Cross-metathesis of unsaturated α-amino acid derivatives
Cross-metathesis of homoallylglycine derivatives with aryl- and alkyl-substituted alkenes using the ruthenium catalyst (Cy3P)2Cl2RuCHPh 1 has been achieved in 43–55 and 55–66% yield respectively. Allylglycine, vinylglycine and dehydroalanine derivatives have also been examined. Whilst cross-metathesis of allylglycine derivatives with alkyl-substituted alkenes using catalyst 1 may be regarded as a synthetically useful procedure, cross-metathesis reactions of vinylglycine and dehydroalanine derivatives using catalyst 1 are non-viable. Attachment of FmocHagOH 13 to a capped Wang resin, cross-metathesis with dodec-1-ene, and product removal from the resin gives the cross-metathesis product in 74% yield based on FmocHagOH.