Contrast performance in catalytic ability—new cinchona phase transfer catalysts for asymmetric synthesis of α-amino acids

Recent applications of Cinchona alkaloids and their derivatives as catalysts in metal-free asymmetric synthesis

“…A study by Elango and co-workers has shown that optimisation of the bulkiness at the quaternary nitrogen is also important in controlling the enantioselectivity. 102 The Cinchona alkaloid PTC may not be a better performer when sterically overcrowded with the quaternising group. Sirit and co-workers used three calixarene-based quaternary ammonium salts of Cinchona alkaloids in benzylation of glycine imine ethyl ester to achieve up to 57% enantioselectivity.…”

Synthesis, anti-inflammatory activity of picen-13-ylmethylene derivatives

“…23 In our study, mild reducing agents like di-isobutyl aluminium hydride [DIBAL (1M in Toluene)] was used to reduce picene-13-carboxylic acid ethyl ester 6 to picen-13-ylmethanol 9 24 in 90% yield. It was found that the oxidation of compound 9 with manganese dioxide 11 in dichloromethane was not completed even under reflux condition.…”

Cinchona Alkaloids in Asymmetric Organocatalysis

“…Elango et al synthesized quaternary cinchona derivatives with very bulky arylmethyl groups on N1, with the hope of strengthening the eventual -interactions between catalyst and substrate which could beneficially affect the outcome of the reaction. 239 Interestingly, while an N-picenylmethyl-substituted catalyst gave substantially no asymmetric induction, the corresponding N-pyrenylmethyl-substituted catalyst afforded products with optical purities comparable to those obtained with compound DHCN-39. Kumar and Ramachandran synthesized phase-transfer catalysts with an N-benzyl substituent containing diarylcarbinol units on the meta-and para-positions.…”