Total Syntheses of Aflatoxins M1 and G1 and an Improved Synthesis of Anatoxin B1

Abstract

Starting with 4,6-dihydroxybenzofuran-3[2H]-one (4) the tricyclic phenol 29 was prepared in 11 steps. Condensation of 29 with the vinyl bromide 33 in methylene chloride solution in the presence of zinc carbonate produced racemic milk toxin (3). This new coumarin synthesis seems to be generally applicable and particularly useful whenever acid-sensitive phenols forbid the practice of the classical Pechmann synthesis. An improved synthesis of aflatoxin B1 (1) resulted when the new method was applied to the phenol 42. Finally aflatoxin G1 (2) was prepared analogously from the phenol 42 and the bromo lactone 47. © 1971, American Chemical Society. All rights reserved.