Synthesis of 1,4,7-Triaza-8(S)-benzyl-3,6,13-trione
 The key steps in this scheme include the conversion of L-Phenylalanine to the corresponding Weinreb amide, which is easily reduced to L-Phenylalanal using lithium aluminum hydride.  The aldehyde is subject to Wittig conditions to extend the carbon chain by four carbons.  The resultant ester is hydrolyzed and coupled to the C-terminus protected Gly-Gly peptide.  The tripeptide undergoes hydrogenation followed by treatment with trifluoroacetic acid to deprotect the C- and N-termini, respectively, before it is cyclized to afford the desired macrocycle.
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