Reaction between naphthols and dimethyl acetylenedicarboxylate in the presence of phosphites. Synthesis of stable oxa-2λ5-phosphaphenanthrenes, and benzochromene derivatives
The reaction of dimethylacetylenedicarboxylate (DMAD) with 2-naphthol in the presence of trimethyl or triphenyl phosphite leads to stable dimethyl oxa-2 lambda 5-phosphaphenanthrene derivatives in good yields. The reaction of DMAD and trimethyl phosphite in the presence of 1-naphthol or 8-hydroxyquinoline leads to dimethyl 2-(dimethoxyphosphoryl)-3-(1-hydroxy-2-naphthyl)succinate or dimethyl 2-(d