Retropinacol rearrangement of serratenediol established that either terminal ring of this triterpenoid has the partial structure (A). The accumulated chemical and spectroscopic evidences have been summarized in the structure and stereochemistry (1__=) containing sevenmembered ring for serratenediol, which was confirmed by further degradation into a tricyclic ketone (4__=7__=). The synthesis of this key product has now been achieved. The manner of acid isomerization of serratene derivatives has been also clarified. Serratenediol monoacetate, a minor triterpenoid constituent of Lycopodium serratum, was also established as (3__=), based on ORD examination of various ketonic derivatives.
Stereochemistry of addition reaction to serratene and serratenediol
作者:Y. Tsuda、T. Sano、Y. Inubushi
DOI:10.1016/s0040-4020(01)97871-8
日期:——
Steric course of additionreactions (hydroboration, epoxidation, osmolation, and hydrogenation) to the double bond of serratene derivatives 1 and 17 have been discussed and established as proceeding essentially from a β-direction. For metal reduction of the β-epoxide 3, the stereochemistry of the product is probably controlled not only by conformational stability of the intermediate carbanion but also