A study towards the synthesis of (-)-atrop-abyssomicin C core

An attempt to synthesize the cyclohexane core of antibiotic abyssomicin C is described. The initial, protecting group-free approach (relying on internal protection) failed and had be modified, in order allow for efficient deprotection acid-sensitive cyclization precursor penultimate synthetic step. Thus, a pyranoside structural unit was used as latent lactone/ester functionality, which deprotected via thioacetalization/hydrolysis/oxidation sequence, give ?-valerolactone-type precursor. Unfortunately, key reaction not feasible, even after modification Reluctance towards turned out general property (at least some) ?7-unsaturated esters, required development new strategy this type transformation.