Enantioselective synthesis of 2-isoxazolines by a One-flask conjugate addition/oxime-transfer process
A study was conducted to demonstrate a new catalytic enantioselective method to prepare 5-substituted 2-isoxazolines that applied a small organic catalyst as the source of chirality and enabled the use of different α-β-unsaturated aldehydes as starting materials. The aldehyde and acetone oxime were added to a solution of amine and benzoic acid in toluene at 0 °C. A precooled solution of H2SO4 in MeOH was added and the resulting solution was stirred for 15 minutes at 0 °C after stirring the reaction mixture at 0 °C for the indicated period of time. A saturated aqueous solution of NaHCO3 was added and the mixture was extracted with EtOAc. The combined organic extracts were dried and concentrated, while the residue was purified by flash chromatography to afford the products. The results show that the presence of a strong acid in the reaction mixture induced the formation of similar catalytic species in the reactions.
Pohjakallio, Antti,Pihko, Petri M.
supporting information; experimental part
p. 3960 - 3964
(2009/11/30)
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