EXPERIMENTS DIRECTED TOWARDS THE SYNTHESIS OF ANTHRACYCLINONES .31. REDUCTIVE CLAISEN REARRANGEMENTS OF BIS(ALLYLOXY)ANTHRAQUINONES

A reinvestigation of the reductive Claisen rearrangement of the bis(al lyloxy) anthraquinones (1) and (2) with sodium dithionite of high qual ity has afforded new compounds. These include inter alia diastereomeri c pairs of doubly rearranged leuco 1,4-dihydroxyanthraquinones in the diketo form [(14) and (16); (15) and (17)], products derived from atta ck on or rearrangement to a quinone carbonyl group, e.g. (28) and (29) , and in the case of (1) a 10-deoxygenated 1,4-anthraquinone (21). Str uctures have been assigned from two-dimensional n.m.r. experiments.