Eliminative Deoxofluorination Using XtalFluor-E: A One-Step Synthesis of Monofluoroalkenes from Cyclohexanone Derivatives

The eliminative deoxofluorination of cyclohexanone derivatives using XtalFluor-E is described. The corresponding monofluoroalkenes are obtained in up to 79% yield. Notably, this one-step procedure occurs at room temperature using readily accessible and cost-effective reagents

Exploiting a Difference in Leaving Group Ability: An Approach to β‑Substituted Monofluoroalkenes Using <i>gem</i>-Chlorofluoropropenes

The superior nucleofuge character of chlorine over fluorine was taken advantage of in the selective S_N2′ substitution reaction of <i>gem</i>-chlorofluoropropenes, allowing for the clean formation of β-substituted monofluoroalkenes under metal-free conditions. Numerous <i>N</i>-, <i>S</i>-, <i>O</i>-, and <i>C</i>-nucleophiles behaved nicely in this system. Further synthetic transformations of selected monofluoroalkenes were also accomplished

Introduction of the 4,4,4-Trifluorobut-2-ene Chain Exploiting a Regioselective Tsuji–Trost Reaction Catalyzed by Palladium Nanoparticles

A palladium-nanoparticle-catalyzed Tsuji–Trost reaction of 4,4,4-trifluorobut-2-en-1-yl acetate and ethyl­(4,4,4-trifluorobut-2-en-1-yl)­carbonate was accomplished with various nucleophiles including phenols, amines, and malonates. In the case of the phenols, isomerization of the double bond in the product (up to 20%) was observed as a side reaction. Further synthetic transformations including hydrogenation, the Diels–Alder reaction, and asymmetric dihydroxylation of a product were also examined

S_N2′ Reaction of Allylic Difluorides with Lithium Amides and Thiolates

The synthesis of monofluoroalkenes using an S_N2′ reaction of lithium amides derived from aromatic amines or lithium thiolates with 3,3-difluoropropenes is reported. This transformation features the use of fluoride as a leaving group

Synthesis of Substituted Pentafluorosulfanylpyrazoles Under Flow Conditions

The development of flow conditions for the synthesis of pentafluorosulfanylpyrazoles is reported. A range of alkyl- and aryl-substituted SF5-alkynes were used in combination with different diazoacetates for this transformation. The corresponding substituted SF5-pyrazoles were obtained in up to 90% yield (average of 74% for 21 examples) as a mixture of isomers (up to 73:27 ratio). Synthetic transformations starting from an SF5-containing pyrazole were also demonstrated

Synthesis of Substituted Pentafluorosulfanylpyrazoles Under Flow Conditions

The development of flow conditions for the synthesis of pentafluorosulfanylpyrazoles is reported. A range of alkyl- and aryl-substituted SF5-alkynes were used in combination with different diazoacetates for this transformation. The corresponding substituted SF5-pyrazoles were obtained in up to 90% yield (average of 74% for 21 examples) as a mixture of isomers (up to 73:27 ratio). Synthetic transformations starting from an SF5-containing pyrazole were also demonstrated

Use of XtalFluor‑E as an Alternative to POCl₃ in the Vilsmeier–Haack Formylation of <i>C</i>‑2-Glycals

We report the use of XtalFluor-E ([Et₂NSF₂]­BF₄) as an alternative to POCl₃ in the Vilsmeier–Haack formylation reaction of <i>C</i>-2-glycals. Employing a XtalFluor-E/DMF combination allowed the desired <i>C</i>-2-formyl glycals to be isolated in 11–90% yield. This method was extended to the synthesis of a <i>C-</i>2<i>-</i>formylated disaccharide glycal

Design, Synthesis, and Applications of Potential Substitutes of <i>t</i>-Bu-Phosphinooxazoline in Pd-Catalyzed Asymmetric Transformations and Their Use for the Improvement of the Enantioselectivity in the Pd-Catalyzed Allylation Reaction of Fluorinated Allyl Enol Carbonates

The design, synthesis, and applications of potential substitutes of <i>t</i>-Bu-PHOX in asymmetric catalysis is reported. The design relies on the incorporation of geminal substituents at C5 in combination with a substituent at C4 other than <i>t</i>-butyl (<i>i</i>-Pr, <i>i</i>-Bu, or <i>s</i>-Bu). Most of these new members of the PHOX ligand family behave similarly in terms of stereoinduction to <i>t</i>-Bu-PHOX in three palladium-catalyzed asymmetric transformations. Electronically modified ligands were also prepared and used to improve the enantioselectivity in the Pd-catalyzed allylation reaction of fluorinated allyl enol carbonates

Direct Esterification of Carboxylic Acids with Perfluorinated Alcohols Mediated by XtalFluor‑E

The direct esterification of carboxylic acids with perfluorinated alcohols mediated by XtalFluor-E is reported. The corresponding polyfluorinated esters are obtained in moderate to excellent yields with a broad range of carboxylic acids, including aromatic, heteroaromatic, aliphatic, and nonracemic chiral substrates, using only a slight excess (2 equiv) of the perfluorinated alcohol. Control experiments indicate that the reaction does not proceed through the formation of an acyl fluoride but most likely through a (diethylamino)­difluoro-λ⁴-sulfanyl carboxylate intermediate

Halogenation of Primary Alcohols Using a Tetraethylammonium Halide/[Et₂NSF₂]BF₄ Combination

The halogenation of primary alcohols is presented. The use of a combination of tetraethylammonium halide and [Et₂NSF₂]BF₄ (XtalFluor-E) allows for chlorination and bromination reactions to proceed efficiently (up to 92% yield) with a wide range of alcohols. Iodination reactions are also possible albeit in lower yields