Abstract This paper describes synthetic approaches to potential precursors to cyclopropazulenes, a novel class of nonbenzenoid cycloproparenes. The acid-catalysed transannular aldol reaction of 1, 10-dibromobicyclo [8.1. 0] undecane-3, 8-dione (10) gives a single ketol 13 possessing the cyclopropane moiety fused to the five-membered ring. Similar behaviour is observed in the aldol reaction of 27, a benzo-fused analogue of 10. In the ...
