Sulfamates and their therapeutic potential

One-Flow Syntheses of Unsymmetrical Sulfamides and N-Substituted Sulfamate Esters

We developed one-flow syntheses of unsymmetrical sulfamides and N-substituted sulfamate esters by changing a nucleophile and a tertiary amine from inexpensive and commercially available chlorosulfonic acid. In the synthesis of N-substituted sulfamate esters, unexpected symmetrical sulfite formation was suppressed by changing the tertiary amine. The effect of tertiary amines was proposed using linear regression. Our approach rapidly (≤90 s) provides desired products containing acidic and/or basic labile groups without tedious purification under mild (20 °C) conditions.

Deprotonated sulfamic acid and its homodimers: Does sulfamic acid adopt zwitterion during cluster growth?

We present a joint experimental and computational study on the geometric and electronic structures of deprotonated sulfamic acid (SA) clusters [(SA)n-H]- (n = 1, 2) employing negative ion photoelectron spectroscopy and high-level ab initio calculations. The photoelectron spectra provide the vertical/adiabatic detachment energy (VDE/ADE) of the sulfamate anion (SM-) H2N●SO3- at 4.85 ± 0.05 and 4.58 ± 0.08 eV, respectively, and the VDE and ADE of the SM-●SA dimer at 6.41 ± 0.05 and 5.87 ± 0.08 eV, respectively. The significantly increased electron binding energies of the dimer confirm the enhanced electronic stability upon the addition of one SA molecule. The CCSD(T)-predicted VDEs/ADEs agree excellently with the experimental data, confirming the identified structures as the most stable ones. Two types of dimer isomers possessing different hydrogen bonding (HB) motifs are identified, corresponding to SM- binding to a zwitterionic SA (SM-●SAz) and a canonical SA (SM-●SAc), respectively. Two N-H⋯O HBs and one superior O-H⋯O HB are formed in the lowest-lying SM-●SAc, while SM-●SAz has three moderate N-H⋯O HBs, with the former being 4.71 kcal/mol more stable. Further theoretical analyses reveal that the binding strength advantage of SM-●SAc over SM-●SAz arises from its significant contributions of orbital interactions between fragments, illustrating that sulfamate strongly interacts with its parent SA acid and preferably chooses the canonical SA in the subsequent cluster formations. Given the prominent presence of SA, this study provides the first evidence that the canonical dimer model of sulfamic acid should exist as a superior configuration during cluster growth.

Examining the molecular mechanisms of topiramate in alleviating insulin resistance: A study on C2C12 myocytes and 3T3L-1 adipocytes

PURPOSE

Migraine, a severely debilitating condition, may be effectively managed with topiramate, known for its migraine prevention and weight loss properties due to changes in body muscle and fat composition and improved insulin sensitivity. However, the mechanism of topiramate in modulating insulin response in adipocytes and myocytes remains elusive. This study aims to elucidate these molecular mechanisms, offering insights into its role in weight management for migraine sufferers and underpinning its clinical application.

METHODS

Insulin resistance improvements were evaluated through glucose uptake measurements in C2C12 muscle cells and 3T3L-1 adipocytes, with Oil red O staining conducted on adipocytes. RNA-seq transcriptome analysis was used to identify the regulatory target genes of topiramate in these cells. The involvement of key genes and pathways was further validated through western blot analysis.

RESULTS

Topiramate effectively reduced insulin resistance in C2C12 and 3T3L-1 cells. In C2C12 cells, it significantly lowered SORBS1 gene and protein levels. In 3T3L-1 cells, topiramate upregulated CTGF and downregulated MAPK8 and KPNA1 genes. Changes were notable in nuclear cytoplasmic transport and circadian signaling pathways. Furthermore, it caused downregulation of MKK7, pJNK1/ JNK1, BMAL1, and CLOCK proteins compared to the insulin-resistant model.

CONCLUSION

This study provides preliminary insights into the mechanisms through which topiramate modulates insulin resistance in C2C12 myocytes and 3T3L-1 adipocytes, enhancing our understanding of its therapeutic potential in managing weight and insulin sensitivity in migraine patients.

Sulfilimine bond formation in collagen IV

The collagen IV network plays a crucial role in providing structural support and mechanical integrity to the basement membrane and surrounding tissues. A key aspect of this network is the formation of intra- and inter-collagen fibril crosslinks. One particular crosslink, an inter-residue sulfilimine bond, has been found, so far, to be unique to collagen IV. More specifically, these crosslinks are primarily formed between methionine and lysine or hydroxylysine residues and can occur within a single collagen fibril or between different collagen fibrils. Due to its significance as the major crosslink in the collagen IV network, the sulfilimine bond plays critical roles in tissue development and various human diseases. While the proposed reaction mechanism for sulfilimine bond formation is supported by experimental evidence, the precise nature of this bond remained uncertain until computational studies were conducted. The process involves the reaction of hypohalous acids (e.g., HOBr, HOCl), produced by a peroxidasin enzyme in the basement membrane, with the sidechain sulfur of methionine or sidechain nitrogen of lysine/hydroxylysine residues in collagen IV, to form halosulfonium or haloamine intermediates, respectively. The halosulfonium/haloamine then reacts with the sidechain amine/sulfide of the lysine (or hydroxylysine) or methionine respectively, eventually resulting in the formation of the sulfilimine (MetSNLys/Hyl) crosslink. The sulfilimine product formed not only plays a crucial role in physiological processes but also finds applications in various industrial and pharmaceutical contexts. In this review, we provide a comprehensive summary of existing studies, including our own research, aimed at understanding the reaction mechanism, protonation states, characteristic nature, and dynamic behavior of the sulfilimine bond in collagen IV. The goal is to offer readers an overview of this critically important biochemical bond.

Copper(I)-Photocatalyzed Diastereoselective Aziridination of N-Sulfonyl Imines with Vinyl Azides: Application to Benzo[f][1,2,3]oxathiazepines Dioxides and Fused Isoxazolines

An in situ generated photoactive copper(I)-complex-catalyzed aziridination reaction of cyclic N-sulfonyl imines with α-aryl-substituted vinyl azides irradiated by blue-LEDs light is reported for the first time. This novel SET process represents a mild, sustainable, and pragmatic method for accessing synthetically resourceful sulfamidate-fused aziridines in acceptable chemical yields with excellent diastereoselectivities. Delightedly, pharmacologically attractive benzo[f][1,2,3]oxathiazepine dioxides and fused isoxazoline frameworks were achieved through our newly developed metal-free based ring-expansion techniques, highlighting the synthetic value of accessed aziridines. Finally, the possible mechanism for [2+1] aza-cyclization was presented based on the conduction of a series of control experiments.

[4+2]-Cycloaddition of 2-Aminophenyl Enones with Cyclic N-Sulfimines to Access Enantioenriched Ring-Fused Aminals

Ring-fused aminal is an interesting structural skeleton in biologically active and pharmaceutically relevant compounds. A novel and efficient method for synthesizing benzosulfamidate-fused tetrahydroquinazolines is described. By employing the [4+2]-cycloaddition of 2-aminophenyl enones with cyclic N-sulfimines in the presence of DMAP as a base, the desired benzosulfamidate-fused tetrahydroquinazolines were obtained in good yields with high diastereoselectivities. Furthermore, an organocatalytic asymmetric [4+2]-cycloaddition was successfully achieved using a squaramide-based catalyst, enabling the enantioselective synthesis of chiral ring-fused tetrahydroquinazolines with high yields and enantio- as well as diastereoselectivities (up to 89 % yield, 94 % ee, and >30 : 1 dr).

Palladium-catalyzed [4 + 2] cycloaddition of 2-methylidenetrimethylene carbonate or methylene cyclic carbamate with sulfamate-derived cyclic imines

A palladium-catalyzed [4 + 2] cycloaddition of 2-methylidenetrimethylene carbonate or methylene cyclic carbamate with sulfamate-derived cyclic imines has been successfully developed under mild reaction conditions, affording pharmacologically interesting oxazine or hydropyrimidine derivatives in high yields (up to 99% yield). Furthermore, the cycloaddition reactions could be efficiently scaled up and several synthetic transformations were accomplished for the construction of other useful 1,3-oxazine and hydropyrimidinone derivatives.

Description of Chemical Synthesis, Nuclear Magnetic Resonance Characterization and Biological Activity of Estrane-Based Inhibitors/Activators of Steroidogenesis

Steroid hormones play a crucial role in several aspects of human life, and steroidogenesis is the process by which hormones are produced from cholesterol using several enzymes that work in concert to obtain the appropriate levels of each hormone at the right time. Unfortunately, many diseases, such as cancer, endometriosis, and osteoporosis as examples, are caused by an increase in the production of certain hormones. For these diseases, the use of an inhibitor to block the activity of an enzyme and, in doing so, the production of a key hormone is a proven therapeutic strategy whose development continues. This account-type article focuses on seven inhibitors (compounds 1-7) and an activator (compound 8) of six enzymes involved in steroidogenesis, namely steroid sulfatase, aldo-keto reductase 1C3, types 1, 2, 3, and 12 of the 17β-hydroxysteroid dehydrogenases. For these steroid derivatives, three topics will be addressed: (1) Their chemical synthesis from the same starting material, estrone, (2) their structural characterization using nuclear magnetic resonance, and (3) their in vitro or in vivo biological activities. These bioactive molecules constitute potential therapeutic or mechanistic tools that could be used to better understand the role of certain hormones in steroidogenesis.

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.

Sulfamate Acetamides as Self-Immolative Electrophiles for Covalent Ligand-Directed Release Chemistry

Electrophiles for covalent inhibitors that are suitable for in vivo administration are rare. While acrylamides are prevalent in FDA-approved covalent drugs, chloroacetamides are considered too reactive for such purposes. We report sulfamate-based electrophiles that maintain chloroacetamide-like geometry with tunable reactivity. In the context of the BTK inhibitor ibrutinib, sulfamate analogues showed low reactivity with comparable potency in protein labeling, in vitro, and cellular kinase activity assays and were effective in a mouse model of CLL. In a second example, we converted a chloroacetamide Pin1 inhibitor to a potent and selective sulfamate acetamide with improved buffer stability. Finally, we show that sulfamate acetamides can be used for covalent ligand-directed release (CoLDR) chemistry, both for the generation of "turn-on" probes as well as for traceless ligand-directed site-specific labeling of proteins. Taken together, this chemistry represents a promising addition to the list of electrophiles suitable for in vivo covalent targeting.

New alkaline-earth amidosulfates and their unexpected decomposition to S4N4

The amidosulphates Mg(NH₂SO₃)₂·4H₂O (P2₁/c), Mg(NH₂SO₃)₂·3H₂O (P1̄), Ca(NH₂SO₃)₂·4H₂O (C2/c), Ca(NH₂SO₃)₂·H₂O (P2₁2₁2₁), Sr(NH₂SO₃)₂·4H₂O (C2/c), Sr(NH₂SO₃)₂·H₂O (P2₁/c) and Ba(NH₂SO₃)₂ (Pna2₁) could be obtained as cm-sized crystals from aqueous solutions of the corresponding metal carbonates, hydroxides and amidosulphonic acid, respectively, by careful control of the crystallisation conditions. β-Sr(NH₂SO₃)₂ (Pc) and α-Sr(NH₂SO₃)₂ (P2₁) could be obtained by careful thermal dehydration of Sr(NH₂SO₃)₂·H₂O. Their crystal structures were determined by single-crystal XRD and revealed a rich structural diversity with a significant tendency to form non-centrosymmetric crystals. The compounds were characterised by powder XRD, FT-IR, Raman and UV/vis spectroscopy and thermogravimetry. Temperature programmed single-crystal XRD, powder XRD and Raman spectroscopy, as well as DFT calculations were employed to aid the interpretation of vibrational and thermal properties. For the first time, SHG measurements were performed on metal amidosulphates, revealing the SHG intensities of β-Sr(NH₂SO₃)₂ and Ba(NH₂SO₃)₂ that were comparable to quartz and KDP. Thermal decomposition was additionally studied by the preparation of reaction intermediates, serendipitously revealing the formation of S₄N₄ as the decomposition product. This unprecedented reaction represents the first sulphur nitride synthesis process that neither employs a sulphur halide nor elemental sulphur.

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.

The importance of sulfur-containing motifs in drug design and discovery

INTRODUCTION

Sulfur-containing functional groups are privileged motifs that occur in various pharmacologically effective substances and several natural products. Various functionalities are found with a sulfur atom at diverse oxidation states, as illustrated by thioether, sulfoxide, sulfone, sulfonamide, sulfamate, and sulfamide functions. They are valuable scaffolds in the field of medicinal chemistry and are part of a large array of approved drugs and clinical candidates.

AREA COVERED

Herein, the authors review the current research on the development of organosulfur-based drug discovery. This article also covers details of their roles in the new lead compounds reported in the literature over the past five years 2017-2021.

EXPERT OPINION

Given its prominent role in medicinal chemistry and its importance in drug discovery, sulfur has attracted continuing interest and has been used in the design of various valuable compounds that demonstrate a variety of biological and pharmacological feature activities. Overall, sulfur's role in medicinal chemistry continues to grow. However, many sulfur functionalities remain underused in small-molecule drug discovery and deserve special attention in the armamentarium for treating diverse diseases. Research efforts are also still required for the development of a synthetic methodology for direct access to these functions and late-stage functionalization.

Pd-catalyzed [3 + 2] cycloaddition of cyclic ketimines and trimethylenemethanes toward N-fused pyrrolidines bearing a quaternary carbon

A Pd-catalyzed [3 + 2] cycloaddition of N-sulfonyl cyclic ketimines and trimethylenemethanes (TMM) was developed that afforded N-fused pyrrolidines bearing a quaternary carbon. Under mild reaction conditions, structurally diverse N-sulfonyl cyclic imines, including sulfamate-fused aldimines, aryl- or styryl-substituted sulfamate-derived ketimines, and N-sulfonyl cyclic ketimines, were tolerated as reactants, affording N-fused pyrrolidines with high efficiency.

A facile route to access N-fused pyrrolidines bearing a quaternary carbon from N-sulfonyl ketimines and commercially available trimethylenemethanes has been developed.

Discovery of urease inhibitory effect of sulfamate derivatives: Biological and computational studies

The discovery of life-changing medicines continues to be the driving force for the rapid exploration and expansion of chemical space, enabling access to innovative small molecules of medicinal importance. These small molecules remain the backbone for modern drug discovery. In this context, the treatment of ureolytic bacterial infections inspires the identification of potent and effective inhibitors of urease, a promising and highly needed target for H. pylori eradication. The present study explores the evaluation of sulfamate derivatives for the inhibition of urease enzyme. The tested compounds showed remarkable inhibitory effect and high level of potency. Compound 1q emerged as the lead inhibitor with an IC₅₀ value of 0.062 ± 0.001 µM, ∼360-fold more potent than thiourea (IC₅₀ = 22.31 ± 0.031 µM). The assessment of various contributing factors towards the inhibition profile allowed for the establishment of diverse structure-activity relationships. Kinetics studies revealed the competitive mode of inhibition of compound 1q while molecular modeling analysis identified various crucial binding interactions with ARG609, ARG439, HIS519, HIS492, HIS593, ALA440, and ALA636 in the active pocket of the enzyme. Finally, the calculated pharmacokinetic properties suggest a promising profile of our potent sulfamate-based urease inhibitors.

Discovery of TAK-981, a First-in-Class Inhibitor of SUMO-Activating Enzyme for the Treatment of Cancer

SUMOylation is a reversible post-translational modification that regulates protein function through covalent attachment of small ubiquitin-like modifier (SUMO) proteins. The process of SUMOylating proteins involves an enzymatic cascade, the first step of which entails the activation of a SUMO protein through an ATP-dependent process catalyzed by SUMO-activating enzyme (SAE). Here, we describe the identification of TAK-981, a mechanism-based inhibitor of SAE which forms a SUMO-TAK-981 adduct as the inhibitory species within the enzyme catalytic site. Optimization of selectivity against related enzymes as well as enhancement of mean residence time of the adduct were critical to the identification of compounds with potent cellular pathway inhibition and ultimately a prolonged pharmacodynamic effect and efficacy in preclinical tumor models, culminating in the identification of the clinical molecule TAK-981.

Development and Validation of High-Throughput Bioanalytical Liquid Chromatography-Tandem Mass Spectrometry (LC-MS/MS) Method for the Quantification of Newly Synthesized Antitumor Carbonic Anhydrase Inhibitors in Human Plasma

In the present study, a sensitive and fully validated bioanalytical high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed for the quantitative determination of three newly synthesized carbonic anhydrases inhibitors (CAIs) with potential antitumor activity in human plasma. The analytes and the internal standard (IS) were extracted using 1.5 mL acetonitrile from only 450 µL aliquots of human plasma to achieve the desired protein precipitation. Chromatographic separations were achieved on Phenomenex Kinetex^® C₁₈ column (100 × 4.6 mm, 2.6 µm) using a binary gradient elution mode with a run time of less than 6 min. The mobile phase consisted of solvent (A): 0.1% formic acid in 50% methanol and solvent B: 0.1% formic acid in acetonitrile (30:70, v/v), pumped at a flow rate of 0.8 mL/min. Detection was employed using triple quadrupole tandem mass spectrometer (API 3500) equipped with an electrospray ionization (ESI) source in the positive ion mode. Multiple reaction monitoring (MRM) mode was selected for quantitation through monitoring the precursor-to-parent ion transition at m/z 291.9 → 173.0, m/z 396.9 → 225.1, m/z 388.9 → 217.0, and m/z 146.9 → 91.0 for AW-9a, WES-1, WES-2, and Coumarin (IS), respectively. Linearity was computed using the weighted least-squares linear regression method (1/x²) over a concentration range of 1–1000, 2.5–800, and 5–500 ng/mL for AW-9a, WES-1, and WES-2; respectively. The bioanalytical LC-MS/MS method was fully validated as per U.S. Food and Drug Administration (FDA) guidelines with all respect to linearity, accuracy, precision, carry-over, selectivity, dilution integrity, and stability. The proposed LC-MS/MS method was applied successfully for the determination of all investigated drugs in spiked human plasma with no significant matrix effect, which is a crucial cornerstone in further therapeutic drug monitoring of newly developed therapeutic agents.

Novel 3-substituted coumarins as selective human carbonic anhydrase IX and XII inhibitors: Synthesis, biological and molecular dynamics analysis

In this study, diverse series of coumarin derivatives were developed as potential carbonic anhydrase inhibitors (CAIs). A "tail" approach was adopted by selecting the coumarin motif as a tail that is connected to the ZBG benzenesulfonamide moiety via a hydrazine (4a,b) or hydrazide (5a,b) linker. Thereafter, an aryl sulfone tail was incorporated to afford the dual tailed coumarin-sulfonamide arylsulfonehydrazones (13a-d) and hydrazides (14a,b). Then, the ZBG were removed from compounds 13 and 14 to furnish coumarin arylsulfonehydrazones (11a-d) and hydrazides (12a,b). Coumarin-sulfonamides 4 and 5 emerged as non-selective CAIs as they displayed good inhibitory activities toward all the examined CA isozymes (I, II, IX and XII) in the nanomolar ranges. Interestingly, the "dual-tail" approach (compounds 13 and 14) succeeded in achieving a good activity and selectivity toward CA IX/XII over the physiologically dominant CA I/II. In particular, compounds 13d and 14a were the most selective coumarin-sulfonamide counterparts. Concerning non-sulfonamide coumarin derivatives, coumarins 8 exhibited excellent activity and selectivity profiles against the target hCA IX/XII, whereas, coumarins 11 and 12 reported excellent selectivity profile, but they barely inhibited hCA IX/XII with K_Is spanning in the micromolar ranges. Furthermore, molecular modelling studies were applied to get a deep focus about the feasible affinities and binding interactions for target coumarin-sulfonamides 4, 5, 13 and 14 with the active site for CA II, IX and XII isoforms.

SuFEx Activation with Ca(NTf2)2: A Unified Strategy to Access Sulfamides, Sulfamates, and Sulfonamides from S(VI) Fluorides

A method to activate sulfamoyl fluorides, fluorosulfates, and sulfonyl fluorides with calcium triflimide and DABCO for SuFEx with amines is described. The reaction was applied to a diverse set of sulfamides, sulfamates, and sulfonamides at room temperature under mild conditions. Additionally, we highlight this transformation to parallel medicinal chemistry to generate a broad array of nitrogen-based S(VI) compounds.

Balanced polarizable Drude force field parameters for molecular anions: phosphates, sulfates, sulfamates, and oxides

Polarizable force fields are emerging as a more accurate alternative to additive force fields in terms of modeling and simulations of a variety of chemicals including biomolecules. Explicit treatment of induced polarization in charged species such as phosphates and sulfates offers the potential for achieving an improved atomistic understanding of the physical forces driving their interactions with their environments. To help achieve this, in this study we present balanced Drude polarizable force field parameters for molecular ions including phosphates, sulfates, sulfamates, and oxides. Better balance was primarily achieved in the relative values of minimum interaction energies and distances of the anionic model compounds with water at the Drude and quantum mechanical (QM) model chemistries. Parametrization involved reoptimizing available parameters as well as extending the force field to new molecules with the goal of achieving self-consistency with respect to the Lennard-Jones and electrostatic parameters targeting QM and experimental hydration free energies. The resulting force field parameters achieve consistent treatment across the studied anions, facilitating more balanced simulations of biomolecules and small organic molecules in the context of the classical Drude polarizable force field. Graphical abstract.

Under the radar - Exceptionally high environmental concentrations of the high production volume chemical sulfamic acid in the urban water cycle

Elevated concentrations of sulfamate, the anion of sulfamic acid, were found in surface waters and finished drinking water in Germany with concentrations up to 580 μg/L and 140 μg/L, respectively. Wastewater treatment plant (WWTP) effluent was identified as the dominant source of sulfamate in the urban water cycle, as sulfamate concentrations correlated positively (0.77 > r < 0.99) with concentrations of the wastewater tracer carbamazepine in samples from different waterbodies. Ozonation and activated sludge experiments proved that sulfamate can be formed from chemical and biological degradation of various precursors. Molar sulfamate yields were highly compound-specific and ranged from 2% to 56%. However, the transformation of precursors to sulfamate in WWTPs and wastewater-impacted waterbodies was found to be quantitatively irrelevant, since concentrations of sulfamate in these compartments are already high, presumably due to its primary use as an acidic cleaning agent. Sulfamate concentrations in the influent and effluent of studied WWTPs ranged from 520 μg/L to 1900 μg/L and from 490 μg/L to 1600 μg/L, respectively. Laboratory batch experiments were performed to assess the recalcitrance of sulfamate for chemical oxidation. In combination with the results from sampling conducted at full-scale waterworks, it was shown that common drinking water treatment techniques, including ozonation and filtration with activated carbon, are not capable to remove sulfamate. The results of biodegradation tests and from the analysis of samples taken at four bank filtration sites indicate that sulfamate is attenuated in the sediment/water interface of aquatic systems and during aquifer passage under aerobic and anaerobic conditions. Sulfamate concentrations decreased by between 62% and 99% during aquifer passage at the bank filtration sites. Considering the few data on short term ecotoxicity, about 30% of the presented sulfamate levels in ground and surface water samples did exceed the predicted no-effect concentration (PNEC) of sulfamate, and thus effects of sulfamate on the aquatic ecosystem of wastewater-impacted waterbodies in Germany cannot be excluded so far. Toxicological estimations suggest that no risk to human health is expected by concentrations of sulfamate typically encountered in tap water.

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.

Catalytic Sulfamoylation of Alcohols with Activated Aryl Sulfamates

We report a new catalytic method for alcohol sulfamoylation that deploys electron-deficient aryl sulfamates as activated group transfer reagents. The reaction utilizes the simple organic base N-methylimidazole, proceeds under mild conditions, and provides intrinsic selectivity for 1° over 2° alcohols (up to >40:1 for certain nucleosides). The requisite aryl sulfamate donors are stable crystalline solids that can be readily prepared on a large scale. Mechanistic considerations support the intermediacy of HNSO₂ "aza-sulfene" in the transfer reaction.

On the scope of SuFEx as a bioorthogonal click process

Coupling of sulfonyl fluorides, fluorosulfates and iminosulfur oxydifluorides with proteins gave the corresponding sulfonamide, sulfamate and sulfamide adducts under mild conditions.

Asymmetric Total Synthesis Enables Discovery of Antibacterial Activity of Siladenoserinols A and H

Siladenoserinols A and H were found to show moderate inhibitory activity toward p53-Hdm2 interactions. Our total synthesis allowed us to further examine their bioactivities, which revealed that (i) siladenoserinols A and H were not cytotoxic against cancer cell lines and (ii) siladenoserinol A and its desulfamate analogue exhibited significant antibacterial activity against Gram-positive bacteria including MRSA. Our studies demonstrate that siladenoserinols are a promising new class of bactericidal Gram-positive antibiotics without hemolytic activity.

Structure-activity relationship with pyrazoline-based aromatic sulfamates as carbonic anhydrase isoforms I, II, IX and XII inhibitors: Synthesis and biological evaluation

Four new series of aromatic sulfamates were synthesized and investigated for the inhibition of four human (h) isoforms of zinc enzyme carbonic anhydrase (CA, EC 4.2.1.1), hCA I, II, IX, and XII. The reported derivatives, obtained by a sulfamoylation reaction of the corresponding phenolic precursors, bear 3,5-diarylpyrazoline moieties as spacers between the benzenesulfamate fragment which binds the zinc ion from the active site, and the tail of the inhibitor. Pyrazolines are biologically privileged scaffolds, endowed with versatile biological activity, such as an anti-proliferative action. The derivatives were tested for the inhibition of the cytosolic, hCA I and II (off target isoforms) and the trans-membrane, tumor-associated hCA IX and XII enzymes (anticancer drug targets). Generally, hCA I was not effectively inhibited, whereas many low nanomolar inhibitors were evidenced against hCA II (KIs in the range of 0.42-90.1 nM), IX (KIs in the range of 0.72-63.6 nM), and XII (KIs in the range of 0.88-85.2 nM). The best substitution fragments at the pyrazoline ring included for CA II a 4-sulfamic group on the 3-aryl and halogens on the 5-aryl or a methoxy group on the 3-aryl and a 4-sulfamate group on the 5-aryl; for CA IX and CA XII they included the sulfamic group on the 3- or 4-position of the 5-aryl and an electronwithdrawing group on the 4-postion of the 3-aryl ring.

Naphthalimide-Based Template for Inhibitor Screening via Cross-Linking and In-Gel Fluorescence: A Case Study against HCA II

We describe a rapid electrophoresis-based method for profiling of carbonic anhydrase inhibitors. In addition to the pharmacophore moiety intended for reversible interaction with a target enzyme, a fluorescent template with a built-in azide group for photoaffinity labeling is also included as a part of the inhibitor design. Following incubation and irradiation, gel electrophoresis with visualization under UV allows assessment of the efficiency of cross-linking. The relative efficiency of cross-linking of various probes can be regarded as a reflection of their inhibition potencies, an assumption supported by the trend in their IC₅₀/K _i values. The method has the advantage of being applicable to impure enzyme preparations and also can be used to screen several inhibitors including their promiscuity in parallel in a short time as has been currently demonstrated with HCA II.

An Apparent Binary Choice in Biochemistry: Mutual Reactivity Implies Life Chooses Thiols or Nitrogen-Sulfur Bonds, but Not Both

A fundamental goal of biology is to understand the rules behind life's use of chemical space. Established work focuses on why life uses the chemistry that it does. Given the enormous scope of possible chemical space, we postulate that it is equally important to ask why life largely avoids certain areas of chemical space. The nitrogen-sulfur bond is a prime example, as it rarely appears in natural molecules, despite the very rich N-S bond chemistry applied in various branches of industry (e.g., industrial materials, agrochemicals, pharmaceuticals). We find that, out of more than 200,000 known, unique compounds made by life, only about 100 contain N-S bonds. Furthermore, the limited number of N-S bond-containing molecules that life produces appears to fall into a few very distinctive structural groups. One may think that industrial processes are unrelated to biochemistry because of a greater possibility of solvents, catalysts, and temperatures available to industry than to the cellular environment. However, the fact that life does rarely make N-S bonds, from the plentiful precursors available, and has evolved the ability to do so independently several times, suggests that the restriction on life's use of N-S chemistry is not in its synthesis. We present a hypothesis to explain life's extremely limited usage of the N-S bond: that the N-S bond chemistry is incompatible with essential segments of biochemistry, specifically with thiols. We support our hypothesis by (1) a quantitative analysis of the occurrence of N-S bond-containing natural products and (2) reactivity experiments between selected N-S compounds and key biological molecules. This work provides an example of a reason why life nearly excludes a distinct region of chemical space. Combined with future examples, this potentially new field of research may provide fresh insight into life's evolution through chemical space and its origin and early evolution.

Organocatalytic enantioselective functionalization of indoles in the carbocyclic ring with cyclic imines

An organocatalytic enantioselective functionalization in the carbocyclic ring of indoles with benzoxathiazine 2,2-dioxides is described using a quinine-derived bifunctional organocatalyst.

Chemoselective cyclization of N-sulfonyl ketimines with ethenesulfonyl fluorides: access to trans-cyclopropanes and fused-dihydropyrroles

A stereo- and chemoselective ring closing reaction of N-sulfonyl ketimines with ethene sulfonyl fluorides promoted by DBU is reported. This selective C–C vs. C–N bond cyclization process delivers to trans-cyclopropanes (dr up to ≤99 : 1) and fused-dihydropyrroles.

Natural Products Containing a Nitrogen-Sulfur Bond

Only about 100 natural products are known to contain a nitrogen-sulfur (N-S) bond. This review thoroughly categorizes N-S bond-containing compounds by structural class. Information on biological source, biological activity, and biosynthesis is included, if known. We also review the role of N-S bond functional groups as post-translational modifications of amino acids in proteins and peptides, emphasizing their role in the metabolism of the cell.

Pd-catalyzed [3 + 2] cycloaddition of vinylcyclopropanes with 1-azadienes: synthesis of 4-cyclopentylbenzo[e][1,2,3]oxathiazine 2,2-dioxides

The palladium-catalyzed [3 + 2] cycloaddition of vinylcyclopropanes and 1-azadienes has been developed under mild reaction conditions, giving the multisubstituted cyclopentane derivatives in good to excellent yields with moderate to good diastereoselectivities. The relative configuration of both diastereomers of the products have been determined through X-ray crystallographic diffraction.

Pd-catalyzed [3 + 2] cycloaddition of vinylcyclopropanes with 1-azadienes gave highly functionalized cyclopentane derivatives in high yields.

Cyclic imines – preparation and application in synthesis

Cyclic imines, available from various nitrogen-containing reactants, serve as versatile synthetic intermediates for biologically active compounds.

Pd-Catalyzed diastereoselective [3 + 2] cycloaddition of vinylcyclopropanes with sulfamate-derived cyclic imines

The palladium-catalyzed diastereoselective [3 + 2] cycloaddition reaction of vinylcyclopropanes with sulfamate-derived cyclic imines worked efficiently under mild conditions, providing sulfamate-fused pyrrolidines in good to excellent yields.