Mapping the chemical reactivity of polyquinanes produced by 2-fold addition of vinyl anions to squarate esters. A bicyclic case study

A highly oxygenated diquinane representative of the product class obtained from the condensation of squarate esters with a pair of vinyl anions has been subjected to a battery of chemical reactions for the purpose of achieving utilitarian functional group transformations. Reduction with lithium aluminum hydride proceeds predominantly, but not exclusively, by 1,4-reduction. Dehydration of the gamma-hydroxy-alpha,beta-(bisalkoxy)cyclopentenone to extend conjugation into the B ring was achieved via chlorination and subsequent removal of HCl. Access to dienone 12 in this manner has opened the door to reductive removal of the gamma-hydroxyl substituent, to angular methylation, and to allied chemical changes. The global results disclose that the previously unknown functional group array present in 5 and its congeners is amenable to convenient modification, thereby providing the backdrop for more advanced annulation and structural elaboration. The prospects for utilization of the several new compound types as serviceable building blocks are considered to be numerous.