246233-16-9Relevant academic research and scientific papers
Efficient asymmetric synthesis of novel 4-substituted and configurationally stable analogues of thalidomide
Yamada, Takeshi,Okada, Takuya,Sakaguchi, Kazuhiko,Ohfune, Yasufumi,Ueki, Hisanori,Soloshonok, Vadim A.
, p. 5625 - 5628 (2007/10/03)
The preparation of new thalidomide derivatives 4-methyl-(3S,4R)-3a and 4-phenyl-(3S,4S)-3b starting from pyroglutamic acids (2R,3R)-7a and (2R,3S)-7b, possessing an inappropriate stereochemistry, was successfully realized due to stereochemically complete epimerization at the α-stereogenic center upon formation of the corresponding N-phthaloyl anhydrides 9a,b. The demonstrated conformational stability of these new thalidomide derivatives provides solid experimental evidence for practical feasibility of the approach described here to overcome the inherent problem of configurational instability of thalidomide by introducing an alkyl or aryl group in the C4 position.
Stereoselective Michael addition of glycine anions to chiral fischer alkenylcarbene complexes. Asymmetric synthesis of β-substituted glutamic acids
Ezquerra, Jesus,Pedregal, Concepcion,Merino, Isabel,Florez, Josefa,Barluenga, Jose,Garcia-Granda, Santiago,Llorca, Maria-Amparo
, p. 6554 - 6565 (2007/10/03)
The reaction of lithium enolates of achiral N-protected glycine esters with chiral alkoxyalkenylcarbene complexes of chromium provided the corresponding Michael adducts with either high anti or syn selectivity depending on the nature of the nitrogen protecting group, and high diastereofacial selectivity when carbene complexes containing the (-)-8- phenylmenthyloxy group were employed. subsequent oxidation of the metal- carbene moiety followed by deprotection of the amine group and hydrolysis of both carboxylic esters afforded enantiomerically enriched 3-substituted glutamic acids of natural as well as unnatural stereochemistry. Alternatively, when the deprotection step was performed previously to the oxidation, cyclic aminocarbene complexes were formed, which finally led to optically active 3-substituted pyroglutamic acids.
