Asymmetric metal-free synthesis of fluoroquinolones by organocatalytic hydrogenation
A highly enantioselective organocatalytic transfer hydrogenation enabling the synthesis of both 6-fluoro-2-methyltetrahydroquinoline and 7,8-difluoro-3-methyl-benzoxazine has been developed. These key building blocks can for the first time be synthesized using the same methodology allowing fast and efficient, metal-free access to the antibiotic fluoroquinolones flumequine and levofloxacine.
Rueping, Magnus,Stoeckel, Mirjam,Sugiono, Erli,Theissmann, Thomas
experimental part
p. 6565 - 6568
(2010/10/19)
Synthesis, absolute configuration and intermediates of 9-fluoro- 6,7- dihydro-5-methyl-1-oxo-1H,5H-benzo[i.j]quinolizine-2-carboxylic acid (flumequine)
The antibacterial agent 9-fluoro-6,7-dihydro-5-methyl-1-oxo-1H,5H- benzo[i.j]quinolizine-2-carboxylic acid (flumequine) was synthesized in optically active form from 6-fluoro-2-methyl-1,2,3,4-tetrahydroquinoline (FTHQ). Racemic FTHQ was resolved with the enantiomers of 3-bromocamphor-8- sulfonic acid. The configurations were established by X-ray structures of the two diastereoisomeric salts. Enantiomeric excesses were determined by 1H NMR analysis.
Balint, Jozsef,Egri, Gabriella,Fogassy, Elemer,Boecskei, Zsolt,Simon, Kalman,Gajary, Antal,Friesz, Antal
p. 1079 - 1087
(2007/10/03)
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