| Research Abstract |
The studies on the reaction of Witting reagents with epoxides have been done several researchers more than thirty years. In 1967, Hands and Mercer reported the first isolation of a 1,2lambda^5- oxaphospholane. Enholm and co-workers have reported the sequential Witting-oxyanion accelerated Core reaction of 2,2,2-triphenuyl-5-vinyl-1,2lambda^5-oxaphospholane, which was prepared by the reaction of butadiene monooxide with methylenetriphenylphosphorane. Thus, we tried the synthesis of optically active 1,2lambda^5-oxaphospholanes. Optically pure 1,2lambda^5-oxaphospholanes have been successfully prepared by the action of sodium hydride with optically active 3-hydroxyalkyltriphenylphosphonium salts.
The reaction of 1,2lambda^5-oxaphospholanes with aldehydes afforded the corresponding homoallylic alcohols in nearly quantitative yields (E : Z=2 : 8). Recifeiolide, which is known as an macrocyclic lactone, was synthesized by five step reactions containing this key-step reactin.
On the other hand, 1,2lambda^5-thiaphospholanes could not be isolated by the reaction of 3-mercaptopropyltriphenylphosphonium iodide with sodium hydride. Thus, we found that the reactivity between 3-hydroxyalkylphosphnium salts and 3-mercaptoalkylphoshonium salts was quite different.
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