Rhodium Carbenoid Induced [1,2]-Migration in an l-Lyxo-Configured α-Diazo β-Keto Ester: Synthesis of a New Griseolic Acid Analogue

An appropriately substituted α-diazo β-keto ester, prepared from D-glucose, on treatment with a catalytic amount ot dirhodium tetraacetate gave a strained 1,5-dioxabicyclo[3.3.0]octane ring system with concomitant diastereoselective formation of a quaternary carbon substituted with both an ethoxycarbonyl group and a 2-ethoxy-2-oxoethyl group; the product is a key intermediate in the synthesis of a new griseolic acid analogue.