Synthesis of four diastereomeric L-2-(carboxycyclopropyl)glycines. Conformationally constrained L-glutamate analogs
摘要:
To determine what conformations of L-glutamate (L-Glu) activate that compound's different receptors in the mammalian central nervous system, four diastereomeric L-2-(carboxycyclopropyl)glycines, 1-4, which are conformationally constrained analogues of the extended and folded conformers of L-Glu, were synthesized and subjected to neutrophysiological assay. Compounds 1-4 were efficiently synthesized from chiral amino acids. Cyclopropanation of the (2S)-2-amino-3-butenol derivative 5b gave intermediates for the synthesis of all four diastereomers. Stereoselective cyclopropanation of both the alpha,beta-unsaturated gamma-lactam 16 and the delta-lactone 19 gave precursors of (2S,1'S,2'R)-3 and (2S,1'R,2'S)-4, respectively. Neurophysiological assays of 1-4 performed with the newborn rat spinal cord demonstrated that the compounds induced a variety of depolarizing effects. The results of the assays strongly suggested that the N-methyl-D-aspartic acid (NMDA) receptor is activated by the folded conformer of L-Glu and that the extended conformer of L-Glu activates the metabotropic L-Glu receptor. The four analogous D-2-(carboxycyclopropyl)glycines (D-1-D-4), which were synthesized from (2R)-5b, proved to be NMDA agonists.
Novel enantioselective synthesis of trans-α-(2-carboxycycloprop-1-yl)glycines: conformationally constrained l-glutamate analogues
作者:Ayhan S Demir、Cihangir Tanyeli、Ali Cagir、M.Nawaz Tahir、Dincer Ulku
DOI:10.1016/s0957-4166(98)00061-5
日期:1998.3
followed by the formation of an oximeether. Enantioselective reduction of the oximeether, separation of diastereomers and oxidation of the furane rings gave enantiomerically pure d- and l-CCG I and CCG II. The structure of oxime 7b was determined by X-ray crystalstructure analysis. The key step is the oxazaborolidine catalyzed enantioselective conversion of oximeethers to amines.
Facile Synthesis of (2S,1′S,2′S)-2-(Carboxycyclopropyl)glycine, an Isotype-Selective Agonist of Metabotropic Glutamate Receptors
作者:Dawei Ma、Zhaochun Ma
DOI:10.1016/s0040-4039(97)10037-5
日期:1997.10
(2S,1'S,2'S)-2-(Carboxycyclopropyl)glycine (L-CCG-I) was synthesized in 12 steps and 14% overall yield by using Sharpless's asymmetric dihydroxylation reaction and stereochemically controlled cyclopropanation as key steps. (C) 1997 Elsevier Science Ltd.