Nucleosides from aldonolactones

Synthesis of Nucleosides, Amino Acids, and Other N-Containing Products from Aldonolactones... 

Methyl oxetane-2-carboxylate derivatives (e.g., 284), obtained by ring contraction of aldonolactones, have been employed for the synthesis (279) of the nucleoside / -noroxetanocin [9-(/ -D-eryt/iro-oxetanosyl)adenine, 304] and its a-anomer via an a-chloride obtained by a modified Hunsdiecker reaction. Displacement of chloride by adenine and debenzylation gave 304. The threo isomer of304, /J-epinoroxetanocin (305), was likewise synthesized from D-lyxono-1,4-lactone. The oxetane nucleosides display potent antiviral activity against the human immunodeficiency virus (HIV). 

Compounds 312 were also prepared by alternative routes that comprised cyclocondensation of aldonolactones (313) with 1-hydrazinophthalazines or aldonic acid hydrazides (315) with 1-chlorophthalazines. Their acetates 316 were obtained by direct acetylation of 312 or by condensation of aldonoyl chloride acetates (38) with 1-hydrazinophthalazines (90MI6) (Scheme 96). l,2,4-Triazolo[3,4-a]phthalazin-3-yl acyclo C-nucleosides derived from reducing disaccharides were similarly prepared (90MI2). 

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