Patent ID: 8569452

Claim:
A method of making the following compound: wherein R 1 , R 2 , R 3 are each independently selected from the group consisting of hydrogen, alkyl, cycloalkyl, heterocycloalkylaryl, heteroaryl, acyl, acylalkyl, carboxy, carboxamido, trialkylsilyl, aryldialkyl, hydroxy, alkoxy, aryloxy, heteroaryloxy, chloro, bromo, fluoro, iodo, thio, alkylthio, arylthio, acyclthio, amino, alkylamino, dialkylamino, acylamino, arylamino, diarylamino, carboxamido; and wherein the method comprises the following steps: a) synthesizing a linear heptapeptide on a resin; b) cleaving the linear heptapeptide from the resin; c) performing head-to-tail coupling on the heptapeptide to produce a cyclic peptide; d) forming a thioether by direct indole thionation thereby making the compound.