340161-32-2Relevant academic research and scientific papers
Chiral lithium amido sulfide ligands for asymmetric addition reactions of alkyllithium reagents to aldehydes
Granander, Johan,Sott, Richard,Hilmersson, Goeran
, p. 439 - 447 (2007/10/03)
Six chiral amino sulfides have been synthesised from the amino acids phenylalanine, phenylglycine and valine. These amino sulfides were used as chiral ligands in the asymmetric addition of n-butyllithium and metyllithium to various aldehydes at low temperatures. The highest stereoselectivities were obtained with benzaldehyde, resulting in 1-phenyl-1-pentanol and 1-phenyl-1-ethanol in enantiomeric excesses of >98.5 and 95%, respectively. These stereoselectivities were significantly higher than those induced by the ether analogues.
New auxiliaries for copper-catalyzed asymmetric Michael reactions: Generation of quaternary stereocenters at room temperature
Christoffers, Jens,Mann, Alexander
, p. 1014 - 1027 (2007/10/03)
Dialkyl amides of L-valine, L-isoleucine, and L-tert-leucine (2) are excellent chiral auxiliaries for the construction of quaternary stereocenters at ambient temperature. Enaminoesters 3, prepared from these auxiliaries 2 and Michael donors 1. undergo a copper-catalyzed asymmetric Michael reaction with methyl vinyl ketone (MVK, 4) to afford products 5 in 70-90% yield and 90-99% ee (enantiomeric excess). The exclusion of moisture or oxygen is not necessary. The auxiliaries 2 are readily available by standard procedures. After workup they can be recovered almost quantitatively.
New chiral auxiliaries for the construction of quaternary stereocenters by copper-catalyzed Michael reactions
Christoffers, Jens,Mann, Alexander
, p. 2752 - 2754 (2007/10/03)
The construction of quaternary stereocenters with 95-99% ee at ambient temperatures can be achieved by a copper-catalyzed Michael reaction with the application of α-amino acid amides as chiral auxiliaries [Eq. (1)]. These amides can be obtained in a few steps from the α-amino acids with standard transformations and, after the Michael reaction, they can be quantitatively recovered. Exclusion of water and oxygen is not necessary.
