Sulfamic Acid and Its N- and O-Substituted Derivatives

Sulfamoyl nitrenes: singlet or triplet ground state?

Two prototypical sulfamoyl nitrenes R₂NS(O)₂–N (R = H and Me) in the triplet state were generated via the closed-shell singlet state by passing a low-energy minimum energy crossing point (MECP).

Synthesis of N-Substituted Sulfamate Esters from Sulfamic Acid Salts by Activation with Triphenylphosphine Ditriflate

A general approach to access sulfamate esters through preparation of sulfamic acid salts, subsequent activation with triphenylphosphine ditriflate, and nucleophilic trapping is disclosed. The method proceeds in modest to excellent yields to incorporate nucleophiles derived from aliphatic alcohols and phenols. This approach can be employed to furnish differentially substituted sulfamides.

A QSTR-Based Expert System to Predict Sweetness of Molecules

This work describes a novel approach based on advanced molecular similarity to predict the sweetness of chemicals. The proposed Quantitative Structure-Taste Relationship (QSTR) model is an expert system developed keeping in mind the five principles defined by the Organization for Economic Co-operation and Development (OECD) for the validation of (Q)SARs. The 649 sweet and non-sweet molecules were described by both conformation-independent extended-connectivity fingerprints (ECFPs) and molecular descriptors. In particular, the molecular similarity in the ECFPs space showed a clear association with molecular taste and it was exploited for model development. Molecules laying in the subspaces where the taste assignation was more difficult were modeled trough a consensus between linear and local approaches (Partial Least Squares-Discriminant Analysis and N-nearest-neighbor classifier). The expert system, which was thoroughly validated through a Monte Carlo procedure and an external set, gave satisfactory results in comparison with the state-of-the-art models. Moreover, the QSTR model can be leveraged into a greater understanding of the relationship between molecular structure and sweetness, and into the design of novel sweeteners.

Sulfamide chemistry applied to the functionalization of self-assembled monolayers on gold surfaces

Aniline-terminated self-assembled monolayers (SAMs) on gold surfaces have successfully reacted with ArSO₂NHOSO₂Ar (Ar = 4-MeC₆H₄ or 4-FC₆H₄) resulting in monolayers with sulfamide moieties and different end groups. Moreover, the sulfamide groups on the SAMs can be hydrolyzed showing the partial regeneration of the aniline surface. SAMs were characterized by water contact angle (WCA) measurements, Fourier-transform infrared reflection absorption spectroscopy (IRRAS) and X-ray photoelectron spectroscopy (XPS).

New metal extractants and super-acidic ionic liquids derived from sulfamic acid

N-Alkylated sulfamic acid derivatives are very interesting for metal processing. A new class of metal extractants and super-acidic ionic liquids is introduced.

Discovery and Development of the Aryl O-Sulfamate Pharmacophore for Oncology and Women's Health

In 1994, following work from this laboratory, it was reported that estrone-3-O-sulfamate irreversibly inhibits a new potential hormone-dependent cancer target steroid sulfatase (STS). Subsequent drug discovery projects were initiated to develop the core aryl O-sulfamate pharmacophore that, over some 20 years, have led to steroidal and nonsteroidal drugs in numerous preclinical and clinical trials, with promising results in oncology and women's health, including endometriosis. Drugs have been designed to inhibit STS, e.g., Irosustat, as innovative dual-targeting aromatase-steroid sulfatase inhibitors (DASIs) and as multitargeting agents for hormone-independent tumors, such as the steroidal STX140 and nonsteroidal counterparts, acting inter alia through microtubule disruption. The aryl sulfamate pharmacophore is highly versatile, operating via three distinct mechanisms of action, and imbues attractive pharmaceutical properties. This Perspective gives a personal view of the work leading both to the therapeutic concepts and these drugs, their current status, and how they might develop in the future.

Estrogen O-sulfamates and their analogues: Clinical steroid sulfatase inhibitors with broad potential

Estrogen sulfamate derivatives were the first irreversible active-site-directed inhibitors of steroid sulfatase (STS), an emerging drug target for endocrine therapy of hormone dependent diseases that catalyzes inter alia the hydrolysis of estrone sulfate to estrone. In recent years this has stimulated clinical investigation of the estradiol derivative both as an oral prodrug and its currently ongoing exploration in endometriosis. 2-Substituted steroid sulfamate derivatives show considerable potential as multi-targeting agents for hormone-independent disease, but are also potent STS inhibitors. The steroidal template has spawned nonsteroidal STS inhibitors one of which, Irosustat, has been evaluated clinically in breast cancer, endometrial cancer and prostate cancer and there is potential for innovative dual-targeting approaches. This review surveys the role of estrogen sulfamates, their analogues and current status.

Natural Product Primary Sulfonamides and Primary Sulfamates

Primary sulfonamide and primary sulfamate functional groups feature prominently in the structures of U.S. FDA-approved drugs. However, the natural product chemical space contains few examples of these well-known zinc-binding chemotypes, with just two primary sulfonamide and five primary sulfamate natural products isolated and characterized to date. One of these natural products was isolated from a marine sponge, with the remainder isolated from Streptomyces species. In this review are outlined for the first time the discovery, isolation, striking breadth of bioactivity, and total synthesis (where available) for this rare group of natural products.

Structural insights into carbonic anhydrase IX isoform specificity of carbohydrate-based sulfamates

Carbonic anhydrase IX (CA IX) is an extracellular transmembrane homodimeric zinc metalloenzyme that has been validated as a prognostic marker and therapeutic target for several types of aggressive cancers. CA IX shares a close homology with other CA isoforms, making the design of CA IX isoform selective inhibitors challenging. In this paper, we describe the development of a new class of CA IX inhibitors that comprise a sulfamate as the zinc binding group, a variable linker, and a carbohydrate “tail” moiety. Seven compounds inhibited CA IX with low nM K_i values of 1–2 nM and also exhibited permeability profiles to preferentially target the binding of extracellular CA IX over cytosolic CAs. The crystal structures of two of these compounds in complex with a CA IX-mimic (a variant of CA II, with active site residues that mimic CA IX) and one compound in complex with CA II have been determined to 1.7 Å resolution or better and demonstrate a selective mechanism of binding between the hydrophilic and hydrophobic pockets of CA IX versus CA II. These compounds present promising candidates for anti-CA IX drugs and the treatment for several aggressive cancer types.

Sulfur(VI) fluoride exchange (SuFEx): another good reaction for click chemistry

Aryl sulfonyl chlorides (e.g. Ts-Cl) are beloved of organic chemists as the most commonly used S(VI) electrophiles, and the parent sulfuryl chloride, O2 S(VI) Cl2 , has also been relied on to create sulfates and sulfamides. However, the desired halide substitution event is often defeated by destruction of the sulfur electrophile because the S(VI) Cl bond is exceedingly sensitive to reductive collapse yielding S(IV) species and Cl(-) . Fortunately, the use of sulfur(VI) fluorides (e.g., R-SO2 -F and SO2 F2 ) leaves only the substitution pathway open. As with most of click chemistry, many essential features of sulfur(VI) fluoride reactivity were discovered long ago in Germany.6a Surprisingly, this extraordinary work faded from view rather abruptly in the mid-20th century. Here we seek to revive it, along with John Hyatt's unnoticed 1979 full paper exposition on CH2 CH-SO2 -F, the most perfect Michael acceptor ever found.98 To this history we add several new observations, including that the otherwise very stable gas SO2 F2 has excellent reactivity under the right circumstances. We also show that proton or silicon centers can activate the exchange of SF bonds for SO bonds to make functional products, and that the sulfate connector is surprisingly stable toward hydrolysis. Applications of this controllable ligation chemistry to small molecules, polymers, and biomolecules are discussed.