Bromofluorination of unsaturated compounds using DMPU/HF as a fluorinating reagent

Abstract

Bromofluorination reactions were performed by treating of a variety of unsaturated compounds with N-bromosuccinimide (NBS) and DMPU/HF as the fluorinating reagent. The DMPU/HF complex showed to be an efficient fluorinating reagent to convert alkenes into their corresponding bromofluoro compounds. It showed to have high reactivity and the process afforded bromofluorinated products with good Markovnikov regioselectivity. These fluorinated compounds are useful starting materials and serve as building blocks for many fluorinated biologically active molecules.

Solventless and metal-free regioselective hydrofluorination of functionalized alkynes and allenes: an efficient protocol for the synthesis of gem-difluorides

“…31 The reaction afforded more difluoride product but also gave an equal amount of sulfate dimer 3a and ketone 4a ( When we increased the reaction temperature to 50 °C, we managed to increase the conversion to product ( Table 1, entry 9). To reduce the dialkenylsulfate product and augment the proportion of difluoride product, we introduced DMPU-12HF, an HF complex with high acidity developed in our laboratory, [32][33][34][35] our reason for this experiment was to increase the concentration of the fluoride source without weakening the acidity of the system. We obtained a higher proportion of difluoride compared to the sulfate byproduct ( Having established the optimal conditions for the hydrofluorination of an alkyne, we explored the substrate scope and functional group tolerance ( Table 2).…”

Hydrogen Bonding: Regulator for Nucleophilic Fluorination

“…Therefore, Hammond and Xu developed the synthetic use of HF/DMPU for several types of organic transformations. [22] …”

“…[22a] The condition for this fluoro-Prins reaction was very mild. The homoallylic alcohols 1a and aldehydes 2 were converted to the desired fluorinated tetrahydropyrans at room temperature within 3 hours when HF/DMPU (10 equiv) was utilized, but a higher temperature (55 °C) was required for synthesis of fluoropiperidines.…”

“…[22b] A wide range of functional groups could be tolerated using this strategy, and it is worth noting that both good regioselectivity and stereoselectivity were observed during the hydrofluorination process. In addition, various N-protecting groups such as Ts (tosyl), Cbz (carboxybenzyl), Fmoc (9-fluorenylmethoxycarbonyl) and Bz (benzoyl) were suitable protecting groups.…”

“…[22c] Good functional group tolerance was observed, and these transformations have been applied mostly to terminal or symmetrically substituted acetylenes. The asymmetrically substituted acetylene such as substituted propargylic ester 12e also showed good regioselectivity.…”