45 ジオキサビシクロ[3.2.1]オクタン型多目的キラル合成素子の開発と活用(口頭発表の部)

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Asymmetric dihydroxylation of a series of 2-alkenylfurans afforded the corresponding 1,2-glycols in good to excellent optical yields. On oxidative ring-expansion followed by acid-catalyzed cyclization, the glycols obtained furnished the dioxabicyclo[3.2.1]octane products carrying an enone, a masked formyl and a 1,2-glycol functionalities in their molecules. Owing to their biased bicyclic framework, the reactions around the enone functionality occurred diastereoselectively from the convex face of the molecules which allowed enantio- and diastereo-controlled construction of a variety of natural products having tertiary and quaternary stereogenic centers. In the present paper we demonstrated the general method for the synthesis of the key chiral building blocks and their exploitation for the construction of four insect pheromons having the same framework such as (-)-β-multistriatin, (+)-exo-brevicomin, (-)-exo-isobrevicomin, and both enantiomers of frontalin, both enantiomers of levoglucosenones, five of eight possible hexoses, a cyclitol conduritol F, an insect pheromone serricornin, and a penultimate intermediate of three aromatic bisabolane sesquiterpenes such as (+)-α-curcumene, (+)-nuciferol, and (+)-nuciferal. Two novel nickel-mediated reactions were also discovered during the present investigation: the chemospecific de-O- and de-N-allylation with diisobutylaluminum hydride in the presence of a catalytic amount of NiCl_2-dppp and the coupling reaction of two equivalents of an allyl ether and one equivalent of trimethylaluminum in the presence of a catalytic amount of NiCl_2-dppp.
天然有機化合物討論会の論文
1998-08-31

45 ジオキサビシクロ[3.2.1]オクタン型多目的キラル合成素子の開発と活用(口頭発表の部)

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