Reactions of Diels-Alder adducts of a sugar-derived dihydropyranone leading to fused polycyclic compounds.

IRIARTE CAPACCIO, CHRISTIAN A.; VARELA, OSCAR

CARBOHYDRATE RESEARCH

Elsevier

Año: 2004 vol. 339 p. 1207 - 1213

0008-6215

Manipulation of the ketone and alkene functions of cycloadducts 2, 3, and 4, derived from optically active (ee > 86%) (S)-2-benzyl-2H-pyran-3(6H)-one (1), led to polycyclic systems having three or four fused rings. Reduction of the carbonyl group of the butadiene adduct (2) took place with low facial selectivity affording the alcohols 5 and 6 in 1:1.4 ratio. In contrast, a higher diastereoselection was observed for the reduction of the carbonyl of the cyclopentadiene adducts 3 and 4 to give the endo alcohols 10 and 13, respectively. The epoxidation of 6 showed low facial selectivity in the formation 7 and 8, whereas epoxidation of 10 and 13 took place from the exo face of the norbornene system to give spontaneously the polycyclic alcohols 11 and 14 by opening of the epoxide by intramolecular attack of the hydroxyl group of the pyranoid ring. Similarly, addition of iodine to 10 led to the polycyclic iodide 12. Keywords: Cyclizations; Cycloadducts; Diels-Alder; Dihydropyranones.