Practical and efficient syntheses of a number of styryl lactones with various structural complexities were accomplished from commercially available and inexpensive D-glycero-D-gufo-heptono-γ-lactone (D-glucoheptonic γ-lactone) (11). Lactone 11 was converted by four sequential reactions (acetonation, selective deacetonation, glycol cleavage oxidation, and Grignard reaction) into key intermediates 3,5-O-isopropylidene-1,1,6-tri-C-phenyl-D-glycero-D-gulo-hexitol (15) and 3,5-O-isopropylidene-1, 1,6- tri-C-phenyl-L-glycero-D-gulo-hexitol (16). The alcohol 15 was transformed via a glycol cleavage oxidation and a Z-selective Wittig reaction into enoate Z-9 which underwent hydrolysis and an intramolecular Michael-type cyclization to give (+)-goniofufurone (1). Likewise, reaction of 16 afforded 7-epi-goniofufurone (2). Acylation and subsequent deacylation of 7-C-phenyl-D-glaco-hept- 2-enono-γ-lactone (20) readily gave (+)-goniobutenolide A (3) and (−)-goniobutenolide B (4), whereas treatment of (Z)-methyl 4,6-O-isopropylidene-7-C-phenyl-L-ido-hept-2-enonate CZ-22) with DBU followed by acid hydrolysis and intramolecular Michael reaction provided (+)-goniopypyrone (5). Mesylation of 4,6-O-isopropylidene-7-C-phenyl-l-ido-hept-2-enono-δ-lactone (27) followed by acid hydrolysis furnished (+)-altholactone (6). (+)-Goniotriol (7) and (+)-7-acetylgoniotriol (8) were readily obtained from the enoate Z-9. This work also provides a viable synthetic route for the construction of the enantiomers of the above styryl lactones for biological evaluation from the same starting material 11. Suggestions about the possible biosynthetic pathway of the styryl lactones are given.
ASJC Scopus subject areas
- Organic Chemistry