Diels-Alder Reactions of 12-Hydroxy-9(10®20)-5aH-abeo-abieta-1(10),8(9),12(13)-triene-11,14-dione

Abstract

12-Hydroxy-9(10→20)-5aH-abeo-abieta-1(10),8(9),12(13)-triene-11,14-dione (quinone 2) served as the dienophile in numerous intermolecular Diels-Alder reactions. These cycloadditions were conducted either thermally (including microwave heating) or with Lewis acid activation. While most dienes reacted with quinone 2 in good chemical yield, others were incompatible under the experimental conditions used.

A Concise Synthesis of (+)-Salvadione B

“…Our strategy to prepare salvadione-B is shown in Scheme . We have shown that dienes add to quinone ( S)- 4 from the α-face, thereby creating the requisite relative configurations at C-8, C-9 and C-25 of salvadione-B . The use of triene-selenide 3 in a Diels–Alder reaction raises the question whether it will react as a 2,4- or as a 4,6-disubstituted butadiene.…”

“…Reactions carried out at reaction temperatures below 70 °C produced Diels–Alder adduct 17 and its regioisomer 18 in a 1:1 ratio. When the reaction temperature was maintained at 90 °C, the rate of the retro-Diels–Alder reaction of triene 17 was faster than the retro-cyloaddition rate of 18 , allowing only selenide 18 to be isolated …”