Solvent‐Mediated C3/C7 Regioselective Switch in Chiral Phosphoric Acid‐Catalyzed Enantioselective Friedel‐Crafts Alkylation of Indoles with α‐Ketiminoesters
作者:Yunlong Zhao、Lu Cai、Tongkun Huang、Shanshui Meng、Albert S. C. Chan、Junling Zhao
DOI:10.1002/adsc.201901380
日期:2020.3.17
The first solvent‐mediated tunable C3/C7 regio‐ and enantioselective Friedel‐Crafts alkylation of 4‐aminoindoles with α‐ketimino esters has been developed. This catalysis allows the highly regioselective formation of indole C3 and C7 alkylation products, both in high yields (up to 96%) and excellent enantioselectivities (up to 99% ee). Mechanism study revealed that the hydrogen‐bonding interactions
The acid‐catalyzed reaction of diazoacetates and aldimines (Brookhart–Templeton aziridination) is now recognized as a reliable method to provide enantiomerically enriched disubstituted aziridines, thus owing to the development of asymmetric catalysis. However, the extension of this method to prepare trisubstituted aziridines has not been explored to date, even for racemic products. In this context
Despite the remarkable advances in catalytic asymmetricaziridinations over the past decades, establishing a general procedure for the stereoselective synthesis of trisubstituted aziridines has remained an elusive goal. Chiral N-triflyl phosphoramide-catalyzed reactions of N-α-diazoacyl oxazolidinones and N-Boc imines were developed as a solution to this unmet challenge.
Catalytic Asymmetric Mannich‐Type Reaction of Malononitrile with N‐Boc α‐Ketiminoesters Using Chiral Organic Base Catalyst with Halogen Bond Donor Functionality
Chiral organic basecatalyst with halogen bond donor functionality catalyzed asymmetricMannich‐type reaction of malononitrile with α‐ketiminoesters to produce α,α‐disubstituted α‐amino acid derivatives in good yields with high enantioselectivities. The malononitrile‐derived amino acid was smoothly transformed to chiral aminomalonate without loss of ee.
The first enantioselective hydrophosphonylation of ketimines with phosphine oxides was developed. The reaction of unprotected ketimines with phosphine oxides using a bis(imidazoline)-phosphoric acid catalyst gave chiral α-quaternary aminophosphorous compounds having a primary amino group in excellent yields and enantioselectivities. Based on experimental results and DFT calculation, transition states