Selective Halofluorination of Alkenes with Tetrabutylphosphonium Dihydrogentrifluoride in Combination with<i>N</i>-Halosuccinimide or 1,3-Dibromo-5,5-dimethylhydantoin
Alkenes and their functionalized derivatives were readily converted to the corresponding halofluorides with tetrabutylphosphonium dihydrogentrifluoride as combined with N-halosuccinimides or 1,3-dibromo-5,5-dimethylhydantoin in highly regio-, stereo-, and chemoselective manners. In particular, alkenes having a oxirane or primary hydroxyl group also underwent halofluorination selectively in good yields
It was found that potassium fluoride-poly(hydrogen fluoride) salts are useful fluorine sources for halofluorination of alkenes. The reaction proceeded with these salts and N-halosuccinimides or 1,3-dibromo-5,5-dimethylhydantoin in a regio- and stereoselective manner.
Dispersion and Halogen-Bonding Interactions: Binding of the Axial Conformers of Monohalo- and (±)-<i>trans</i>-1,2-Dihalocyclohexanes in Enantiopure Alleno-Acetylenic Cages
means to study the elusive axial/diaxial conformers. X-ray co-crystal structures of AACs further allowed for a detailed investigation, both experimentally and theoretically, on the interplay between space occupancy, guest conformation, and chiral recognition based purely on dispersion forces and weak C-X···π (X = Cl, Br, I) and C-X···||| (acetylene) contacts (X = Cl, Br). The theoretical analysis of
Poly-4-vinylpyridinium Poly(Hydrogen Fluoride): A Solid Hydrogen Fluoride Equivalent Reagent
作者:George A. Olah、Xing-Ya Li、Qi Wang、G. K. Surya Prakash
DOI:10.1055/s-1993-25924
日期:——
Poly-4-vinylpyridinium poly(hydrogen fluoride) (PVPHF), containing 35-60% hydrogen fluoride by weight, was prepared as a solid hydrogen fluoride equivalent reagent. PVPHF with 60% hydrogen fluoride by weight was found to be a versatile fluorinating agent for the hydrofluorination and bromofluorination of alkenes and alkynes, fluorination of alcohols as well as other fluorination reactions. Low hydrogen fluoride content PVPHF (3 equivalents of hydrogen fluoride to 1 equivalent of 4-vinylpyridine unit) was also found to be an efficient reagent for bromofluorination of alkenes in the presence of 1,3-dibromo-5,5-dimethylhydantoin. Fluorosulfonic acid-modified PVPHF showed enhanced reactivities for the fluorination of secondary alcohols.
Synthesis of sp3-Enriched β-Fluoro Sulfonyl Chlorides
作者:Oleksandr O. Grygorenko、Rustam Gurbanov、Andriy Sokolov、Sergey Golovach、Kostiantyn Melnykov、Alexey V. Dobrydnev
DOI:10.1055/s-0040-1706101
日期:2021.5
A three-step approach to the synthesis of sp3-enriched β-fluoro sulfonyl chlorides starting from alkenes is reported. The method was successfully applied to a wide range of acyclic and cyclic substrates, bearing either an exocyclic or an endocyclic double bond. The procedure worked with a wide range of substrates and tolerated a number of functional and protecting groups. Moreover, the target cyclic