42 マキ属植物のノルジテルペンジラクトン類の反応と相互変換

抄録

Reactions of nor-diterpenoid dilactones isolated from Podocarpus plants have been investigated. The 7: 8,9: 11-dienolide type [C] dilactones, the least available but biologically the most active members, are mainly derived from naturally abundant dilactone components of α-pyrone type [A] and 7: 8-epoxy-9: 11-enolide type [B] for total-synthetic and biological purposes. From nagilactone E (5), for example, a combined sequence of hydrogenolysis of 7: 8-epoxide group and dehydration gives nagilactone F (7), 3β-hydroxynagilactone F (8) and 2: 3-dehydronagilactone F (19), which have been found from natural sources. From nagilactone A (1), photo-hydration and concomitant double bond migration of its acetate results in a lactol (22), which is reduced to 1β-hydroxynagilactone F (9), another natural type [C] dilactone. Derivation of the type [A] or [B] from others is not successful. Some attempts for conversion of the ring A functional groups have also been studied.