Enantioselective Synthesis of a Fluorinated Analogue of the Orsellinic Acid-Type Twelve-Membered Lactone Lasiodiplodin

Abstract

The chemoenzymatic synthesis of the racemate and the one enantiomer of the fluorinated analogue 8 of the natural cyclooxygenase inhibitor lasiodiplodin is decribed. A lipase-mediated deracemization of the fluorohydrin 18 provided the chiral, nonracemic building block for the enantioselective synthesis of the title compound. The key step was the formation of the 12-membered lactone by a ring-closing metathesis.

Multigram, Chromatography-Free Synthesis of the Flavonol Morin

“…The filtrate was brought to pH 2–3, which led to complete precipitation of all compounds. The major side products arising from fragmentation were revealed to be 4,6-dimethoxysalicylic acid ( 22 , 23%), probably formed by the Baeyer–Villiger reaction and saponification, and 2,4-dimethoxybenzaldehyde ( 9 , 15%) . In addition, we identified ethyl ester 24 and phenolic products 23 and 25 . , 2,4-Dimethoxyphenol ( 25 ) may have been formed by the Dakin reaction of 2,4-dimethoxybenzaldehyde ( 9 ).…”

Studies of organoclays with functionalized pillaring agents

“…Step 1:36, 37 A 11‐bromo‐1‐undecene (4.0 g, 17.15 mmol) solution in acetone (30 mL) in a 100‐mL flask was cooled with an ice/water bath. m ‐Chloroperoxybenzoic acid (≤77%, 5.80 g, and ≤25.88 mmol), dissolved in acetone (20 mL), was added dropwise to this magnetically stirred 11‐bromo‐1‐undecene solution.…”

Regio- and stereoselective synthesis of vicinal fluorohydrins

“…We selectively synthesized several more regioisomeric terminal fluorohydrins either by ring opening with Olah's reagent or KHF 2 in the presence of a crown ether [96][97][98][99][100].…”

“…Kinetic resolution of 1-fluoro-oct-7-en-2-ol was accomplished by lipase-catalyzed acetylation with Candida antarctica lipase (CAL, Novozyme 1 435) and vinyl acetate in cyclohexane to obtain the (R)-(þ)-fluorohydrin and the (S)-(À)-2-acetoxy-1-fluoro-oct-7-ene both with high enantiomeric excess (Scheme 66) [98]. This methodology was also used for the deracemization of fluorinated analogues of the antibiotic ornidazole.…”