Synthesis of tribenzo[b,e,i] [1,6,7]trioxaphenalene and [1]benzopyrano[2,3-d]dinaphtho[2 ', 1 '-b; 1 '', 2 ''-g]oxocine from 4-oxo-4H-1-benzopyran-3-carboxaldehyde

Reaction of 4-oxo-4H-1-benzopyran-3-carboxaldehyde 1 with p-cresol produces mainly the tribenzotrioxaphenalene derivative 3 but under similar conditio n with beta-naphthol, 1 produces a red insoluble quinonoid compound which f inally produces oxocine 6 as the major product when digested with methanol.