Total synthesis of cyclosporine: access to N-methylated peptides via isonitrile coupling reactions.

Recent developments in the use of isonitriles to furnish secondary and tertiary amide bond formations have been applied to a novel total synthesis of the important cyclic polypeptide cyclosporine A. Specifically, the disclosed synthetic route demonstrates the utility of microwave-mediated carboxylic acid isonitrile couplings, thioacid isonitrile couplings at ambient temperature, and isonitrile-mediated couplings of carboxylic acids and thioacids with amines to form challenging amide bonds.