Masking of the γ-lactone as an acetal allowed for an efficient completion of the synthesis through late-stage double carbonyl olefination. The enantiopure acyclic metathesis substrate was readily available by an asymmetric anti aldol reaction. A triple hydroboration/oxidation of the resultant conjugated triene installed three out of four stereogenic centers of the target in a single step.

2021, 23, 1344-1348.Ībstract: The hydroazulene core of the bioactive sesquiterpenoid (−)-dehydrocostus lactone was generated by domino enediyne metathesis.

'Enantioselective Total Synthesis of the Guaianolide (−)-Dehydrocostus Lactone by Enediyne Metathesis'į. Furthermore, an alternative intramolecular Diels-Alder strategy employing a 2-bromo-1,3-diene moiety was investigated. Overall, (−)-salvinorin A was synthesized in only 16 steps starting from 3-furaldehyde with 1.4% total yield. A chemoselective Mitsunobu inversion of a syn 1,2-diol allowed for further streamlining of the original reaction sequence by two steps. As for our previous synthesis of racemic salvinorin A, two intramolecular Diels-Alder reactions were applied to generate the tricyclic core.

The stereogenic center at C-12 was installed by catalytic asymmetric propargylation with excellent enantioselectivity, and the remaining six stereogenic centers were set up highly diastereoselectively under substrate control. 2021, 27, 7968-7973.Ībstract: A concise enantioselective total synthesis of the neoclerodane diterpene (−)-salvinorin A is reported. 'A Protecting-Group-Free Synthesis of (−)-Salvinorin A' Subsequently, the final steps of this approach were improved by using a double carbonyl olefination at the stage of a masked γ-butyrolactone, which completed the synthesis in a much more efficient way. First, oxidation to give a diketo-γ-lactone enabled an enantioselective formal synthesis of the target guaianolide. Multiple hydroboration/oxidation of the resulting hydroazulenes set up three out of four stereogenic centers in a single step. Highly stereoselective asymmetric anti aldol reactions provided the enantiopure substrates for this key step of our synthesis. Our earlier approach by a domino enediyne metathesis was extended by a domino dienyne metathesis strategy to give access to suitably functionalized hydroazulene cores. 2021, 3579-3586.Ībstract: An efficient total synthesis of the sesquiterpenoid (−)-dehydrocostus lactone is reported.

'Asymmetric Total Synthesis of (−)-Dehydrocostus Lactone by Domino Metathesis'į.

Metz pes 6 pc