Organocatalytic Enantioselective Construction of Axially Chiral Sulfone-Containing Styrenes

Abstract

We describe herein an organocatalytic enantioselective approach for the construction of axially chiral sulfone-containing styrenes. Various axially chiral sulfone-containing styrene compounds were prepared with excellent enantioselectivities (up to >99% ee) and almost complete E/ Z selectivities (>99% E/ Z). Furthermore, the axially chiral sulfone-containing styrenes could be easily converted into phosphonic acid and S/P ligands, which could be potentially used as organocatalysts or ligands in asymmetric catalysis.

Synthesis of Axially Chiral Styrenes through Pd‐Catalyzed Asymmetric C−H Olefination Enabled by an Amino Amide Transient Directing Group

“…[11b] Inspired by this pionnering work, a number of a-amino acid derived amides were screened (Tables S3 and S7) and we were delighted to find that tert-leucine-derived amino amide TCA-1 was the optimal one. Control experiments on the effect of other additives were tested (entries [4][5][6][7][8][9][10][11][12]. The choices of oxidants and solvents were crucial for this reaction.…”

“…To date, the only strategy for its efficient synthesis is the asymmetric organocatalytic addition recently developed by the Tan and Yan groups. [9] The mild reaction conditions generally used in organocatalytic synthesis (at or below room temperature) ensure high enantiocontrol in the transition state and maintenance of the chirality of the resulting styrene atropoisomers.Recently, asymmetric C À H functionalization has emerged as a powerful synthetic approach for rapid access to axially chiral biaryls. [4f,h, 10] Inspired by the pioneering work by Yu and co-workers on the construction of central chirality through transient chiral auxiliary (TCA)-enabled CÀH functionalization, [11] we recently reported the highly atroposelective construction of biaryl atropoisomers using tert-leucine (Tle) as a TCA.…”

“…To date, the only strategy for its efficient synthesis is the asymmetric organocatalytic addition recently developed by the Tan and Yan groups. [9] The mild reaction conditions generally used in organocatalytic synthesis (at or below room temperature) ensure high enantiocontrol in the transition state and maintenance of the chirality of the resulting styrene atropoisomers.…”

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

“…On the basis of the previous studies,– a plausible reaction pathway is depicted (Scheme ). Firstly, the electrophilic sulfur reagent is activated by catalyst C11 to form intermediate I under the assistance of a Lewis acid.…”

“…Intermediate I reacts with substrate 1 to give thiirenium ion intermediate II with an acid‐derived anion bridge. Then, intermediate II may be further converted to a chiral aza‐vinylidene‐quinone methide (aza‐VQM) intermediate III and regenerate the catalyst –. The following intramolecular hydroarylation on the intermediate III results in axially chiral product 3 .…”