Friedel-Crafts Reaction of Indoles with Isatin-Derived β,γ-Unsaturated α-Keto Esters Using a BINOL-Derived Bisoxazoline (BOX)/Copper(II) Complex as Catalyst

• Published in: Advanced synthesis & catalysis Vol. 358; no. 19; pp. 3100 - 3112
• Main Authors: Li, Nai-Kai, Kong, Ling-Pei, Qi, Zheng-Hang, Yin, Shao-Jie, Zhang, Jun-Qi, Wu, Bing, Wang, Xing-Wang
• Format: Journal Article
• Language: English
• Published: WEINHEIM Blackwell Publishing Ltd 06.10.2016; Wiley
• Subjects: 3,3′-bisindoles; 3-keto ester-3-indolyloxindoles; 3′-bisindoles; asymmetric Friedel-Crafts reaction; Chemistry; Chemistry, Applied; Chemistry, Organic; indoles; isatin-derived β; isatin-derived β,γ-unsaturated α-keto esters; Physical Sciences; Science & Technology; γ-unsaturated α-keto esters; ASYMMETRIC-SYNTHESIS; ORGANOCATALYTIC CONSTRUCTION; LEWIS-ACID; EFFICIENT SYNTHESIS; asymmetric Friedel-Crafts reaction; CHIRAL PHOSPHORIC-ACID; 3,3 '-bisindoles; isatin-derived beta,gamma-unsaturated alpha-keto esters; MICHAEL ADDITION; indoles; 3-keto ester-3-indolyloxindoles; N-ALKYLATION; TETHERED BIS(OXAZOLINE); ENANTIOSELECTIVE TOTAL-SYNTHESIS; OXINDOLE DERIVATIVES
• ISSN: 1615-4150; 1615-4169
• DOI: 10.1002/adsc.201600272

Several chiral BINOL‐derived bisoxazoline (BOX)/copper(II) complexes were synthesized and evaluated as catalysts for the Friedel–Crafts reaction of indoles with isatin‐derived β,γ‐unsaturated α‐keto esters. The resulting bis‐indole products bearing a quaternary stereocenter were obtained in excellent yields and enantioselectivities. Additionally, the desired products were practically transformed to α‐amino esters, α‐hydroxy esters and α‐keto amides. It is noteworthy that this catalytic procedure was conducted with a catalyst loading of 0.5 mol% without any discernible decrease in the reactivity or enantioselectivity.