Stereocontrolled syntheses of (-)- and (+)-γ-diisoeugenol along with optically active eight stereoisomers of 7,8'-epoxy-8,7'-neolignan.

ABSTRACT

It was shown that reduction of the tertiary benzylic hydroxy group of (2R,3S,4R,5S)-3,5-bis(4-benzyloxy-3-methoxyphenyl)-2,4-dimethyltetrahydro-3-furanol 17 followed by the intramolecular Friedel-Crafts reaction gave exclusively indane with (7S,7'S,8R,8'R)-2,7'-cyclo-7,8'-neolignan structure 18 along with (7S,7'R,8S,8'R)-7,8'-epoxy-8,7'-neolignan structure 19. Indane 18 was converted to (-)-γ-diisoeugenol ((-)-4). On the other hand, (2S,3R,4R,5S)-3,5-bis(4-benzyloxy-3-methoxyphenyl)-2,4-dimethyltetrahydro-3-furanol 22 did not afford indane, but the tetrahydrofuran structure with (7S,7'S,8S,8'S)-7,8'-epoxy-8,7'-neolignan structure 23 and 7'-epi-23.