RESUMEN

The asymmetric total synthesis of (+)-lemnardosinane A, a rare rearranged sesquiterpenoid, has been accomplished from (S)-carvone. Key features of the synthesis are the formation of a bicyclo[3.3.1]nonane skeleton using the intramolecular aldol reaction, the stereoselective introduction of an alkyne group, and the stereoselective formation of a tricyclic skeleton via intramolecular pinacol coupling.

RESUMEN

The asymmetric total synthesis of lemnalemnane A, a rare rearranged sesquiterpenoid, has been accomplished in 13 steps from (S)-carvone. The key features of the synthesis are the removal of the isopropenyl group derived from (S)-carvone via a radical intermediate, the formation of the bicyclo[3.3.1]nonane skeleton using the Dieckmann condensation, the stereocontrolled construction of five continuous chiral centers by chemo- and stereoselective reduction and stereoselective introduction of the alkyne group, and the formation of the spirolactone moiety via a hemiacetal intermediate.

RESUMEN

The first total synthesis of phomopsol B has been achieved in a racemic form. The synthesis comprises a deacetylative cyclization to construct a bicyclic skeleton followed by primary alcohol-assisted dihydroxylation, ether cyclization to construct a dioxabicyclo [3.2.1] skeleton and γ-lactone formation based on oxidation by TEMPO.

RESUMEN

The racemic total synthesis of asperaculin A, a sesquiterpenoid lactone with an unprecedented structure, has been accomplished in 17 steps from 3-methyl-2-cyclopentenone. Key features of the synthesis are the construction of a central all-carbon quaternary center using the Johnson-Claisen rearrangement, stereocontrolled introduction of a cyano group, and acid-mediated γ-lactonization.

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RESUMEN

The first total synthesis of applanatumol A has been achieved in a highly stereocontrolled manner. The synthetic method includes assembly of the contiguous chiral centers by convergent Fráter-Seebach alkylation, construction of the seven-membered ring by intramolecular aldol reaction, and stereoselective tandem cyclization to form the tetracyclic skeleton.

RESUMEN

The total synthesis of lucidumone (1), a Ganoderma meroterpenoid, was accomplished in racemic form from easily prepared 6 and 7 in 10 steps as the longest linear sequence. The synthesis was completed through one-pot preparation of the tetracyclic core skeleton by Claisen rearrangement followed by an intramolecular aldol reaction. The intramolecular aldol reaction allowed for the stereocontrolled construction of the bicyclo [2.2.2] octane skeleton fused to an indanone structure. The enantioselective total synthesis of 1 was also described via a chiral transfer strategy in the Claisen rearrangement.

RESUMEN

Leptosperol B, possessing a unique octahydronaphthalene framework and 5-substituted aromatic ring, was isolated from the leaves of Leptospermum scoparium in 2020. The asymmetric total synthesis of leptosperol B was accomplished in 12 steps from (-)-menthone. The efficient synthetic scheme involves regioselective hydration and stereocontrolled intramolecular 1,4-addition to construct the octahydronaphthalene skeleton, followed by the introduction of the 5-substituted aromatic ring.

RESUMEN

The first enantioselective total synthesis of tricyclic diterpenoid callilongisin B, which was isolated from Callicarpa longissima, has been achieved. The synthetic method includes a diastereoselective 1,4-addition and Hosomi-Sakurai allylation followed by Wacker oxidation, intramolecular aldol reaction to construct a six-membered ring, and oxidative dearomatization accompanied by diastereoselective δ-lactonization.

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RESUMEN

The enantioselective total synthesis of nesteretal A was achieved in 15 steps via biomimetic cascade hemiacetalizations at the final key step. Other key features of the total synthesis include Sharpless asymmetric dihydroxylation, diastereoselective 1,2-addition, Pd-catalyzed ene-type cyclization, and stereoselective epoxidation to construct a complex structure containing multiple quaternary carbons.

RESUMEN

Stachyodin A, possessing a unique spirotetrahydrofuran ring system, was isolated from the roots of Indigofera stachyodes in 2018. The first total synthesis of racemic stachyodin A was accomplished in 14 steps. The efficient stereoselective synthetic route involved one-pot Suzuki coupling and stereocontrolled epoxidation followed by reductive opening and spirocyclization.

RESUMEN

Mollebenzylanol A is a tyrosine phosphatase 1B inhibitor isolated from the leaves of Rhododendron molle in 2018 that has a highly functionalized structure. The first enantioselective total synthesis of mollebenzylanol A was achieved in 13 steps from a known chiral starting material. An efficient and practical synthetic scheme was disclosed in a stereocontrolled manner, including stereo/regioselective epoxidation, Eschenmoser-Claisen rearrangement, and stereocontrolled dihydroxylation.

RESUMEN

The first asymmetric total synthesis of isolinearol has been achieved with high stereoselectively. The synthetic method includes enatio- and diastereoselective reductive desymmetrization, stereocontrolled introduction of the methallyl group, regio- and stereocontrolled allylation and introduction of the side chain carbonyl group using olefin cross-metathesis with a pinacol vinyl boronic ester.

RESUMEN

The first total synthesis of the tricyclic meroterpenoid applanatumol B, isolated from Ganoderma applanatum, was accomplished in 14 steps from 2,5-dimethoxybenzaldehyde and 4-pentyn-1-ol. The synthetic features include an intramolecular Morita-Baylis-Hillman reaction, a stereoselective Michael addition, and efficient construction of the tricyclic skeleton under acidic conditions involving epimerization at the α-position of the ketone.

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RESUMEN

The first enantioselective total synthesis of diocollettines A was accomplished in only six steps from a known compound. A short and practical synthetic route was disclosed, featuring an intensive investigation of the stereoselective aldol reaction as a key step using an easily prepared aldehyde moiety and an enone derivative. The synthetic scheme also includes the efficient stereocontrolled construction of the tricyclic skeleton of diocollettines A by intramolecular acetal formation, stereoselective dihydroxylation, and intramolecular ether cyclization.

RESUMEN

A novel chiral 1,3-diketone possessing C2 symmetry was synthesized and utilized in the asymmetric synthesis of guignardone H and I by employing sequential condensation-6π-electrocyclization reactions with the novel 1,3-diketone followed by stereoselective hydrogenation as key steps. Although the synthetic compounds differed from natural guignardone H and I, we realized that the C4-epimers of the proposed structures for guignardone H and I were the actual structures.

RESUMEN

The first total synthesis of racemic chondrosterin I was accomplished. The synthetic features include a Michael addition to incorporate a nitro alkane moiety, an oxidative Nef reaction, intramolecular cyclization of the γ-ketoester derivative, and a desymmetric intramolecular aldol reaction of the meso diketoester compound. The present strategy will be applicable to the synthesis of an optically active form by asymmetric desymmetrization.

RESUMEN

The first asymmetric total synthesis of pleurospiroketals A and B has been accomplished in 16 steps from 5-methyl-5-hexenoic acid. Key features of the synthesis are the highly syn-selective Evans aldol reaction, ring-closing metathesis, highly diastereoselective dihydroxylation and acid-mediated spiroketalization.

RESUMEN

The first enantioselective total synthesis of eremophilane-type sesquiterpenoids, sagittacin E and related natural products, was achieved. This synthesis features an asymmetric desymmetrization by Shi asymmetric epoxidation, intramolecular aldol-type cyclization, allylic oxidation of a 1,4-diene compound, and stereoselective epoxidation.

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RESUMEN

The first total synthesis of tricyclic bisnorsesquiterpene paralemnolide A, isolated from the soft coral Paralemnalia thyrsoides, was achieved. This synthesis features the lactonization of the cyclohexene derivative having a tert-butyl ester via stereoselective epoxidation followed by treatment with a Brønsted acid and construction of the novel tricyclic skeleton by an intramolecular Reformatsky-Honda reaction.

RESUMEN

Enantioselective total synthesis of the proposed structure of furan-containing polyketide was accomplished. The key features include a chemo- and enantioselective epoxidation of 1,4-cyclohexadiene by Shi asymmetric epoxidation, a regioselective epoxide ring opening, chemo- and diastereoselective dihydroxylation of the conjugated dienone derivative, and vinylation of the lactone accompanied by formation of the furan ring.

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