Isolation and identification of contaminants found in commercial dihydroquinine

Effect of Microwave Irradiation on the Catalytic Activity of Palladium Supported Catalysts in the One-Step Isomerisation of Cinchona Alkaloids to Δ3,10-Isobases

“…This procedure was tested to find the optimal Literature data [8][9][10][11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] Oxidative cleavage [12][13][14][15] time for conversion of 1a or 2a to the isomers (Z/E)-3a or (Z/E)-4a. We monitored the ongoing conversion progress of substrates by taking micro-samples of the reaction mixture regularly, at 10-min intervals, which after extraction with diethyl ether in the presence of aqueous ammonia were analyzed by TLC (silica gel plates, methoxyethanol).…”

“…In 1968 it was discovered that migration of double bond in natural quinidine and quinine 1a and 1b occurs during their commercial hydrogenation with Pd-C catalyst and furthermore that Δ 3,10 -isomers 3a and 4a are resistant to subsequent hydrogenation [22]. The effective isomerisation of methoxy alkaloids 1a and 2a to (Z/E)-3a and (Z/E)-4a was performed using rhodium solid supported catalysts (Rh/SS) in a medium of 50% EtOH in the presence of HCl under heating in water bath for a period of 24 h [23].…”

Catalytic Oxidation of Quinine Using Hydrogen Peroxide with Palladium as Catalyst

“…Since pi orbital can interact with palladium to form a palladium pi complex, translocation of the alkene in the molecule of quinine can occur to produce a more thermodynamically stable bond. The product translocation is also reported in the process of palladium-catalyzed hydrogenation of quinine produced in which the cis and trans olefin have been obtained as impurities [12]. The translocation of alkenes in the presence of palladium even occurred in cinchona alkaloid by heating in water [13].…”