Dimeric cinchona ammonium salts with benzophenone linkers: enantioselective phase transfer catalysts for the synthesis of α-amino acids

Abstract

Novel cinchona-alkaloid derived dimeric phase transfer catalysts (PTC) with benzophenone linkers and their α-alkylation of glycinate esters has been presented.

Self-assembly of a new class of rhenium(i)-based double stranded dinuclear monohelicates with their photophysical and electrochemical studies

“…Bis(4-(bromomethyl)phenyl)methane and bis(4-(bromomethyl)phenyl)methanone were prepared by following known procedures. 15 ATR-IR spectra were recorded on a Nicolet iS5 IR spectrophotometer. NMR spectra were recorded on a Bruker Avance III 500 MHz spectrometer.…”

Chiral Aldehyde Catalysis Enables Direct Asymmetric Substitution Reaction of N-Unprotected Amino Acids with Halohydrocarbons

“…In this work, we report on three chiral aldehyde-catalyzed asymmetric substitution reactions of N-unprotected amino acid esters with aryl halides, [39][40][41][42][43][44] allyl chlorides, and benzyl chlorides. [45][46][47][48][49][50][51][52][53][54][55][56][57][58][59] Although the N-functionalization byproducts are not suppressed completely, the de-sired C-functionalization products can be generated in moderate-to-high yields with good-to-excellent enantioselectivities for all three transformations. Furthermore, the arylation product is used for the formal total synthesis of the clinical candidate compound (+)-AG-041R, and three reaction models are proposed based on the results of control experiments and density functional theory (DFT) calculations.…”

H-Bond Mediated Phase-Transfer Catalysis: Enantioselective Generating of Quaternary Stereogenic Centers in β-Keto Esters

“…Among organocatalytic methods, phase transfer catalytic (PTC) reactions represent one of the simplest and most efficient tools for enantio-differentiation synthesis [32][33][34][35]. The most commonly used chiral catalysts of natural origin are ammonium salts, derivatives of Cinchona alkaloids, among others, due to their availability and economic considerations [36][37][38][39]. Moreover, it has been repeatedly shown that the use of large substituents on the nitrogen atom of the quinuclidinium ring improves the properties of such a catalyst [40,41].…”