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Native Chemical Ligation at Phenylalanine

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journal contribution
posted on 22.08.2007, 00:00 by David Crich, Abhisek Banerjee
Synthesis of erythro-N-Boc-β-mercapto-l-phenylalanine enables native chemical ligation at phenylalanine. In the form of the S-ethyldisulfanyl derivative, the N-Boc amino acid is used to cap a tetrapeptide generated by Fmoc-SPPS. The native chemical ligation with C-terminal thioesters then occurs successfully and is followed by selective desulfurization of the benzylic C−S bond. The method is applied to the synthesis of LYRAMFRANK, thereby establishing compatibility with the reactive side chains and the ability to ligate other than glycine.