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The molecular and crystal structure of 2′(R)-mercapto-2′-deoxyneplanocin A, C11H13N5O2S M.W.=279.32, has been determined by X-ray analysis. The space group is P212121 with a=10.322(1), b=22.870(2), c=5.273(1)A and z=4. The structure was solved by direct method, and least-squares refinement using 1806 reflections with |Fo| > 30(F) led to the final R value of 0.045. The sugar C(2′) atom is displaced by 0.35A opposite to the base N(9), i.e., C(2′)-exo conformation and the torsion angle about the N(9)-C(1) bond is 26.3(4)° (anti conformation).

Neplanocin A (1) and N6-benzoylneplanocin A (2) were converted to the corresponding 3', 6'-O-(tetraisopropyldisiloxane-1, 3-diyl)-neplanocin A's (3, 4). The 2'-hydroxy group in 3 and 4 was triflated (5, 6). Nucleophilic displacement of 5 and 6 with a number of nucleophiles (I-, Br-, Cl-, N3-, AcO-, AcS-) in hexamethylphosphoric triamide afforded the corresponding 2' (R)-substituted derivatives in high yields. The 2' (S)-azido derivatives were obtained in a similar manner from arabinoneplanocin A prepared by this method. Adenosine was also converted to 2' (R)-substituted derivatives, including arabinofuranosyladenine, as well as 2' (S)-substituted adenosines. The physical properties of these 2'-substituted derivatives of neplanocin A and adenosine, including nuclear magnetic resonance and circular dichroism spectra, are presented.

Phospholipase D from Streptomyces effectively catalyzed the transfer reaction of the phosphatidyl residue from phosphatidylcholines to the 5′-hydroxyl group of nucleosides in a two-phase system. A variety of 5′-phosphatidylnucleosides were easily prepared in high yields by this reaction.

For deoxy analogues of N-acetyl-D-glucosamine and three deoxy-analogues of phenyl N-acetyl-β-D-glucosaminide were synthesized by means of chlorination with sulfuryl chloride and reduction of the chlorides with tri-n-butyltin hydride. The free sugars thus obtained failed to crystallize except for 6-deoxy and 4,6-dideoxy compounds. Phenyl glycosides were mostly crystalline. The yield of chlorination and reduction was generally high.

Phospholipase D from Streptomyces effectively catalyzed the transfer reaction of the phosphatidyl residue from phosphatidylcholines to the primary hydroxyl group of homoserine in a two-phase system. Various phosphatidylhomoserines were easily prepared in good yields by this reaction.

Neplanocin A (I) was treated with 1, 3-dichloro-1, 1, 3, 3-tetraisopropyldisiloxane to give 3', 5'-O-(tetraisopropyldisiloxane-1, 3-diyl) neplanocin A (II), which was converted to the 2'-O-trifluoromethanesulfonyl derivative (III). Nucleophilic substitution of III with a number of nucleophiles (AcO-, AcS-, N3-, Cl-, Br-, I-) in hexamethylphosphoric triamide afforded the respective 2' (R)-substituted derivatives in high yield. The halogenated derivatives were reduced with tri-n-butyltin hydride to the 2'-deoxy compound. 2'-O-Thiocarbonylimidazoyl-3', 5'-O-(tetraisopropyldisiloxane-1, 3-diyl) neplanocin A was also reduced to the 2'-deoxy derivative. The deprotection of the bifunctional silyl group with tetra-n-butylammonium fluoride afforded 2' (R)-AcO, -AcS, -N3, -Cl, -Br, -I, and 2'-deoxy neplanocin A's, respectively. Physical data of these compounds including nuclear magnetic resonance, mass spectrum, and circular dichroism were given.