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The reactions of the ortho-quinones (5a-d) with the phosphorus ylide (6) afforded, besides the expected coumarin derivatives ( l o a d ) , compounds (9d), ( l l b and c), (13), and (14). When the reactions between compounds (5a-d) and (6) were carried out in the presence of ethyl vinyl ether (20) the pyran derivatives (21a, b, and d) and (22a, b, and d) were obtained as main products, by a [4 + 21 trapping process of the ortho-quinone methanide intermediates (7a, b, and d) with the dienophile (20). Similarly, the reaction between compounds (5a) and (6) in the presence of a-methylstyrene afforded mainly the pyrans (23 I and 11). Compounds (16), (19), and (24) were also prepared and studied.

The reaction of phenanthrene-9,lO-quinone ( I ) with the phosphorus ylide (2a) to give compounds (6a), (9a), ( I I ) , and (13) has been reinvestigated. Reaction of ( I ) with the phosphorus ylide (2b) afforded compounds (5b), (6b), and (9b). The transformations (5b) + (6b) and (6b) (5b) have also been studied. When the reactions between (1) and the ylides (2a,b) were carried out in the presence of ethyl vinyl ether both the expected products (17a,b) and (18a,b) and the unexpected products (20a,b) were obtained by a trapping process.

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