Total Synthesis of Avellanins A and B, New Fungal Metabolites from Hamigera avellanea with Pressor Effect

Abstract

Avellanins A and B (1 and 2), new pressor-active fungal metabolites from Hamigera avellanea, have been conveniently synthesized from methyl anthranilate. This synthetic study has established the absolute stereostructure of avellanin B (2). Coupling of methyl anthranilate with N-protected amino acid derivatives was best carried out by use of ((9-fluorenylmethyl)oxy)carbonyl (Fmoc)-amino acid chloride. Chain elongation for avellanins was accomplished with diethyl phosphorocyanidate, while cyclization was achieved with diphenyl phosphorazidate.