Synthesis of potent BCRP inhibitor-Ko143

Two routes for the synthesis of potent BCRP inhibitor-Ko143 are reported. The key intermediate, 6-methoxytryptophan derivative, was synthesized by an improved procedure, ytterbium triflate-promoted coupling between 6-methoxyindole and optically active 1-benzyl-2-methyl-(S)-1,2-aziridinecarboxylate in the second protocol.

A new protocol for the synthesis of potent BCRP inhibitor-Ko143.