Metal-free glycosylation with glycosyl fluorides in liquid SO2

Facile synthesis of sulfonyl fluorides from sulfonic acids

Herein, we demonstrate two complementary strategies for the syntheses of sulfonyl fluorides using sulfonic acids and their salts. One strategy involves the conversion of sulfonic acid sodium salts to sulfonyl fluorides using thionyl fluoride in 90-99% yields in one hour. Lessons learned from the mechanism of this reaction also have enabled a complementary deoxyfluorination of sulfonic acids using Xtalfluor-E® - a bench stable solid - allowing for the conversion of both aryl and alkyl sulfonic acids and salts to sulfonyl fluorides in 41-94% yields. Notably, using Xtalfluor-E® enabled milder conditions and the use of both sulfonic acids and their sodium salts.

Vessel effects in organic chemical reactions; a century-old, overlooked phenomenon

One of the most intriguing aspects of synthetic chemistry is the interplay of numerous dependent and independent variables en route to achieve a successful, high-yielding chemical transformation. The experienced synthetic chemist will probe many of these variables during reaction development and optimization, which will routinely involve investigation of reaction temperature, solvent, stoichiometry, concentration, time, choice of catalyst, addition sequence or quenching conditions just to name some commonly addressed variables. Remarkably, little attention is typically given to the choice of reaction vessel material as the surface of common laboratory borosilicate glassware is, incorrectly, assumed to be chemically inert. When reviewing the scientific literature, careful consideration of the vessel material is typically only given during the use of well-known glass-etching reagents such as HF, which is typically only handled in HF-resistant, polyfluorinated polymer vessels. However, there are examples of chemical transformations that do not involve such reagents but are still clearly influenced by the choice of reaction vessel material. In the following review, we wish to condense the most significant examples of vessel effects during chemical transformations as well as observations of container-dependent stability of certain molecules. While the primary focus is on synthetic organic chemistry, relevant examples from inorganic chemistry, polymerization reactions, atmospheric chemistry and prebiotic chemistry are also covered.

Desulfonative Suzuki-Miyaura Coupling of Sulfonyl Fluorides

Sulfonyl fluorides have emerged as powerful "click" electrophiles to access sulfonylated derivatives. Yet, they are relatively inert towards C-C bond forming transformations, notably under transition-metal catalysis. Here, we describe conditions under which aryl sulfonyl fluorides act as electrophiles for the Pd-catalyzed Suzuki-Miyaura cross-coupling. This desulfonative cross-coupling occurs selectively in the absence of base and, unusually, even in the presence of strong acids. Divergent one-step syntheses of two analogues of bioactive compounds showcase the expanded reactivity of sulfonyl fluorides to encompass both S-Nu and C-C bond formation. Mechanistic experiments and DFT calculations suggest oxidative addition occurs at the C-S bond followed by desulfonation to form a Pd-F intermediate that facilitates transmetalation.