402489-95-6Relevant academic research and scientific papers
Stereoselective formal [3 + 2] cycloaddition of N-alkylidene glycine ester anions to chiral fischer alkenylcarbene complexes. Asymmetric synthesis of 3,4,5-trisubstituted prolines
Merino, Isabel,Santosh Laxmi,Florez, Josefa,Barluenga, Jose,Ezquerra, Jesus,Pedregal, Concepcion
, p. 648 - 655 (2002)
The reaction between N-alkylidene glycine ester enolates, generated from glycine esters aldimines with LDA in THF at low temperature, and chiral alkoxyalkenylcarbene complexes of chromium provided directly 2,4,5-trisubstituted-3-pyrrolidinylcarbene complexes with total exo selectivity and very high syn and facial diastereoselectivity when carbene complexes bearing the (-)-8-phenylmenthyloxy group were employed. Oxidation of the metal carbene moiety followed by basic hydrolysis of the esters afforded enantiomerically highly enriched syn, exo-3,4,5-trisubstituted prolines, whereas acidic hydrolysis of the same functional groups proceeded with epimerization at the α-amino acid center leading to anti,exo-3,4,5-trisubstituted prolines of very high enantiomeric purity as well.
