An efficient synthesis of 7-hydroxy-2,6-dimethylchromeno[3,4-d]oxazol-4-one—a protected fragment of novenamine

The high-yielding six-step synthesis of 7-hydroxy-2,6-dimethylchromeno3,4-d]oxazol-4-one 17 from commercially available 2,4-dihydroxy-3-methylacetophenone is described. Coumarin 17 constitutes a useful synthon for coumarin antibiotic synthesis. A new methodology for oxazole formation applicable to 3-aminocoumarins has been developed, and a mechanistic rationalization is proposed.