Phthalimide as a chromophoric tag in the circular dichroism determination of absolute configuration of α-aminoacid amides and dipeptides. A case of a dipeptide isostructurality
作者:P Skowronek、A Katrusiak、J Gawroński
DOI:10.1016/s0040-4020(02)01362-5
日期:2002.12
amides and methyl amides as well as N-phthaloyl dipeptide methyl esters give Cotton effects of opposite signs at around 220 and 240 nm. The signs of these Cotton effects are directly correlated with the absolute configuration of the N-phthaloyl substituted stereogenic center: for l-configuration the Cottoneffect at 240 nm is positive and the Cottoneffect at 220 is negative. The X-ray analysis shows that
site-selective C(sp3)–H chlorination of oligopeptides based on an N-chloropeptide strategy. N-chloropeptides, which are easily prepared from the corresponding native oligopeptides, are smoothly degraded in the presence of an appropriate copper catalyst, and a subsequent 1,5-hydrogen atom transfer affords γ- or δ-chlorinated peptides in excellent yield. A wide variety of aminoacid residues can thus be site-selectively