Experiments Directed Towards the Synthesis of Anthracyclinones. XXVII. Transformations of 2,3-Bisalkynyl and 2,3-Bisalkenyl Anthraquinones

2,3-Bisalkynyl anthraquinones have been synthesized and their behaviour under Bergman-type cyclization conditions has been studied. Cyclization reactions of 2,3-bis(propenyl)anthraquinones yield a number of products, mechanisms for the formation of which are proposed. An attempt to elaborate an A-ring from the 2,3-allyl side chains of the bisallylated anthraquinone (32) is reported.