Preparation of fluorolactones from the reaction of γ-ketoacids with diethylaminosulfur trifluoride

Chaetoglobosins from Chaetomium globosum, an Endophytic Fungus in Ginkgo biloba, and Their Phytotoxic and Cytotoxic Activities

“…Rearrangement reactions are sometimes observed in DAST fluorination. 32−34 For example, preparation of γ-fluorobutyrolactones from the reaction of γ-ketoacids with DAST was reported by Chen et al 34 In the current work, similarly, the mechanism of oxolane ring formation between C-20 and C-23 in 10 is postulated to occur via the pathway (Figure 3). The 35,36 Consequently, an inversion of the configuration of C-20 in the resulting 10 took place, which was further confirmed by the cross-peak between H-8 and H-20 in the ROESY spectrum of 10 (Figure 2).…”

“…32−34 For example, preparation of γ-fluorobutyrolactones from the reaction of γ-ketoacids with DAST was reported by Chen et al 34 In the current work, similarly, the mechanism of oxolane ring formation between C-20 and C-23 in 10 is postulated to occur via the pathway (Figure 3). The The configuration of the core skeleton, 10-(indol-3-yl)- [13]cytochalasan, in these chaetoglobosins could be assigned on the basis of the biosynthesis with those of chaetoglobosin A (1) 21 as well as on a ROESY experiment.…”

“…Rearrangement reactions are sometimes observed in DAST fluorination. − For example, preparation of γ-fluorobutyrolactones from the reaction of γ-ketoacids with DAST was reported by Chen et al In the current work, similarly, the mechanism of oxolane ring formation between C-20 and C-23 in 10 is postulated to occur via the pathway (Figure ). The first step is the nucleophilic displacement of fluorine on sulfur by oxygen of the 20-OH accompanied by elimination of hydrogen fluoride to give the intermediate 7a .…”

Levulinic acid in organic synthesis

“…193 Combination of halogenation and dehydrohalogenation of LA affords halogen-containing hydroxyfuranones 84a,b. 194,195 Sulfur tetrafluoride 196 ± 198 and its derivatives 199 are the most effective fluorinating agents for LA. However, this does not involve the methyl and the methylene groups.…”

Amide Formation Using In Situ Activation of Carboxylic Acids with [Et2NSF2]BF4

“…In summary, we showed that XtalFluor‐E is a useful reagent for the preparation of amides from carboxylic acids and amines. Though the exact mechanism has not been elucidated, our results suggest the intermediate formation of an activated ester between the acid and XtalFluor‐E (see Figure 1),16–18 which is in contrast to the acyl fluoride that is generated when Deoxofluor is employed 13…”