[reaction: see text] Intramolecular cyclopropanation of a carbene engendered from the corresponding diazo beta-ketoester produced the desired bicyclo[3.1. 0]hexane pseudosugar. Purine nucleosides obtained via Mitsunobu coupling were resolved with adenosine deaminase. The requisite beta-ketoester was assembled in one step from ethyl acetoacetate and acrolein.