Studies toward the enantiospecific total synthesis of rhodexin A.

A new Enantiospecific Route toward Monocarbocyclic Terpenoids: Synthesis of (-)- Caparrapi Oxide

A new and efficient strategy is described for carrying out the enantiospecific synthesis of monocarbocyclic terpenoids from (-)-sclareol (1). The key steps are the Grob scission of l l p toluenesulphonyloxydriman-7ct-ol (2) to give the tobacco seco-sesquiterpene 3 and the Baeyer-Villiger oxidation of 4-[(1'S, 2'S)-2'-formyl-2',6',6'-trimethylcyclohexyl]-2-butanone (4), derived from 3. The first...

Concise Enantiospecific Total Synthesis of Tubingensin A

We report the enantiospecific total synthesis of (+)-tubingensin A. Our synthesis features an aryne cyclization to efficiently introduce the vicinal quaternary stereocenters of the natural product and proceeds in only nine steps (longest linear sequence) from known compounds.

First enantiospecific synthesis of the antitumor marine sponge metabolite (-)-15-oxopuupehenol from (-)-sclareol.

[reaction: see text] A new route toward puupehenone-related bioactive metabolites from (-)-sclareol, based on the palladium(II)-mediated diastereoselective cyclization of a drimenylphenol, is described. Utilizing this, the first enantiospecific synthesis of the antitumor and antimalarial (-)-15-oxopuupehenol, together with improved syntheses of (+)-puupehenone, (+)-puupehedione, and (+)-15-cyan...

Preparation of a functionalized tetracyclic intermediate for the synthesis of rhodexin A.

An efficient synthesis of the tetracyclic steroid core, 19, of rhodexin A and sarmentogenin is reported. An initial inverse-electron-demand Diels-Alder reaction of the acyldiene 6 with the silyl enol ether 7a gave the cycloadduct 8 with the required four contiguous stereocenters in a single step. This compound was then transformed into the methylated enedione 13 which afforded after a reductive...

Enantiospecific first total synthesis of cucumin-H