SYNTHESIS OF ISOMERIC N-(3-FLUORO-2-HYDROXYPROPYL) AND N-(2-FLUORO-3-HYDROXYPROPYL) DERIVATIVES OF PURINE AND PYRIMIDINE-BASES

Reaction of fluoromethyloxirane (III) with heterocyclic bases in the presence of potassium carbonate afforded N-(3-fluoro-2-hydroxypropyl) derivatives of adenine (VI), 3-deazaadenine (VII), 2-amino-6-chloropurine (XII), 6-nitro-1-deazapurine (IX), 4-methoxy-2-pyrimidone (XVIII) and its 5-methyl derivative (XIX). Acid hydrolysis of compounds XII, XVIII, and XIX gave 9-(3-fluoro-2-hydroxypropyl)guanine (XIII), 1-(3-fluoro-2-hydroxypropyl)uracil (XX) and -thymine (XXI). The intermediates XVIII and XIX were ammonolyzed to give 1-(3-fluoro-2-hydroxypropyl)cytosine (XXII) and -5-methylcytosine (XXIII). Reaction of chloro derivative XII with sodium azide followed by hydrogenation of the formed 2-amino-6-azidopurine (XIV) led to 9-(3-fluoro-2-hydroxypropyl)-2,6-diaminopurine (XV). 9-(3-Fluoro-2-hydroxypropyl)-1-deazaadenine (X) was obtained by hydrogenation of compound IX. Benzyloxymethyloxirane (XXIV) was reacted with pyridine-hydrogen fluoride adduct to give 3-benzyloxy-2-fluoropropanol (XXV) whose tosylate XXVI on reaction with sodium salt of adenine and subsequent hydrogenolysis of the intermediate XXVII afforded 9-(2-fluoro-3-hydroxypropyl)adenine (XXVIII). The same compound was obtained by reaction of 3-benzoyloxy-1-bromo-2-fluoropropanol (XXX) with sodium salt of adenine followed by methanolysis. Condensation of sodium salt of XI, XVI, and XVII with synthon XXX and subsequent acid deblocking gave 9-(2-fluoro-3-hydroxypropyl)guanine (XXXIII), 1-(2-fluoro-3-hydroxypropyl)uracil (XXXVI), and 1-(2-fluoro-3-hydro-xypropyl)thymine (XXXVII). 1-(2-Fluoro-3-hydroxypropyl) derivatives of cytosine (XXXVIII) and 5-methylcytosine (XXXIX) were obtained by ammonolysis of the corresponding 4-methoxypyrimidine intermediates XXXIV and XXXV.