A new chiral bicyclic guanidine-catalyzed direct catalytic aldolreaction of 5H-oxazol-4-ones with aldehydes has been developed. The present aldolreaction proceeds smoothly with high enantioselectivity using bicyclic guanidines bearing a hydroxy group at the appropriate position, and various combinations of 5H-oxazol-4-ones and aldehydes are applicable. The method provides synthetically useful alpha
Organocatalytic 1,4‐Addition Reaction of 2‐Formyl(thio)esters to Vinylketones: An Efficient Access to Acyclic Chiral Building Blocks with a Quaternary Carbon Stereocenter
2‐Formyl(thio)esters were utilized as pronucleophiles to obtain less‐accessible acyclicchiralbuildingblocks bearing versatile functional groups on a quaternarycarbon atom for enantioselective 1,4‐addition to vinylketones. To achieve high enantioselectivity in the present 1,4‐additionreaction, thiourea‐tertiary amines containing a bulky chiral backbone were developed as catalysts, and several derivatizations
New class of amino-phosphinite chiral catalysts for the highly enantioselective addition of arylzinc reagents to aldehydes
作者:Marcelo Godoi、Eduardo E. Alberto、Marcio W. Paixão、Liliana A. Soares、Paulo H. Schneider、Antonio L. Braga
DOI:10.1016/j.tet.2009.12.009
日期:2010.2
A new class of amino-phosphinite chiral ligands was prepared and applied in zinc-catalyzed addition of aryl boronic acids to aldehydes; the reaction furnished the diarylmethanols in excellent yields and with a high level of enantioselectivity (up to 93% ee).
Aziridin-2-yl methanols as organocatalysts in Diels–Alder reactions and Friedel–Crafts alkylations of N-methyl-pyrrole and N-methyl-indole
作者:Bianca F. Bonini、Elena Capitò、Mauro Comes-Franchini、Mariafrancesca Fochi、Alfredo Ricci、Binne Zwanenburg
DOI:10.1016/j.tetasy.2006.11.028
日期:2006.11
A series of enantiomerically pure aziridin-2-yl methanols have been synthesized from aziridine-2-carboxylic esters and have been tested as organocatalysts in Diels-Alder reactions and Friedel-Crafts alkylations of N-methyl-pyrrole and N-methyl-indole using alpha,beta-unsaturated aldehydes. Moderate to good ee's have been obtained. The coupling of N-methyl-pyrrole with crotonaldehyde and cinnamaldehyde using (2S,3S)-3-methylazirin-2-yl(diphenyl)methanol TFA salt as the catalyst gave the best results (ee 75%). (c) 2006 Elsevier Ltd. All rights reserved.
Willems, Johannes G. H.; Hersmis, Marco C.; De Gelder, Rene, Journal of the Chemical Society. Perkin transactions I, 1997, # 6, p. 963 - 967
作者:Willems, Johannes G. H.、Hersmis, Marco C.、De Gelder, Rene、Smits, Jan M. M.、Hammink, Jeannet B.、Dommerholt, F. Jan、Thijs, Lambertus、Zwanenburg, Binne