In Simonis reaction with ethyl acetoacetate naphthalene-2,6-diol gives 8-hydroxy-3-methyl-1 H-naphtho[e,l -b]-pyran-1 -one and naphthalene-2,7-diol gives the related 9-hydroxy isomer. In Pechman reactions, the former diol yields a coumarin, 8-hydroxy-1 -methyl-3H-naphtho[2,1 -b]-pyran-3-one, with the corresponding orientation, but the latter diol gives a coumarin, 8-hydroxy-4-methyl-2H-naphtho[2,3-b]-pyran9-one, with an unusual linear annelation pattern.Benzocoumarins and benzochromones occur as natural phenolic compounds. The first synthesis was carried out by Pechman and Simoni~''~ by acid catalysed condensation of ethyl acetoacetate and phenols and naphthols, respectively. The present paper describes an extension of this reaction to naphthalene-2,6-diol and -2,7-diol, which has disclosed a novel orientational effect.The reaction of 2,6-dihydroxynaphthalene and ethyl acetoacetate under the influence of tetraethylmetaphosphate (PPE) or dilute sulphuric acid (20%) as catalysts gave the chromone (I), 8-hydroxy-3-methyl-1 H-naphtho-[2,1 -b]-pyran-1 -one, the mass spectrum of which shows the retro-Diets-Alder fission characteristic of c h r~m o n e s ,~'~ and giving in this case a fragment at rn/z 186 (rel. int. 16.8) corresponding to the molecular ion [m/z 226 (IOO)] less CH3-Cr CH. Losses of CO fragments follow. A loss of CH4 is characteristic of 2-methyl chromones but not of 4-methyl coumarins. The IR spectrum confirmed the chromone as opposed to a cournarin formula, by a carbonyl band at 1640 cm-', and the 'H-NMR spectrum established the orientation by displaying to AB quartets (J = 8 Hz) due to the aromatic protons.With undiluted sulphuric acid as catalyst, the reaction supplied the isomeric coumarin (II), 8-hydroxy-lmethyl-3H-naphtho[2,1 -b]-pyran-3-one. The mass spectrum characterizes a coumarin by the parent peak (M', m/z = 226, rel. int. = 100) and by intense loss of CO (M-CO, m/z = 198 rel. int. = 69) followed by two further consecutive losses of CO or CHO. There is no loss corresponding to a retro-Diels-Alder cleavage. The IR spectrum for this coumarin showed the requisite carbonyl band at 1680 cm-', while the 'H-NMR spectrum, which was very similar to that of the chromone (I), confirmed the orientation. A marked downfield shift in the methyl resonance only in the coumarin indicated the aromatic ring in (11).
