Phase quinidine-derived

M. Lammerhofer and W. Lindner, Quinince and quinidine derivatives as chiral selectors. Beush type chiral stationary phases for high performance liquid chromatography based on chincona carbamates and their applications as chiral anion exchanger, J. Chromatogr. 741 (1966), 33. 

In 2010 the Palomo group used the related quinidine-derived phase-transfer catalyst 109 to facilitate the addition of sulfonylacetonitrile 110 to either A-Boc-protected a-amidosulfones 107 or imines (not shown) in order to obtain - upon subsequent treatment with Mg in MeOH - the enantioenriched a-unsubstituted P-aminonitriles llla-f (Scheme 5.45) [62]. The latter compounds were obtained in moderate to good yields (65-85%) and moderate ee (55-76%). 

The Plaquevent group achieved a new and efficient method for the approach to both enantiomers of methyl dihydrojasmonate 47 by asymmetric Michael addition under solid-liquid phase-transfer catalysis. The main advantages of their procedure are the solvent-free system and the creation of two contiguous stereogenic centres in one step. The authors proposed a plausible mechanism with a transition state composed of substrate 45 and catalyst, quinine-, or quinidine-derived PTC catalyst (48a, 49a), in which hydrogen bonding ensures the proximity of the reactive centres and significantly stabilises the transition state (Scheme 16.14). ... 

The quinidine-derived ammonium salt (330) has been employed as a phase-transfer catalyst for the Michael-initiated ring-closing reaction (MIRC) of bromomalonates BrCH(C02R)2 to electron-neutral and electron-deficient chalcones ArCH=CHCOAr. 

Xiao TL, Armstrong DW (2004) Macrocyclic antibiotics. Chapter 4. In Giibitz G, Schmid MG (eds) Chiral separations, methods and protocols. Humana Press, Totowa, NJ, pp 113-171 Lammerhofer M, Lindner W (1996) Quinine and quinidine derivatives as chiral selectors. I. Brush type chiral stationary phases for high-performance Uquid chromatography based on cinchonan carbamates and their application as chiral anion exchangers. J Chromatogr A 741 33-48... 

Lammerhofer M, Lindner W (1996) Quinine and quinidine derivatives as chiral selectors. 1. Brush type chiral stationary phases for HPLC based on dnchonan carbamates and their application as chiral anion exchangers. J Chromatogr A 741 33-48... 

Figure 12.4 Dihydrocinchonidine- and quinidine-derived quaternary ammonium salt phase-transfer catalysts.

The first silica-supported CSP with a cinchona alkaloid-derived chromatographic ligand was described by Rosini et al. [20]. The native cinchona alkaloids quinine and quinidine were immobilized via a spacer at the vinyl group of the quinuclidine ring. A number of distinct cinchona alkaloid-based CSPs were subsequently developed by various groups, including derivatives with free C9-hydroxyl group [17,21-27] or esterified C9-hydroxyl [28,29]. All of these CSPs suffered from low enantiose-lectivities, narrow application spectra, and partly limited stability (e.g., acetylated phases). 

All catalytic enantioselective versions of the Darzens condensation are based on the use of chiral phase-transfer agents, e.g. the cations 184a,b derived from ephed-rine, quinine/quinidine-based ammonium ions such as 185a,b, or the crown ether 186. 

Phase-transfer catalysis has been widely been used for asymmetric epoxidation of enones [100]. This catalytic reaction was pioneered by Wynberg et al., who used mainly the chiral and pseudo-enantiomeric quaternary ammonium salts 66 and 67, derived from the cinchona alkaloids quinine and quinidine, respectively [101-105],... 

Three chiral stationary phases that were prepared by derivatizing y-mercaptopropylsilanized silica gel with quinine (CSP II), quinidine (CSP III), and cinchonidine (CSP IV), have been used for the successful resolution of N-acyl derivatives of fl-hydroxyphenethylamines [25]. UV and CD detectors set at 270 nm were used in series. The effectiveness of the separation and the detection are illustrated in Figure 6 for the resolution of the N-(3,5-dinitrobenzoyl) derivative of phenylethanolamine on CSP III. 

In 2008, Itoh and co-workers [66] successfully developed the first organocata-lyzed a-aminoxylation of oxyindoles using a cinchonidine-derived phase-transfer catalyst 29 and molecular oxygen (Scheme 12.7). In 2010, Barbas III and co-workers [67] designed a new dimeric quinidine catalyst 28 to synthesize the same kind of... 

Quinine and quinidine carbamate phases have recently been commercialized by Daicel [23]. These selectors derived from natural alkaloids of the chinolin-type show great potential for enantiomer separations of polar analytes, such as N-derivatized amino acids and peptides, amido sulfonic adds, and non-derivatized acids. 

N-Benzotriazole derivatives of quinine and quinidine were applied as phase-transfer catalysts for the nitro-Mannich reaction between a-amido-sulfones and nitroalkanes (Scheme 6.57) [119]. The products were formed in good yields and high enantioselechvihes and could be transformed efficiently into either a diamine... 

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