Design of Chiral Bifunctional Dialkyl Sulfide Catalysts for Regio‐, Diastereo‐, and Enantioselective Bromolactonization

Abstract

Although a wide variety of chiral organocatalysts have been developed for asymmetric transformations, effective chiral dialkyl sulfide organocatalysts remain relatively rare and under-developed, despite the potential utility of dialkyl sulfide catalysts. Herein, we report the development of chiral bifunctional dialkyl sulfide catalysts possessing a urea moiety for regio-, diastereo-, and enantioselective bromolactonization. The importance of the bifunctional design of chiral sulfide catalysts was clearly demonstrated in the present work. The roles of both the sulfide and urea moieties of the catalyst were clarified based on the results of experimental and theoretical investigation.

Organocatalytic asymmetric N-sulfonyl amide C-N bond activation to access axially chiral biaryl amino acids

“…6). To our delight, these organocatalysts gave comparable or even better outcomes in terms of yield and ee than the previous symmetric organocatalysts under the same reaction conditions [68][69][70] . These initial results indicate that unsymmetrical axially chiral biaryl compounds synthesized in our present strategy have great potential as organocatalysts and ligands in asymmetric catalysis.…”

Halogen-Induced Controllable Cyclizations as Diverse Heterocycle Synthetic Strategy

“…This catalyst showed high endo/exo selectivity and moderate enantioselectivity depending on the substituents present in the substrates. Substrates possessing electron-donating substituents at the non-nucleophilic aryl moiety (65) undergo endo-cyclization [81], while those possessing electron-withdrawing substituents (65') undergo exo-cyclization [82]. This endo/exo selectivity was thus determined to be governed by the electronic factors of the aryl moiety.…”

Solvent and catalyst-free bromofunctionalization of olefins using a mechanochemical approach

“…4 Thus, milder and more user-friendly halogen sources such as N-bromosuccinimide (NBS) and 1,3-dibromo-5,5dimethylhydantoin (DBDMH) are frequently employed in many bromofunctionalization reactions. 5 Well reported examples include bromocyclization reactions such as bromolactonization [6][7][8][9][10][11][12][13][14][15] and bromoetherication [16][17][18][19] as well as the more challenging intermolecular bromoesterication. [20][21][22][23][24][25][26] Because of the high polarity of the N-bromoimide reagents, polar solvents such as N,N-dimethylformamide and acetonitrile are oen required for good solvation which poses difficulties in the purication process.…”