(Cyanomethylene)phosphoranes as Novel Carbonyl 1,1-Dipole Synthons: An Efficient Synthesis of .alpha.-Keto Acids, Esters, and Amides
摘要:
Carboxylic acids react with (cyanomethylene)triphenylphosphorane in the presence of EDCI to form cyano keto phosphoranes. The resulting ylides may then be oxidatively cleaved with ozone to form alpha,beta-diketonitriles. These highly electrophilic products may then be converted in situ to alpha-keto acids, esters, and amides.
Cyanomethylene triphenylphosphoranes of N-protected amino acids were synthesized from the corresponding N-urethane protected α-amino acid N-carboxyanhydrides (UNCAs) by reaction with cyanomethyltriphenylphosphonium chloride in good yields. These compounds are precursors of α-keto esters which are candidates for mimicking the tetrahedric transition state in enzyme inhibitors.
Azobenzene-Containing, Peptidyl α-Ketoesters as Photobiological Switches of α-Chymotrypsin
作者:Andrew J Harvey、Andrew D Abell
DOI:10.1016/s0040-4020(00)00883-8
日期:2000.12
Three photoswitchable, peptidomimetic inhibitors of oc-chymotrypsin have been synthesised. The compounds comprise an azobenzene, an alpha -ketoester and L-phenylalanine. The compounds were photoisomerised to give enriched states of the (E) and (Z) isomers and these states were assayed against alpha -chymotrypsin. The inhibitors were shown to be moderately active with switching ability of between two- and three-fold between the two isomer-enriched states. The behaviour of the inhibitors in solution was examined; specifically, their hydration and configurational stability. (C) 2000 Elsevier Science Ltd. All rights reserved.
Wasserman Harry H., Ho Wen-Bin, J. Org. Chem, 59 (1994) N 16, S 4364-4366