56037-56-0Relevant academic research and scientific papers
L-Pipecolinic acid derived Lewis base organocatalyst for asymmetric reduction of N-aryl imines by trichlorosilane: Effects of the side amide group on catalytic performances
Wang, Zhouyu,Wang, Chao,Zhou, Li,Sun, Jian
, p. 787 - 797 (2013/02/25)
A series of N-formamides derived from pipecolinic acid have been synthesized and tested as Lewis base catalysts for the enantioselective reduction of N-aryl imines by trichlorosilane. Through the investigation of the structure-efficacy relationship between the side amide group and catalytic performance, several highly effective catalysts were discovered. In particular, arylamido-type catalyst 5i and non-arylamido-type catalyst 6c exhibited high reactivity and enantioselectivity, furnishing the reduction of a wide variety of N-aryl imines with high isolated yields (up to 98%) and ee values (up to 96%) under mild conditions. Moreover, these two catalysts complement each other in terms of their tolerances to nonaromatic ketimines and non-methyl ketimines. The Royal Society of Chemistry 2013.
A highly enantioselective Lewis basic organocatalyst for reduction of N-aryl imines with unprecedented substrate spectrum
Wang, Zhouyu,Ye, Xiaoxia,Wei, Siyu,Wu, Pengcheng,Zhang, Anjiang,Sun, Jian
, p. 999 - 1001 (2007/10/03)
L-Pipecolinic acid derived formamides have been developed as highly efficient and enantioselective Lewis basic organocatalysts for the reduction of N-aryl imines with trichlorosilane. Catalyst 4b afforded high isolated yields (up to 98%) and enantioselect
Synthesis of 4-Hydroxy-2(1H)-pyridones from Azomethines and Substituted Dialkylmalonates
Kafka,Kappe
, p. 1019 - 1031 (2007/10/03)
The reaction of azomethines 4 with substituted dialkyl malonates 5 leads to the formation of 3-substituted 4-hydroxy-2(1H)-pyridones 6 in moderate yields. The azomethines 4 are prepared via arylaminopropionitriles 3 or in the conventional way by acid catalyzed condensation of ketones 1 with anilines 2. Chlorination of pyridones 6 with sulfuryl chloride leads to compounds 8-10.
Factors Controlling Regioselectivity in Deprotonations of Unsymmetrical Ketimines
Smith, J. Kirk,Bergbreiter, David E.,Newcomb, Martin
, p. 4396 - 4400 (2007/10/02)
The regioselectivity of deprotonation of equilibrium E-Z mixtures of the benzyl, n-butyl, cyclohexyl, phenyl, and tert-butyl imines of 2-butanone by lithium diisopropylamide (LDA) in tetrahydrofuran has been shown to be a function of both the nitrogen substituent and the temperature of the deprotonation reaction.High regioselectivity at either the methyl or methylene substituent could be obtained for all imines except the benzyl and n-butyl imines.Pure (Z)-2-butanone imines (R = n-C4H9, c-C6H11, t-C4H9), prepared by LDA deprotonation of acetone imines followed by methylation, were deprotonated by LDA at the methyl position at -78 deg C and at 0 deg C.Studies of the rates of deprotonation of the E and Z isomers of n-butyl, cyclohexyl, and tert-butyl imines of 2-butanone and of the rates and mechanisms of isomerizations of these isomeric ketimines were performed.Temperature dependent deprotonation regioselectivity was also observed in lithium diethylamide deprotonations of the benzyl, cyclohexyl, phenyl, and tert-butyl imines of 2-butanone.A general scheme accounting for these results and other accounts of variable regioselectivity in ketimine deprotonation is presented.
