Flexible C2-Symmetric Bis-Sulfoxides as Ligands in Enantioselective 1,4-Addition of Boronic Acids to Electron-Deficient Alkenes

Asymmetric Total Synthesis of Hasubanan Alkaloids: Periglaucines A-C, N,O-Dimethyloxostephine and Oxostephabenine

We report herein the asymmetric total synthesis of periglaucines A-C, N,O-dimethyloxostephine and oxostephabenine. The key strategies used include: 1) a Rh^I -catalyzed regio- and diastereoselective Hayashi-Miyaura reaction to connect two necessary fragments; 2) an intramolecular photoenolization/Diels-Alder (PEDA) reaction to construct the highly functionalized tricyclic core skeleton bearing a quaternary center; 3) a bio-inspired intramolecular Michael addition and transannular acetalization to generate the aza[4.4.3]propellane and the tetrahydrofuran ring.

Enantiopure ferrocene-1,2-disulfoxides: synthesis and reactivity

The rational use of directed deprotometallation, sulfur oxidation and sulfoxide/lithium exchange allowed the synthesis of enantiopure ferrocene-1,2-disulfoxide derivatives. Not only do they represent the first members of this original family, but some of them have shown promise as ligands in rhodium-catalysed conjugate addition.

Ir(IV) Sulfoxide-Pincer Complexes by Three-Electron Oxidative Additions of Br2 and I2. Unprecedented Trap-Free Reductive Elimination of I2 from a formal d5 Metal

Oxidative addition of 1.5 equiv of bromine or iodine to a Ir(I) sulfoxide pincer complex affords the corresponding Ir(IV) tris-bromido or tris-iodido complexes, respectively. The unprecedented trap-free reductive elimination of iodine from the Ir(IV)-iodido complex is induced by coordination of ligands or donor solvents. In the case of added I^-, the isostructural tris-iodo Ir(III)-ate complex is quickly generated, which then can be readily reoxidized to the Ir(IV)-iodido complex with FcPF₆ or electrochemically. DFT calculations indicate an "inverted ligand field" in the Ir(IV) complexes and favor dinuclear pathways for the reductive elimination of iodine from the formal d⁵ metal center.

Organocatalytic asymmetric synthesis of β,β-diaryl ketones via one-pot tandem dehydration/1,6-addition/decarboxylation transformation of β-keto acids and 4-hydroxybenzyl alcohols

Herein we describe an organocatalytic protocol for the asymmetric synthesis of β,β-diaryl ketones. Under the catalysis of a chiral phosphoric acid, 4-hydroxybenzyl alcohols underwent dehydration to form para-quinone methides, which reacted with β-keto acids in 1,6-addition reactions. Upon treatment with Et₃N in one-pot, decarboxylation proceeded to provide the desired chiral ketones in nearly quantitative yields with high enantioselectivities.

Rh-Catalyzed Highly Enantioselective Synthesis of Aliphatic Sulfonyl Fluorides

Rh-catalyzed, highly enantioselective (up to 99.8% ee) synthesis of aliphatic sulfonyl fluorides was accomplished. This protocol provides a portal to a class of novel 2-aryl substituted chiral sulfonyl fluorides, which are otherwise extremely difficult to access. This asymmetric synthesis has the feature of mild conditions, excellent functional group compatibility, and wide substrate scope (51 examples) generating a wide array of structurally unique chiral β-arylated sulfonyl fluorides for sulfur(VI) fluoride exchange (SuFEx) click reaction and drug discovery.

Steric Tuning of Sulfinamide/Sulfoxides as Chiral Ligands with C1, Pseudo-meso, and Pseudo-C2 Symmetries: Application in Rhodium(I)-Mediated Arylation

A new family of sulfinamide/sulfoxide derivatives was synthesized as chiral bidentate ligands by stereoselective additions of methylsulfinyl carbanions to N-tert-butylsulfinylimines. The new ligands, with C₁, pseudo-meso, and pseudo-C₂ symmetries, were successfully assayed in Rh-catalyzed additions of arylboronic acids to activated ketones. The sterically dissymmetric C₁ ligand (R_S,S_C,R_S)-N-[1-(phenylsulfinyl)-3-methylbut-2-yl] tert-butylsulfinamide turned out to be the optimal one, allowing the 1,4-additions of diverse arylboronic acids, on different α,β-unsaturated cyclic ketones with high chemical yields and enantioselectivities up to >99% ee.

Internal asymmetric induction by the C-6 substituent on the oxidation reaction of interglycosidic sulfur atom of thiodisaccharides

Complete diastereoselectivity was archived in the oxidation of 3-deoxy-S-(1-4)-disaccharides due to anchimeric assistance of the terminal CH₂OH group.

Pseudo enantiomeric mixed S/P ligands derived from carbohydrates for the 1,4-addition of phenyl boronic acid to cyclohexenone

Mixed S/P ligands 3 and 10, good catalyst precursors for the Rh(i)-catalysed 1,4-addition of phenylboronic acid to cyclohexenone behave as enantiomers even though both derived from d-sugars.

Facile synthesis of enantioenriched phenol-sulfoxides and their aluminum complexes

Chiral phenolic p-tolylsulfoxides, t-butylsulfoxides and well-defined aluminum complexes were prepared by short synthetic routes from readily available starting materials.

The emergence of sulfoxides as efficient ligands in transition metal catalysis

Sulfoxides are capable of forming stable complexes with transition metals and there have been many comprehensive studies into their binding properties. However, the use of sulfoxides, particularly chiral sulfoxides, as ligands in transition metal catalysis is rather less well developed. This review aims to describe these catalytic studies and covers new developments that are showing very promising results and that have led to a renewed interest in this field.

Computational modelling of the enantioselectivity in the asymmetric 1,4-addition reaction catalyzed by a Rh complex of a S-chiral disulfoxide

Computational chemistry is a powerful tool for understanding chiral catalysis and can also aid future catalyst design.

“Sulfolefin”: a mixed sulfinamido-olefin ligand in enantioselective rhodium-catalyzed addition of arylboronic acids to trifluoromethyl ketones

Trifluoromethyl-substituted tertiary alcohols were obtained with good yields and enantioselectivities using the shelf stable sulfolefin-1 as a catalyst precursor.