₁₃C-NMR Studies on Marmelo Lactones and Related 2,4-di-Alkylated γ-Lactones

Total Synthesis of Amphidinolide F

“…8.2° (c = 2.12, CHCl 3 ); 1 H NMR (400 MHz, C 6 D 6 ): δ = 7.66 (dd, J = 1.4, 7.9 Hz, 2H), 7.29-7.24 (m, 2H), 7.23-7.17 (m, 1H), 5.72 (s, 1H), 4.07 (ddd,J = 3.8,5.1,7.6 Hz,1H),4.03 (dt,J = 3.3,6.7 Hz,1H),2.71 (ddq,J = 2.6,3.8,7.0 Hz, 1H), 2.52 (dq, J = 3.6, 7.0 Hz, 1H), 2.16 (ddd,J = 5.4,6.7,12.3 Hz,1H), 1.90 (s, 3H), 1.88-1.79 (m, 1H), 1.82 (d, J = 2.4 Hz, 1H), 1.31 (d, J = 7.0 Hz, 3H), 1.23 (d, J = 7.0 Hz, 3H), 1.02 (t, J = 7.9 Hz, 9H), 0.99 (s, 9H), 0.64 (dq, J = 1. 6,8.4 Hz,6H), 0.45 (s, 3H), 0.44 (s, 3H), 0.10 (s, 3H), 0.09 ppm (s, 3H); 13 C NMR (100 MHz, C 6 D 6 ): δ = 158. 6, 140.2, 134.3 (2C), 129.1, 128.2 (2C), 123.0, 85.7, 72.0, 71.8, 71.0, 50.0, 37.6, 31.9, 26.2 (3C), 22.5, 18.3, 16.1, 14.1, 7.3 (3C), 5.6 (3C), 0.5, 0.…”

“…8,6.8,10.1,17.6 Hz,1H); IR (film): 3062, 3001, 2961, 2919, 2872, 1771, 1594, 1488, 1449, 1342, 1218, 1183, 1082, 1043, 950, 751, Compound S8. This compound was prepared by adapting a procedure of Nishida and coworkers: 6 A 500-mL round-bottomed flask, equipped with a magnetic stirbar, an argon inlet and a septum, was charged with diisopropylamine (6.3 mL, 44.9 mmol, 1.4 equiv) and THF (220 mL). The solution was cooled to 78 o C before n-BuLi (1.6 M in hexane, 24.1 mL, 38.5 mmol, 1.2 equiv) was added dropwise to afford a light yellow solution, which was allowed to warm to 0 o C and stirred at this temperature for 15 min.…”

Leucas mollissima, a Source of Bioactive Compounds with Antimalarial and Antimycobacterium Activities

“…Thus, 1 was found to be an epimer of the previously isolated and structurally similar marmelo lactone from the fruit of Cydonia oblonga Mill. (Rosaceae) [6], and hence identified as a new natural product, (2 S, 4R, 6 S)-2,6-dimethyl-6 hydroxy-7-ene-4-olide, belonging to the class of (−) epi-marmelo lactones. Compound 2 was identified as schensianol A by comparing its NMR data from a previously reported article in which it was isolated from Euonymus schensianus Maxim.…”

Stereoselective Synthesis of the C1–C16 Fragment of the Purported Structure of Formosalide B

“…The synthesis of phosphonate fragment 5 was started from the well-known TBDPS ether derivative 7 of ( S )-5-hydroxymethyl-2,3-dihydrofuran-2­(3 H )-one, which was readily prepared from l -glutamic acid (Scheme ). The lactone 7 was reduced with DIBAL-H at −78 °C, and the resulting hemiacetal was immediately allowed to undergo Wittig olefination using (ethoxycarbonyl-methylene)­triphenyl phosphonate to provide the corresponding δ-hydroxy α,β-unsaturated ester as a mixture of geometrical isomers (95% of E -isomer confirmed by 1 H NMR). The minor ( Z )-isomer was then easily separated from the major ( E )-isomer 9 by column chromatography.…”