6:7-benzocoumaranone

Abstract

6-7-Benzocoumaranone was first described by Ullmann who prepared it by the cyclization of 2-bromacetyl-1-naphthol and recorded the m.p. 91–2°. Fries prepared it later by the intramolecular acylation of α-naphthoxyacetyl bromide and recorded the m.p. 119°. A compound of the same m.p. prepared similarly from α-naphthoxyacetyl chloride has been considered by Inghamet al., to beperinaphthapyrone. 6∶7-Benzocoumaranone, m.p. 119°, has now been synthesised by an unambiguous route, starting from 1-hydroxy-2-naphthoic acid through the intermediate diazoketone, and it has been shown that the product obtained by Inghamet al. was 6∶7-benzocoumaranone.