Chiral N-aryl tert-butanesulfinamide-olefin ligands for rhodium-catalyzed asymmetric 1,4-addition of aryl boronic acids to cyclic enones

Abstract

Chiral N-aryl sulfinamide-olefins which are readily synthesized via C-N coupling and nucleophilic substitution have been used as chiral ligands, which demonstrate moderate to excellent asymmetric catalytic performance in the rhodium-catalyzed asymmetric 1,4-addition of aryl boronic acids to cyclic enones. The chiral ligands are readily synthesized via C-N coupling reaction and nucleophilic substitution. Given that chiral ligands with 97%ee produced 1,4-addition products up to 95%ee, N-aryl tert-butanesulfinamide-olefin ligands demonstrates fairly high chiral induction ability in the rhodium-catalyzed asymmetric 1,4-addition.

Recent Advances for Chiral Sulfoxides in Asymmetric Catalysis

“…In 2016, Zeng and coworkers exploited a novel chiral N-aryl tertbutyl sulfonamide olefin ligand in the rhodium-catalyzed asymmetric 1,4-addition reaction of arylboronic acids to cycloolefins (Scheme 27). [49] When (R)-N-allyl-N-phenyl-tertbutane-sulfonamide L46 was chosen as chiral ligand to study the reaction, the product was obtained in a moderate enantioselectivity (63% ee). Enantioselectivity and yields of the products were significantly increased when allyl group was replaced by cinnamyl group.…”

“…In 2017, Zeng and co-workers exploited a novel chiral Naryl-N-tert-butanesulfinamide-olefin ligand in the Rh-catalyzed asymmetric 1,4-addition reaction of arylboronic acids to cycloalkenones (Scheme 27). 49 For the model reaction of cyclohex-2-enone with 4-tolylboronic acid catalyzed by [RhCl(C 2 H 4 ) 2 ] 2 , using (R)-N-allyl-N-phenyl-tert-butanesulfinamide (L46) as the chiral ligand gave 3-(4-tolyl)cyclohexanone with moderate enantioselectivity (63% ee). Replacing the N-allyl group in L46 by a cinnamyl group to give (R)-Ncinnamyl-N-phenyl-tert-butanesulfinamide (L47) significantly increased the ee of the product to 89% ee.…”

Kinetic Resolution of Sulfinamides via Asymmetric N-Allylic Alkylation

“…Furthermore, recovered ( R )- 1a can be converted into product ( R )- 7 with almost unchanged enantioselectivity by one-step simple allylation (Scheme c). It is valuable to note that ( R )- 7 can be used as a ligand in the 1,4-addition of boronic acids to α,β-unsaturated ketones …”

“…It is valuable to note that (R)-7 can be used as a ligand in the 1,4-addition of boronic acids to α,β-unsaturated ketones. 18 A sulfinamide computational study was then conducted to understand the enantioselectivity established in the kinetic resolution product. 19 The lowest-energy diastereomeric transition states were thus explored.…”