Total synthesis of proposed elgonene C and its (4R,5R)-diastereomer

The total synthesis of the proposed elgonene C (1) and its (4R,5R)-diastereomer (1a) has been achieved using a second-generation oxazaborolidinium ion-catalysed Diels-Alder reaction, Sharpless asymmetric dihydroxylation, and a Ni-catalysed cross-carboxyl coupling reaction via redox-active ester (RAE) formation as key reactions. The spectral and analytical data for our synthetic compounds 1 and 1a do not match the isolation data provided by Stadler et al. which indicates that structural revision is required for the proposed elgonene C.

Design and Synthesis of 1,2-Deoxy-pyranose Derivatives of Spliceostatin A toward Prostate Cancer Treatment

We designed and synthesized a novel 1,2-deoxy-pyranose and terminal epoxide methyl substituted derivatives of spliceostatin A using Julia-Kocienski olefination as a key step. With respect to the biological activity, the 1,2-deoxy-pyranose analogue of spliceostatin A suppressed AR-V7 expression at the nano level (IC₅₀ = 3.3 nM). In addition, the in vivo toxicity test showed that the 1,2-deoxy-pyranose analogue was able to avoid severe toxicity compared to spliceostatin A.

Fluorinated triazole-containing sphingosine analogues. Syntheses and in vitro evaluation as SPHK inhibitors

Sphingosine analogues with a rigid triazole moiety in the aliphatic chain and systematic modifications in the polar head and different degrees of fluorination at the terminus of the alkylic chain were synthesized from a common alkynyl aziridine key synthon. This key synthon was obtained by enantioselective organocatalyzed aziridination and it was subsequently ring opened in a regioselective manner in acidic medium. Up to 16 sphingosine analogues were prepared in a straightforward manner. The in vitro activity of the obtained products as SPHK1 and SPHK2 inhibitors was evaluated, displaying comparable activity to that of DMS.

Total Syntheses of Thailanstatins A-C, Spliceostatin D, and Analogues Thereof. Stereodivergent Synthesis of Tetrasubstituted Dihydro- and Tetrahydropyrans and Design, Synthesis, Biological Evaluation, and Discovery of Potent Antitumor Agents

Efficient and selective total syntheses of spliceosome modulating natural products thailanstatins A-C and spliceostatin D are reported. A number of stereoselective methods for the construction of various tetrasubstituted dihydro- and tetrahydropyrans were developed as a prerequisite for the syntheses of these naturally occurring molecules and variations thereof. The pyran-forming reactions utilize a Heck/Saegusa-Ito cascade sequence to generate hydroxy α,β,γ,δ-unsaturated aldehyde precursors followed by a catalyst-controlled oxa-Michael cyclization to furnish tetrasubstituted dihydropyrans with high stereocontrol. Subsequent optimized homogeneous or heterogeneous hydrogenations of these dihydropyran systems afford their tetrahydropyran counterparts, also in a highly stereoselective manner. The synthesized thailanstatins and related analogues were biologically evaluated for their cytotoxic properties, leading to the identification of a number of compounds with exceptionally potent antitumor activities suitable for further development as potential antibody-drug conjugate payloads, single drugs, or drug combinations for cancer therapies. Important structure-activity relationships within the thailanstatin family and structurally related compounds are discussed and are expected to be path-pointing for future studies.

Assembly of Tetrahydropyran Derivatives from Aldehydes, Allylboronates, and Syngas by Asymmetric Relay Catalytic Cascade Reaction

An efficient synthesis of highly enantio-enriched tetrahydropyrans from readily available aldehydes, allylboronates, and syngas has been established by multiply relay catalysis of rhodium and chiral phosphoric acid. The cascade reaction integrates the asymmetric allylboration of aldehydes and alkene hydroformylation, providing a structurally diverse range of products with different workup procedures. The concise synthesis of key chiral building blocks to access herboxidiene and leucascandrolide A demonstrates the high synthetic utility of this method. The cascade reaction employing alkenes to replace aldehydes was also successful.

Re2 O7 -Mediated Dehydrative Cyclization Reactions: Total Synthesis of Herboxidiene and Its 12-Desmethyl Analogue

Re₂ O₇ catalysis effects efficient and stereoselective dehydrative cyclization reactions from monoallylic diols, with stereocontrol arising from thermodynamic equilibration. This method was applied to a rapid synthesis of the spliceosome inhibitor herboxidiene. The route was also utilized for the synthesis of an analogue that highlights the importance of a single methyl group in biasing the conformation in the acyclic region of the molecule.

Total synthesis of (+)-herboxidiene/GEX 1A

An efficient synthesis of herboxidiene is granted from highly stereoselective aldol reactions from two lactate-derived ketones and an oxa-Michael cyclization.