SNAr or Sulfonylation? Chemoselective Amination of Halo(het)arene Sulfonyl Halides for Synthetic Applications and Ultralarge Compound Library Design.

The chemoselectivity of halo(het)arene sulfonyl halide aminations is studied thoroughly under parallel synthesis conditions, and the scope and limitations of the method are established. It is shown that SNAr-reactive sulfonyl halides typically undergo sulfonamide synthesis during the first step; the second amination is also possible provided that the SNAr-active center is sufficiently reactive. On the contrary, sulfonyl fluorides bearing an arylating moiety undergo selective transformation at the latter reactive center under proper control. Further sulfur-fluoride exchange (SuFEx) is also possible, which can be especially valuable for some sulfonyl halide classes. The developed two-step parallel double amination protocol provides access to a 6.67-billion compound synthetically tractable REAL-type chemical space (76% expected synthesis success rate).

Synthesis of α-C-Stereochemically Pure Secondary Sulfonamides.

A convenient "green" stereoretentive approach to sp3-enriched secondary sulfonamides bearing an asymmetric center at the α position to the sulfur atom is described. The method relies on the electrophilic amination of the corresponding stereochemically pure sulfinates with N-alkylhydroxylamine sulfonic acids (in turn easily prepared from N-alkylhydroxylamine and HSO3Cl). It is shown that the efficiency of the approach is governed mainly by steric factors; its tolerance to several functional groups (e.g., ether, phthalimide, or N-Boc carbamate) is also demonstrated.

Large-Scale Synthesis and Modifications of Bicyclo[1.1.1]pentane-1,3-dicarboxylic Acid (BCP).

In flow photochemical addition of propellane to diacetyl allowed construction of the bicyclo[1.1.1]pentane (BCP) core in a 1 kg scale within 1 day. Haloform reaction of the formed diketone in batch afforded bicyclo[1.1.1]pentane-1,3-dicarboxylic acid in a multigram amount. Representative gram scale transformations of the diacid were also performed to obtain various BCP-containing building blocks-alcohols, acids, amines, trifluoroborates, amino acids, etc.-for medicinal chemistry.

Synthesis of spirocyclic ß- and γ-sultams by one-pot reductive cyclization of cyanoalkylsulfonyl fluorides.

One-pot intramolecular cyclization of novel sp3-enriched cyanoalkylsulfonyl fluorides into spirocyclic ß- or γ-sultams is disclosed. The method relies on nitrile group reduction followed by sulfonylation of amino group thus formed upon mild conditions (NaBH4, NiCl2·6H2O in MeOH). Cyclization proceeds smoothly with considerable efficiency (48-84%, 10 examples) on up to 30 g scale. The cyanoalkylsulfonyl fluoride intermediates can be obtained via S-nucleophilic substitution in ß-functionalized alkanenitriles or double alkylation of α-alkylthioacetonitrile, followed by oxidative chlorination with Cl2 and further reaction with KHF2. The title mono- and bifunctional sultams are advanced sp3-enriched building blocks for drug discovery and organic synthesis providing novel substitution patterns and frameworks mimicking saturated nitrogen heterocycles such as pyrrolidine/pyrrolidone.

Twisting and Turning the Sulfonamide Bond: A Synthetic, Quantum Chemical, and Crystallographic Study.

Structural restriction of the sulfonamide bond was used to design sultams with abnormal geometric parameters. Based on analysis of tertiary aliphatic sulfonamides published in the Cambridge crystallographic database, Paquette's sultams (i.e., bridged bicyclic sultams with a bridgehead nitrogen atom) were outlined, and a number of these compounds (including the novel smallest representative, 2-thia-1-azabicyclo[2.1.1]hexane 2,2-dioxide) were synthesized by cyclization of the corresponding amino sulfonyl fluorides. A series of tertiary aliphatic sulfonamides was studied by crystallographic and quantum chemical methods. It was found that the s-character of the nitrogen lone pair is the most important factor defining properties of the S-N bond. Thus, going from the sp3-hybrid lone pair in common sulfonamides to the sp-like lone pair in the smallest Paquette's sultam resulted in an increase in S-N bond length by ca. 0.06 Å. The strain energy of ca. 30 kcal/mol was predicted for the latter compound, which was higher than for any existing sulfonamides studied.

Sulfonimidamides and Imidosulfuric Diamides: Compounds from an Underexplored Part of Biologically Relevant Chemical Space.

Two novel solid reagents-1-sulfonimidoyl- and 1-sulfamimidoyl-3-methylimidazolium derivatives-for the synthesis of sulfonimidamides and imidosulfuric diamides, respectively, were developed. It is shown that these reagents are very effective in substitution reactions with various N- and O-nucleophiles; therefore, they significantly extend the accessibility to the chemical space covered by organosulfur(VI) compounds with S=N bonds. In addition, previously unknown imidosulfuric diamides with free imino nitrogen groups were prepared, and their physical and chemical properties were characterized (including molecular geometry, pKa , Log P, microsomal stability, and reactivity towards typical electrophiles). Similar to other organosulfur(VI) derivatives with S=N bonds, these compounds can be considered as promising bioisosteres of amides, ureas, or sulfonamides.

Direct mapping of ligandable tyrosines and lysines in cells with chiral sulfonyl fluoride probes.

Advances in chemoproteomic technology have revealed covalent interactions between small molecules and protein nucleophiles, primarily cysteine, on a proteome-wide scale. Most chemoproteomic screening approaches are indirect, relying on competition between electrophilic fragments and a minimalist electrophilic probe with inherently limited proteome coverage. Here we develop a chemoproteomic platform for direct electrophile-site identification based on enantiomeric pairs of clickable arylsulfonyl fluoride probes. Using stereoselective site modification as a proxy for ligandability in intact cells, we identify 634 tyrosines and lysines within functionally diverse protein sites, liganded by structurally diverse probes. Among multiple validated sites, we discover a chiral probe that modifies Y228 in the MYC binding site of the epigenetic regulator WDR5, as revealed by a high-resolution crystal structure. A distinct chiral probe stimulates tumour cell phagocytosis by covalently modifying Y387 in the recently discovered immuno-oncology target APMAP. Our work provides a deep resource of ligandable tyrosines and lysines for the development of covalent chemical probes.