Chiral Organosulfur Ligands/Catalysts with a Stereogenic Sulfur Atom: Applications in Asymmetric Synthesis

Abstract

Asymmetric synthesis, in which chiral organocatalysts or metal complexes with chiral ligands are used, has become the most valuable methodology for the preparation of enantiomerically pure organic compounds. Among such catalysts/ligands, a growing number constitute various organosulfur compounds. This Review provides comprehensive and critical information on the plethora of sulfur-based chiral ligands and organocatalysts used in asymmetric synthesis, which have been published within the last 15 years. However, it is confined to the presentation of only those chiral catalysts/ligands that possess a stereogenic sulfur atom and includes sulfoxides, sulfinamides, N-sulfinyl ureas, sulfoximines, and some related S-chiral derivatives.

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

“…Interestingly, oxidation of the thiodisaccharide 14 was highly diastereoselective to give the sulfoxide 17R as the unique isomer, in 80% yield. As for the other sulfoxides already described, 17R showed a preference for the 4 The same analysis allowed us to establish the absolute conguration at the sulfur atom of 16S and 16R. As these isomers are populating the same rotamer conformations as found for 16S and 16R, respectively, the invoked anisotropic effects justify the chemical shis of the protons located near to the S]O group.…”

“…In addition, enantiomerically pure sulfoxides are employed as powerful chiral auxiliaries, ligands or catalysts in asymmetric synthesis. [4][5][6][7] Therefore, the enantio or diastereoselective preparation of sulfoxides is a current challenge for synthetic organic chemists. In this regard, a number of procedures for the diastereoselective or enantioselective (including enzymes or microorganisms) sulfoxidations have been reported.…”

Access to the Enantiopure Axially Chiral Cyclophane Isoplagiochin D through Atropo‐diastereoselective Heck Coupling

“…[21] It should be noted that intramolecular variants of the Heck method [22] have been broadly used in natural product syntheses, [23] but asymmetric variants have been applied only for the construction of chiral carbon centers. [24] Thep otential of as ulfoxide moiety has been reported in the atropo-diastereoselective Suzuki-Miyaura coupling reactions, [25] as well as by us in the field of bis(bibenzyls). [26] Regarding the excellent ortho-directing effect of the enantiopure sulfinyl group,w hich was extensively investigated in Colobertsg roup for enantiopure biaryls, [27] we speculated that this auxiliary could now be used for the first atroposelective total synthesis of enantiopure isoplagiochin D(1).…”

Enantioselective Construction of Axially Chiral Amino Sulfide Vinyl Arenes by Chiral Sulfide‐Catalyzed Electrophilic Carbothiolation of Alkynes

“…They are prevalent in many natural products and bioactive molecules, [1] and are useful chiral ligands and catalysts in enantioselective catalysis. [2] For example, TMC-95A is a biologically active natural product; [3] (SO,SO)-, (P,S)-, or (N,P)difunctionalized compounds A-C can serve as ligands for a variety of metal-catalyzed enantioselective reactions; [4,5] trialkylsulfonium salt D is an efficient bifunctional organocatalyst for the enantioselective conjugate additions of 3substituted oxindoles to maleimides; [6a] biaryl amino alcohol E is a photocatalyst efficiently promoting the enantioselective [2+2] photocycloaddition of 4-alkenyl-substituted coumarins (Figure 1). [6b] Owing to the importance of axially chiral compounds, a large number of catalytic enantioselective synthetic methods have been developed for their synthesis.…”

“…To our delight, when the selenide catalyst was protected by the Ts group, the reaction gave the desired product in excellent yield with 69 % ee (entry 1). Other protecting groups, that is, nosyl-, 4-isopropyl-, and 4-methoxysubstituted benzenesulfonyl groups were slightly less efficient than the Ts group (entries [2][3][4]. When Bz and phosphonate groups were used, the products were formed as an almost racemic mixture (entries 5 and 6).…”