767291-68-9Relevant academic research and scientific papers
Synthesis of novel derivatives of (1S,4S)-2,5-diazabicyclo[2.2.1]heptane and their evaluation as potential ligands in asymmetric catalysis
Melgar-Fernandez, Roberto,Gonzalez-Olvera, Rodrigo,Olivares-Romero, J. Luis,Gonzalez-Lopez, Vianney,Romero-Ponce, Leticia,Ramirez-Zarate, Maria Del Refugio,Demare, Patricia,Regla, Ignacio,Juaristi, Eusebio
, p. 655 - 672 (2008/09/17)
Thirty-seven (most of them novel) chiral derivatives of (1S,4S)-2,5-diazabicyclo[2.2.1]heptane (2-36, 38, 39) were prepared from (S)-trans-4-hydroxyproline. A selection of these chiral ligands were examined as potential ligands in the preparation of catalysts for the enantioselective addition of diethylzinc to aldehydes and as chiral Lewis acid activators in the asymmetric Diels-Alder reaction. In the former system, diamine 30 induced up to 92 % enantiomeric excess in the formation of (S)-phenyl ethyl carbinol, whereas in the case of the cycloaddition reaction between cyclopentadiene and 3-acryloyloxazolidin-2-one the catalytic complex formed between dimeric derivative 8 and copper triflate [Cu(OTf)2] afforded the expected product in a 95:5 endo/exo ratio and up to 72 % ee for the major diastereomeric product. Finally, some of the novel chiral diamines prepared in this work were also evaluated as potential organocatalysts in the asymmetric amination of ethyl α-phenyl-α-cyano acetate. Bifunctional derivative 12 provided the animated product in excellent yield and with up to 40 % ee. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
Effect of ligand structure on the asymmetric cyclization of achiral olefinic organolithiums
Mealy, Michael J.,Luderer, Matthew R.,Bailey, William F.,Sommer, Michael Bech
, p. 6042 - 6049 (2007/10/03)
The ability of a large and chemically diverse set of 30 chiral ligands to effect asymmetric cyclization of 2-(N,N-diallylamino)phenyllithium (1), derived from N,N-diallyl-2-bromoaniline (2) by low-temperature lithium-bromine exchange, has been investigated in an attempt to elucidate the structural motifs required to provide high enantiofacial selectivity in the ring closure. Although none of the ligands examined in this study afforded 1-allyl-3-methylindoline in significantly higher ee than previously observed for the cyclization of 1 in the presence of the benchmark ligand (-)-sparteine, several ligands, structurally unrelated to sparteine and available in either enantiomeric form, were found to match the utility of (-)-sparteine in this chemistry.
