749922-75-6Relevant academic research and scientific papers
10b-Substituted hexahydropyrrolo-isoquinolines: Studies on diastereoselective formation of a quaternary carbon stereocenter via N-acyliminium ion cyclization
Ka?uza, Zbigniew,Mostowicz, Danuta,Do??ga, Grzegorz,Mroczko, Katarzyna,Wójcik, Robert
, p. 943 - 953 (2007/10/03)
The stereoselective synthesis of hexahydro-pyrroloisoquinolines with a quaternary carbon stereocenter is described. The presented methodology employs the addition of a Grignard reagent to the carbonyl group of imide 1, derived from l-tartaric acid, followed by acetylation and BF3·Et 2O induced cyclization. The acetylation-cyclization sequence can be run either as a one-pot process, or stepwise in a selected solvents. The crucial step, an acid-catalyzed carbon-carbon bond-forming reaction via an N-acyliminium ion offers high stereoselectivity, which has been shown to be strongly dependent on the size of the R1 substituents and the reaction conditions, that is, choice of solvent, amount of a Lewis acid, temperature, and concentration of the substrate. Based on the results observed, participation of solvent in the cyclization, via an N-acyliminium cation is proposed.
Diastereoselective synthesis of 10b-substituted hexahydropyrroloisoquinolines from L-tartaric acid. Creation of a quaternary carbon stereocentre via N-acyliminium ion cyclization
Mostowicz, Danuta,Wójcik, Robert,Do??ga, Grzegorz,Ka?uza, Zbigniew
, p. 6011 - 6015 (2007/10/03)
A simple, three-step synthesis of 10b-substituted- hexahydropyrroloisoquinolines 12-17 starting from an L-tartaric acid derived imide is described. The methodology presented employs the addition of a Grignard reagent to the imide carbonyl group, followed by a one-pot acetylation- cyclization sequence. The crucial step, an acid-catalyzed carbon-carbon bond forming reaction via an N-acyliminium ion offers moderate to high stereoselectivity, which has been shown to be strongly dependent on the size of the R-substituent. The mixtures of pyrroloisoquinolines obtained can be separated as enantiomerically pure 2-silyloxy-derivatives.
