4,9,14,19-TETRAFUNCTIONALIZED PAGODANES - DENOVO SYNTHESIS - FUNCTIONAL-GROUP MANIPULATIONS

Various 4,9,14,19-tetrafunctionalized pagodanes are prepared by a de novo route commencing from appropriately substituted isodrin analogues (3, 4). With the 14,19-dimethoxypagodane-4,9-dcarboxylic esters 30/31, isolated after 16 one-pot operations (ca. 40 functional changes) in ca. 6.5% overall yield (ca. 84% per operation, ca. 93% per functional change), the scope for further functional group manipulations on the pagodane sphere is explored (e.g. diketone dicarboxylic ester 35, dimethoxy diketone 37, tetraketone 41). In two face-to-face dibenzo substrates (17, 49), clean photoquilibration with the corresponding syn-o,o'-dibenzo isomers (19, 50) (75:25 and 80:20, resp.) is observed upon direct excitation (lambda = 254 nm).