The synthetic applications of organomercurials arising by the cleavage of cyclopropane derivatives.

Organomercurial esters 2a-c obtained from cyclopropyl alcohols la-c in three or five (depending on whether the system is cis or trans) steps, react with organocuprates via an intramolecular addition across the carbonyl bond to generate the corresponding lactolate. Quenching of the latter intermediate with water leads to the lactol 3a, c in the cycloheptane and cyclopentane series, whereas the open hydroxyketone 4b is formed in the cyclohexane series. Quenching of the lactolate with BF3 Et2O gives different products, as demonstrated for the cyclohexane series. The Pd(II)-catalysed carbonylation of chloromercurio alcohols 5a-c allows the construction of either cis- or trans-fused lactone rings 6a-c. The stereochemistry of the lactone annulation is controlled by the Hg (II) reagent to initially open the cyclopropane ring, in conjunction with oithogonal protection.