Mo(CO)6-mediated intramolecular Pauson-Khand reaction of substituted diethyl 3-allyloxy-1-propynylphosphonates

Cyclisation of diethyl 3-allyloxy-1-propynylphosphonates with Mo(CO)(6) under PK conditions to give 3-substituted-5-oxo-3,5,6,6a-tetrahydro-1H-cyclopenta[c]furan-4-ylphosphonate, 2a-h, in 45-88% isolated yields was done. The R groups are always syn with H(b) (where applicable). The stereochemistry was determined via both NMR and crystal X-ray analysis.