Electrophilic<i>S</i>-Trifluoromethylation of Cysteine Side Chains in<i>α</i>- and<i>β</i>-Peptides: Isolation of Trifluoro-methylated<i>Sandostatin</i><sup>®</sup>(Octreotide) Derivatives
The new electrophilic trifluoromethylating 1-(trifluoromethyl)-benziodoxole reagents A and B (Scheme 1) have been used to selectively attach CF3 groups to the S-atom of cysteinesidechains of α- and β-peptides (up to 13-residues-long; products 7–14). Other functional groups in the substrates (amino, amido, carbamate, carboxylate, hydroxy, phenyl) are not attacked by these soft reagents. Depending