Synthesis of Vlasouliolides: A Pathway toward Guaiane–Eudesmane C₁₇/C₁₅ Dimers by Photochemical and Michael Additions

Abstract

Vladimiria souliei is a plant found in China used in traditional medicine. Recent isolation studies have led to the discovery of vlasouliolides, which are natural sesquiterpene dimers. However, the yields obtained from isolation have proven to be really low (<0.01%), greatly hindering the study of these molecules. In this work, we propose a simple synthetic route to obtain different vlasouliolides in good yields from dehydrocostuslactone and costunolide, which will lead to further bioactivity studies at a higher scale.

Synthesis of Pertyolides A, B, and C: A Synthetic Procedure to C17-Sesquiterpenoids and a Study of Their Phytotoxic Activity

“…30 Accordingly, during the workup of the reaction, the The complete deprotection of the ketals 12 and 13 was performed by transketalization in an acetone:H 2 O 95:5 mixture with catalytic amounts of p-TsOH according to the procedure described in the literature. 27 This procedure produced pertyolide A (1) and B (2) both as crystalline solids in 89% and 95% yields, respectively. The NMR and the spectroscopy data of the synthesized 1 and 2 match those reported in the bibliography 18 (see Table S1 for more detailed NMR data and Tables S6 and S7 for a comparison with the NMR data reported for the isolated 1 and 2).…”

“…After successfully isolating the starting materials, we applied the synthesizing routes shown in Schemes and to obtain pertyolides A, B, and C. Compounds 1 and 2 were synthesized in four steps. The photochemical addition of acetaldehyde to the starting sesquiterpene lactones yields the 1,4-dicarbonyl derivatives 7 (68% yield) and 8 (54% yield) with a C 17 skeleton following the procedure described in the literature. − (For NMR data, see Table S3, Supporting Information).…”

“…The complete deprotection of the ketals 12 and 13 was performed by transketalization in an acetone:H 2 O 95:5 mixture with catalytic amounts of p -TsOH according to the procedure described in the literature . This procedure produced pertyolide A ( 1 ) and B ( 2 ) both as crystalline solids in 89% and 95% yields, respectively.…”

Bioprospection of Phytotoxic Plant-Derived Eudesmanolides and Guaianolides for the Control of Amaranthus viridis, Echinochloa crus-galli, and Lolium perenne Weeds

“…Compound 17 , a derivative of DHC ( 10 ) with a 2-hydroxypropyl group at C-11, was obtained by photochemical addition of acetaldehyde at C-13 followed by the reduction of the carbonyl group with NaBH 4 (Figure ). Treatment of DHC (100 mg, 0.434 mmol) gave the desired methyl ketone in 70% yield. In the second step, the methyl ketone (20.0 mg, 0.073 mmol) was dissolved in anhydrous MeOH (5.0 mL) at 0 °C (water/ice bath) under N 2 and NaBH 4 (50.3 mg, 1.4 mmol) was added.…”

“…An unsuccessful attempt was made to purify the epimeric mixture by analytical HPLC. The structure of 17 was confirmed by comparison of its 1 H NMR spectroscopic data (Figure S8.8) with previously reported data …”