Stereochemical aspects of the biological oxidation of aryl isoprenoids. The asymmetric synthesis and absolute configuration of meranzin and of meranzin hydrate

Antifungal Activity of <I>Diplotaenia damavandica</I>

“…Identi®cation of the constituents was established by spectroscopy and comparison with the literature and authentic samples. Data were in agreement with the reported values for angelicin (Batterham & Lamberton 1964;Seshadri & Sood 1967;Steck & Mazurek 1972;Bose et al 1979), libanorin (Bohlmann & Grenz 1969Perelson et al 1971), psoralen (Elgamal et al 1979), and auraptene (meranzin) (Grundon & McColl 1975). The structures of the isolated coumarins from D. damavandica are shown in Figure 1.…”

Multidimensional liquid chromatography for the determination of chiral coumarins and furocoumarins in Citrus essential oils

“…4‐[(3,3‐dimethyloxiran‐2‐yl)methoxy]‐7‐H‐furo[3,2‐g]chromen‐7‐one (oxypeucedanin): Pale yellow crystals from n ‐hexane, Mp 141–142°C, [α] D = +15.5° (0.4 CHCl 3 ) ([], +13.4° CHCl 3 ), 1 H‐NMR and 13 C‐NMR data is provided in another study []. 9‐[(3,3‐dimethyloxiran‐2‐yl)methoxy]‐4‐methoxy‐7‐H‐furo[3,2‐g]chromen‐7‐one (byakangelicol): Light yellow crystals from n ‐hexane, Mp 53–60°C, [α] D = +35.6° (0.4 pyridine) ([], +34.7° pyridine), 1 H‐NMR and 13 C‐NMR datais provided in another study [].…”

“…4‐[(E)‐3‐Methyl‐5‐(3,3‐dimethyloxiran‐2‐yl)pent‐2‐enyloxy]‐7‐H‐furo[3,2‐g]chromen‐7‐one (epoxybergamottin): Colourless crystals from n ‐hexane, Mp 69–70°C, [α] D = +2.4° (1 CHCl 3 ) ([], +4.6° CHCl 3 ), 1 H‐NMR and 13 C‐NMR data is provided in another study []. 7‐Methoxy‐8‐[(3,3‐dimethyloxiran‐2‐yl) methyl]‐2H‐chromen‐2‐one (meranzin): white crystals from hexane, Mp 94–97°C, (Mp 97–98°C []), [α] D = −22.3° (0.25 CHCl 3 ) ([], −1.5° CHCl 3 ). 1 H‐NMR (300 MHz, CDCl 3 ) δ :1.28 (s, 3H); 1.33 (s,3H); 3.03(dd, 1H, J = 6.5, 10.8 Hz); 3.13 (dd,1H, J = 6.5, 10.8 Hz); 3.22(dd, 1H, J = 4.5, 6.5 Hz); 4.02 (s, 3H), 6.24 (d, 1H, J = 9.8 Hz); 6.86 (d, 1H, J = 2.7 Hz); 7.41 (d, 1H, J = 9.8 Hz), 7.63 (dd,1H, J = 9.5,1.7 Hz); 13 C‐NMR (75 MHz, CDCl 3 ) δ :18.0, 24.6, 24.8, 55.9, 56.5, 73.0, 107.5, 112.9, 113.2, 114.1, 127.2, 143.9, 153.3, 160.7, 161.1.…”

Veprisinium Salt, A Novel Antibacterial Quaternary Alkaloid from Vepris louisii

“…The assignment of the S configuration to (I) and the existence of other (+)-isomers in this series with possible S-configuration [9,10] are however not in line with GRUNDON and MCCOLL'S suggestion that dihydrofuroquinolines are biosynthesized from 2-quinolones like (IV) via a highly stereospecific Sepoxide [17] and points to the fact that formation via the alternate R-epoxide might also be a possibility.…”

“…Dequaternisation of veprisinium iodide with anhydrous pyridine at 80° [12] afforded the laevorotatory 4-quinolone, (-)-2-(1-hy- The Absolute Configuration of (-)-Veprisinium salt As only one asymmetric centre exists in (-)-veprisinium cation, its absolute configuration should be S since Grundon and his collaborators have shown through their extensive asymmetric syntheses of dihydrofuroquinoline alkaloids [14,15,16,17] that the (+)-isomer in this series has the R configuration.…”