Model studies on construction of the oxabicyclic [3.3.1] core of the mulberry Diels–Alder adducts morusalbanol A and 441772-64-1

Isoprenylated Phenolic Compounds from Morus macroura as Potent Tyrosinase Inhibitors

“…26S, Supporting Information). In the proposed biosynthesis, 3 would be formed via acid-catalyzed regio-and stereoselective intramolecular cyclization from the precursor [17,18], 11, or its epimer at C-3″ in which the orientation of H-4″ and H-5″ and the absolute configurations of C-4″ and C-5″ were definitely trans and R and S, respectively. The orientation of H-5″ and H-6″ and the absolute configurations of C-5″ and C-6″ in 3 were correspondingly determined to be trans and S and R, respectively.…”

Biosynthesis and Biomimetic Synthesis of Flavonoid Diels-Alder Natural Products

“…In their pioneering studies, the callus tissues induced from the leaves or seedlings were cultivated and subjected to selection over a period of 9 years for cell strains with high-pigment productivity [14]. Extraction of these high pigmented cell cultures resulted in isolation of six Diels-Alder adducts, kuwanons J (1), Q (23), R (24), V (25), mulberrofuran E (26), and chalcomoracin (27) along with morachalcone A (28), isobavachalcone (29), and moracin C (30) (Figure 3) [15][16][17][18].…”

“…The structures of metabolites 1, 23−27 suggested that they are either the Diels-Alder adducts from a prenylchalcone and a dehydroprenylchalcone or the Diels-Alder adducts from a prenylchalcone and a dehydroprenyl-2-arylbenzofuran. Nomura and co-workers hypothesized that kuwanon J (1) was an adduct of morachalcone A (28) and dehydroprenylmorachalcone A. Kuwanon Q (23) was an adduct of isobavachalcone (29) and dehydroprenylmorachalcone 13 C-enriched aromatic carbons of chalcomoracin (27) and kuwanon J (1), indicating that both 27 and 1 are derived from two molecules of cinnamoylpolyketide precursors (Figure 4) [19]. From the labeling patterns, the chalcone moiety (34) of both chalcomoracin (27) and kuwanon J (1) is hypothesized to be derived via deoxygenation at C-5 of the cinnamoylpolyketide precursor 31, followed by Claisen condensation and aromatization ( Figure 5) [20].…”

“…During the early studies of the Diels-Alder cycloaddition reaction, the reaction was essentially carried out under thermal conditions owing to the simplicity of the experimental setup Flavonoids -From Biosynthesis to Human Health and the efficiency of the thermal process. Today, thermal promoted Diels-Alder cycloaddition reaction remains the first line approach for the construction of a six-membered cyclic compound, including that of flavonoid Diels-Alder natural products [24][25][26][27][28][29][30].…”

“…Rahman and co-workers utilized the thermal-promoted Diels-Alder reaction to synthesize (±)-dorsterone, (±)-kuwanon V and (±)-morusalbanol A pentamethyl ethers based on the biosynthesis models [27,29,30].…”