2H-naphtho[1,8-bc]furan and 8-hydroxy-1-naphthaldehyde

Abstract

Syntheses of 2H-naphtho[1,8-bc]furan (1) are described. It is C-protonated, as are its nitrogen analogues, forming a stable salt; and it is oxidised by air to 8-hydroxy-1-naphthaldehyde. Solvent shifts in the spectra of this aldehyde and related compounds are interpreted in terms of conformational changes caused by hydrogen bonding. Naphthofuran (1) is oxidised by lead tetra-acetate; one of the four products isolated is a dialdehyde (21) structurally similar to gossypol (22).