DALBERGIA SPECIES .7. ISOLATION AND STRUCTURE OF MELANOXIN - A NEW DIHYDROBENZOFURAN FROM DALBERGIA MELANOXYLON GUILL AND PERR (LEGUMINOSEAE)

The isolation and structure of (-)-melanoxin a new 2,3-dihydrobenzofuran is described. Spectroscopic methods established structure I for melanoxin and confirmation was obtained by synthesis of O-diethyldehydromelanoxin (II, R = Et). Ozonolysis of (-)-melanoxin yielded (-)-(2S,3R)-3-methylmalic acid (III), whilst hydrogenolysis and subsequent ozonolysis gave (+)-(R)-methyl-succinic acid (IV). These experiments show (-)-melanoxin to have a (2S,3S)-configuration. The known (S)-4′-hydroxy-4-methoxydalbergione (V) melannein (VI) and 2,5-dimethoxyquinone were also isolated from Dalbergia melanoxylon. © 1969.