Improvements have been made in the use of acylated pyridinium ylides for the transformation of 2-methyl-1,4-naphthoquinone into derivatives (15) and (16) of naphtho[2,3-c]pyran-5,10-dione, containing furan and thiophene groups. The substitution and cyclisation steps can be combined effectively by using 2-phenoxymethyl- instead of 2-methyl-naphthoquinone. The use of better leaving groups than phenoxy (especially 4-nitrophenoxy) allows the quinone to react with two proportions of ylide and leads regiospecifically to 1-aroyl-2-arylanthracene-9,10-diones such as (20a). If the leaving group is nuclear bromine as in 2-bromo-3-methyl-1,4-naphthoquinone, another reaction with 2 mol equiv. of ylide leads to complex red intermediates of type (31) which in contact with alumina are quantitatively converted into the regioisomeric 2-aroyl-3-aryianthracene-9,10-diones such as (22a).

The structures have been determined by standard methods but special features of the NMR spectra are reported including a case of extreme line broadening by traces of iron. Mechanisms are suggested for the diverse reactions between the quinones and the ylides.