Stereoselective synthesis of (−)-synparvolide B

Studies towards the Synthesis of Lepranthin

“…Both isomers (8:2) were separated by column chromatography . The compound 16 was protected as its acetate using acetic anhydride, triethyl amine and DMAP in CH 2 Cl 2 to get the compound 2 in 80% yield . (Scheme ).…”

Stereoselective synthesis of marine macrolide Aspergillide D

“…Thus obtained double bond was subjected to Sharpless asymmetric epoxidation [18][19][20] using (+)-DIPT as a chiral source in presence of Ti(O i -Pr)4 and TBHP at -20 o C to furnish the desired epoxide 6 in good yields. Yadav's protocol 21,22 was applied here for a base induced elimination reaction to give the chiral propargyl alcohol 7 in 90% yield overall covering two steps from the epoxy alcohol (6) using CCl4-Ph3P under reflux conditions followed by reaction with n-BuLi at -20 o C in THF. The hydroxyl functionality in propargyl alcohol 7 was protected as a methoxymethyl ether with MOM-Cl in the presence of DIPEA to afforded compound 8 in excellent yield.…”

Stereoselective total synthesis of lippialactone

“…Finally, a solution of chiral epoxide 12 (0.5 g, 2.57 mmol) in dry THF (10 mL) was added, and after the reaction mixture was stirred for 3 hours at −78°C, it was quenched by adding a saturated aqueous NH 4 Cl solution (20 mL). The resulting mixture was extracted with EtOAc (2×20 mL), and the combined organic layers were dried with anhydrous Na 2 SO 4 Evaporation of the solvent, followed by column chromatography (50% EtOAc/hexane) afforded pure alcohol 13 (R,Z)-6-((4-methoxybenzyl)oxy)hex-2-ene-1,5-diol (14)…”

“…Lippialactone is active against the chloroquine-sensitive D10 strain of Plasmodium falciparum, with a half maximal inhibitory concentration (IC 50 ) value of 9.1 µg/mL, and is known to show mild cytotoxicity. The relative stereochemistry of lippialactone was determined by molecular modeling based on the determination of the relative configuration, by quantum mechanical gauge including atomic orbitals (GIAO) 13 C chemical-shift calculations. Lippialactone (1) is structurally related to synargentolide A (2) (Figure 1), whose structure was revised by our team.…”

“…6 To date, however, only a single report has appeared on the synthesis of 1. 7 In continuation of our interest in the synthesis of bioactive natural δ-lactones, [8][9][10][11][12][13][14] we herein describe a stereoselective total synthesis of lippialactone.…”