34818-17-2

Upstream product

• 50496-41-8 ethyl 2-methyl-3,5-dioxoheptanoate 
• 609-14-3 2-acetylpropanoic acid ethyl ester 
• 1402924-45-1 C₁₂H₁₈O₃ 
• 124-38-9 carbon dioxide 
• 7424-54-6 3,5-heptanedione 

Downstream Products

• 57685-79-7 nectriapyrone 

Relevant academic research and scientific papers

Regioselective functionalization of pyrones: Facile synthesis of 6-styrylpyrones via KHMDS-mediated aldol condensation

Herein, we disclose our efforts directed toward the synthesis of the kavalactone-based natural product penstyrylpyrone and other related 4-OMe-2-pyrones possessing diverse substituents at the 3-, 5-, and 7-positions. Further, a facile approach to access 6-styrylpyrones via the KHMDS-mediated regioselective aldol condensation of 2-pyrones is described with moderate substrate scope and good to high yields (58–80%). The utility of this methodology was exemplified by the stereoselective construction of desmethoxyyangonin, asnipyrone A, and asnipyrone B.

Total synthesis of (S)-(+)-ent-phomapyrones B and surugapyrone B

Phomapyrone B (1), the 2-pyrones isolated from the phytopathogenic fungus Leptosphaeria maculans, has been synthesized as the enantiomeric form starting from (S)-2-methylbutanol (4). Surugapyrone B (3) isolated from Streptmyces sp. USF-6280 as an antioxidant has also been synthesized as a natural form. The absolute configuration of phomapyrone B (1) was estimated to be the (R)-form and that of surugapyrone B (3) being the (S)-form. A series of 2-pyrone derivatives 17 have been synthesized through the established procedure and their DPPH radical-scavenging activities have also been evaluated.

Gold- or Silver-Catalyzed Syntheses of Pyrones and Pyridine Derivatives: Mechanistic and Synthetic Aspects

3-Oxo-5-alkynoic acid esters, on treatment with a carbophilic catalyst, undergo 6-endo-dig cyclization reactions to furnish either 2-pyrones or 4-pyrones in high yields. The regiochemical course can be dialed in by the proper choice of the alcohol part of the ester and the π-acid. This transformation is compatible with a variety of acid-sensitive groups as witnessed by a number of exigent applications to the total synthesis of natural products, including pseudopyronine A, hispidine, phellinin A, the radininol family, neurymenolide, violapyrone, wailupemycin and an unnamed brominated 4-pyrone of marine origin. Although the reaction proceeds well in neutral medium, the rate is largely increased when HOAc is used as solvent or co-solvent, which is thought to favor the protodeauration of the reactive alkenyl-gold intermediates as the likely rate-determining step of the catalytic cycle. Such intermediates are prone to undergo diauration as an off-cycle event that sequesters the catalyst; this notion is consistent with literature data and supported by the isolation of the gem-diaurated complexes 12 and 15. Furthermore, silver catalysis allowed access to be gained to 2-alkoxypyridine and 2-alkoxyisoquinoline derivatives starting from readily available imidate precursors.

Total synthesis of infectopyrone, aplysiopsenes A-C, ent-aplysiopsene D, phomapyrones A and D, 8,9-dehydroxylarone, and nectriapyrone

The total synthesis of the 2-pyrone natural products nectriapyrone, aplysiopsenes A-C, ent-aplysiopsene D, phomapyrones A and D, and of 8,9-dehydroxylarone were achieved by Wittig olefination starting with vermopyrone. Infectopyrone was synthesized by Horner-Wadsworth-Emmons reaction starting with phomapyrone D. Racemic phomapyrone C methyl ether was obtained by hydrogenation of nectriapyrone. The total syntheses were achieved starting from commercially available 3,5-heptanedione and led to the desired natural products in 18-46% over 5-6 steps, whereupon all five-step syntheses were carried out with a single chromatographic workup. The total synthesis of infectopyrone, aplysiopsenes A-D, of phomapyrones A and D, and of 8,9-dehydroxylarone were achieved for the first time, giving unambiguous proof for the proposed structures of these natural products.

Total synthesis of neurymenolide-A Based on a gold-catalyzed synthesis of 4-hydroxy-2-pyrones

Treat me gently: For a selective synthesis of the unusually sensitive cyclophanic α-pyrone neurymenolide A, the chosen catalysts must be able to distinguish between six different sites of unsaturation, without scrambling any of the skipped π systems. This challenge was met with a new gold-catalyzed pyrone synthesis in combination with a molybdenum-catalyzed ring-closing alkyne metathesis. Copyright

Convergent syntheses of luteoreticulin and didemethylluteoreticulin

Convergent syntheses of luteoreticulin (1a) and didemethylluteoreticulin (1c) are described which are ammenable to structural variation in both the pyran and phenyl rings.