Conjugate addition of potassiumtrifluoro(organo)borates 2 to dehydroalanine derivatives 1, mediated by a chiral rhodium catalyst and in situ enantioselective protonation, afforded straightforward access to a variety of protected alpha-amino esters 3 with high yields and enantiomeric excesses up to 95%. Among the tested chiral ligands and proton sources, Binap, in combination with guaiacol (2-methoxyphenol)
Novel Cyclic Tripeptides and Substituted Aromatic Amino Acids via Ruthenium-Activated S<sub>N</sub>Ar Reactions
作者:Christopher W. West、Daniel H. Rich
DOI:10.1021/ol991084n
日期:1999.12.1
[formula: see text] Chlorophenylalanines eta 6-complexed to ruthenium undergo SNAr reactions with a variety of nucleophiles to form substituted phenylalanines exemplified by 4b. Extension of these reactions to intramolecular ruthenium-activated SNAr cyclizations led to three novel cyclic tripeptide systems (exemplified by 17 and 20).
Functionalization of Aromatic Amino Acids via Direct C−H Activation: Generation of Versatile Building Blocks for Accessing Novel Peptide Space
作者:Falco-Magnus Meyer、Spiros Liras、Angel Guzman-Perez、Christian Perreault、Jianwei Bian、Keith James
DOI:10.1021/ol1015674
日期:2010.9.3
Functionalized α-amino acid building blocks have been prepared in good yield with high regiocontrol and preservation of stereochemistry via iridium-catalyzed borylation of suitably protected aromatic α-amino acid derivatives. The utility of these systems in peptide couplings and Suzuki reactions has been demonstrated.