Synthesis of novel spiro[2.3]hexane carbocyclic nucleosides via enzymatic resolution.

[reaction: see text] Novel R- and S-spiro[2.3]hexane nucleosides have been synthesized. The key step involved the Pseudomonas cepacia lipase catalyzed resolution of racemic compound 2, synthesized in seven steps starting from diethoxyketene and diethyl fumarate, to give (+)-acetate 3 and (-)-alcohol 13. (+)-Acetate 3 and (-)-acetate 14 were converted to R- and S-9-(6-hydroxymethylspiro[2.3]hexane)-4-adenine, respectively.