3), b=13.879(4), c=43.612(8) A. There are two 8,5′-P-cyclo-A(R) molecules and one ethyl acetate molecule per asymmetric unit. The two cyclonucleosides have a very similar overall conformation; the glycosidic torsion angle is in the anti range, the hetero-cyclic ring between the base and sugar moieties being in the endo form, while the sugar ring conformation is C(3′)-exo. The two independent cyclo-nucleoside molecules form a hydrogen bonded dimer N(1)—H-N(6) [3.07(2) A] and N(6)-H—O(6)(the free oxygen atom of the phosphonate group) [2.99(2) A].