Catalytic Sulfamoylation of Alcohols with Activated Aryl Sulfamates

Intramolecular Friedel-Crafts Reactions of Sulfamoyl Fluorides, Fluorosulfates, and Sulfuramidimidoyl Fluorides

Sultams are valuable heterocycles with numerous applications, particularly as pharmacophores. Previous syntheses of these compounds usually require metal-catalyzed cyclization or multiple-step processes. Here, we report a straightforward strategy for accessing these important motifs by developing the intramolecular Friedel-Crafts cyclization of sulfamoyl fluorides under mild conditions. Our protocol also accommodates fluorosulfates and sulfuramidimidoyl fluorides, which are rarely utilized in Friedel-Crafts reactions.

Synthesis of Oxabicyclo[3.2.1]octan-3-ol Scaffold via Burgess Reagent Mediated Cyclodehydration of δ-Diols under Acidic Conditions

Dehydrative cyclization of δ-diols was achieved by using the Burgess reagent under mild conditions to furnish a novel oxabicyclo[3.2.1]octan-3-ol scaffold. The stereochemistry of the generated oxabicyclic compounds was assigned based on single X-ray crystallography and 2D-NMR experiments.

Exploration of One-Pot, Tandem Sulfamoylation and aza-Michael Cyclization Reactions for the Syntheses of Oxathiazinane Dioxide Heterocycles

We show the first examples of one-pot tandem sulfamoylation/aza-Michael reactions for the preparation of oxathiazinane dioxide heterocycles from linear alkenyl alcohol precursors. Our optimized protocols are tolerant of a variety of functional groups and provide products that are amenable for further transformations. The reactions scale well, and no special precautions are required to exclude air or ambient moisture.

Metal-free introduction of primary sulfonamide into electron-rich aromatics

We report herein a direct and practical synthesis of arylsulfonamides from electron-rich aromatic compounds by using in situ generated N-sulfonylamine as the active electrophile. Substrates include derivatives of aniline, indole, pyrrole, furan, styrene and so on. The reaction proceeds under mild conditions and tolerates many sensitive functional groups such as alkyne, acetate, the trifluoromethoxy group or acetoxymethyl ester. Applications of this method for the construction of metal ion sensors and fluorogenic dye have been demonstrated, thus highlighting the potential of this method for probe development.

Observation of the Water-HNSO2 Complex

Sulfamic acid (NH2SO3H, SFA) is supposed to play an important role in aerosol new particle formation (NPF) in the atmosphere, and its formation mainly arises from the SO3-NH3 reaction system in which weakly bonded donor-acceptor complexes such as SO3···NH3 and isomeric HNSO2···H2O have been proposed as the key intermediates. In this study, we reveal the first spectroscopic observation of HNSO2···H2O in two forms in a solid Ar matrix at 10 K. The major form consists of two intermolecular H bonds by forming a six-membered ring structure with a calculated dissociation energy of 7.6 kcal mol-1 at the CCSD(T)-F12a/aug-cc-pVTZ level of theory. The less stable form resembles SO3···H2O in containing a pure chalcogen bond (S···O) with a dissociation energy of 7.2 kcal mol-1. The characterization of HNSO2···H2O with matrix-isolation IR spectroscopy is supported by D- and 18O-isotope labeling and quantum chemical calculations.

Sulfur(iv) reagents for the SuFEx-based synthesis of substituted sulfamate esters

Sulfur(vi) fluoride exchange chemistry has been reported to be effective at synthesizing valuable sulfur(vi) functionalities through sequential nucleophilic additions, yet oxygen-based nucleophiles are limited in this approach to phenolic derivatives. Herein, we report a new sulfur(iv) fluoride exchange strategy to access synthetically challenging substituted sulfamate esters from alkyl alcohols and amines. We also report the development of a non-gaseous, sulfur(iv) fluoride exchange reagent, N-methylimidazolium sulfinyl fluoride hexafluorophosphate (MISF). By leveraging the reactivity of the sulfur(iv) center of this novel reagent, the sequential addition of alcohols and amines to MISF followed by oxidation afforded the desired substituted sulfamates in 40-83% yields after two steps. This new strategy expands the scope of SuFEx chemistry by increasing the accessibility of underdeveloped -S(O)F intermediates for future explorations.

Kukhtin-Ramirez-Reaction-Inspired Deprotection of Sulfamidates for the Synthesis of Amino Sugars

Herein, we present a mild strategy for deprotecting cyclic sulfamidates via the Kukhtin-Ramirez reaction to access amino sugars. The method features the removal of the sulfonic group of cyclic sulfamidates, which occurs through an N-H insertion reaction that implicates the Kukhtin-Ramirez adducts, followed by a base-promoted reductive N-S bond cleavage. The mild reaction conditions of the protocol enable the formation of amino alcohols including analogs that bear multiple functional groups.

Catalyst-Controlled, Site-Selective Sulfamoylation of Carbohydrate Derivatives

Methods for site-selective sulfamoylation of secondary hydroxyl groups in pyranosides are described. Using a boronic acid catalyst, selective installation of a Boc-protected sulfamoyl group at the equatorial position of cis-diols in manno- and galacto-configured substrates has been achieved. Activation of trans-diol groups in gluco- and galacto-configured substrates is also possible by employing an organotin catalyst.

Preparation of Sulfamates and Sulfamides Using a Selective Sulfamoylation Agent

Sulfamates and sulfamides are prevalent in biological molecules, but their universal synthetic methods are limited. We herein report a sulfamoylation agent with high solubility and shelf stability. Various sulfamates and sulfamides can be synthesized directly from alcohols or amines by employing this agent with high selectivity and high yields. This protocol was also successfully used for late-stage sulfamoylation of pharmaceuticals containing a hydroxyl or amino group.

Photochemistry of HNSO2 in cryogenic matrices: spectroscopic identification of the intermediates and mechanism

Small molecules solely consisting of H, N, O, and S are highly relevant intermediates in atmospheric chemistry and biology. Even though several isomers of [HNO2S] have been computationally predicted, only the IR spectra for the two lowest-energy isomers HNSO2 and syn-syn HONSO have been previously reported. Herein, the photochemistry (193 nm laser) of HNSO2 in N2-, Ne-, and Ar-matrices (≤15 K) has been studied. Aside from syn-syn HONSO, several new isomers including anti-syn HONSO, gauche-syn HOSNO, syn HOS(O)N, anti HOS(O)N, syn HS(O)NO, anti HN(O)SO, gauche-syn HSONO, and an elusive caged-radical pair HOS˙˙NO have been identified. Additionally, the formation of fragments HONO, HO˙, ˙NO, and ˙NO2 has also been observed. The characterization of these species with matrix-isolation IR and UV/Vis spectroscopy is supported by 15N-labeling and quantum chemical computations at the B3LYP/6-311++G(3df,3pd) level. Furthermore, the photo-induced isomerization reactions, including the conformational conversion of syn-syn HONSO → anti-syn HONSO and reversible isomerization of HOSNO ↔ anti-syn HONSO, syn-syn HONSO ↔ HN(O)SO, HSONO ↔ HS(O)NO, and HOS˙˙NO ↔ HOSNO have also been observed, and the underlying mechanism is discussed.