Functionalised carbocycles from carbohydrates. Part 4. The synthesis of the epoxy lactone prostaglandin intermediate via bicyclo[3.2.0]heptane derivatives. X-Ray crystal structure of (1R)-5-endo-acetyl-2-exo,3-endo-dibenzoyloxybicyclo[2.2.1]heptane

Abstract

Irradiation of the nona-3,8-dienulose derivative (2) at 350 nm gave the bicyclo[3.2.0]heptyl methyl ketone (3) in good yield. This was converted via the acetate (5) into the corresponding bicycloheptanol (6) which, with base, gave the cyclopentenyl aldehyde (9). This is an intermediate in the preparation of the epoxy lactone (11), a synthetic precursor of the prostaglandins, and this procedure therefore represents a new route to these natural products. With base, compound (3) gave the tricyclic product (4) in good yield. Ring-opening reactions of the latter afford trinorbornane derivatives, one of which, compound (13), was characterised by X-ray diffraction analysis.