| Abstract
| - Synthetic approaches to the lantibiotics, a family of thioether-bridged antimicrobial peptides, requireflexible synthetic routes to a variety of orthogonally protected derivatives of lanthionine 1. Themost direct approaches to lanthionine involve the reaction of cysteine with an alanyl β-cationequivalent. Several possibilities exist for the alanyl β-cation equivalent, including direct activationof serine under Mitsunobu conditions: however, the low reactivity of sulfur nucleophiles in theMitsunobu reaction has previously precluded its use in the synthesis of the lantibiotics. We reporthere a new approach to the synthesis of protected lanthionine, using a novel variant of the Mitsunobureaction in which catalytic zinc tartrate is used to enhance the nucleophilicity of the thiol. In thecourse of these studies, we have also demonstrated that the synthesis of lanthionine from trityl-protected β-iodoalanines is prone to rearrangement, via an aziridine, to give predominantly trityl-protected α-iodo-β-alanines, and hence norlanthionines, as the major products.
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