Palladium-catalyzed N-(2-pyridyl)sulfonyl-directed C(sp<sup>3</sup>)–H γ-arylation of amino acid derivatives
作者:Nuria Rodríguez、Jose A. Romero-Revilla、M. Ángeles Fernández-Ibáñez、Juan C. Carretero
DOI:10.1039/c2sc21162a
日期:——
The direct Pd-catalyzed γ-arylation of amino acid esters bearing a removable N-(2-pyridyl)sulfonyl directing group is described. A variety of N-(2-pyridyl)sulfonamide amino acid derivatives, including α-quaternary amino acid and β-amino acid substrates, react with iodoarenes in the presence of Pd(OAc)2 to provide γ-arylated products in synthetically useful yields. An unprecedented remote C(sp3)âH arylation of dipeptides is presented, illustrating the compatibility of the method with the presence of the peptidic bond. The process occurs without racemization at the Cα center and the auxiliary controlling group can be easily installed and removed in the amino acid backbone. A bimetallic PdII γ-metalated complex has been isolated and characterized showing the key role exerted by the (2-pyridyl)sulfonyl unit.
Experimental and computational studies on the mechanism of the Pd-catalyzed C(sp<sup>3</sup>)–H γ-arylation of amino acid derivatives assisted by the 2-pyridylsulfonyl group
The Pd(OAc)2-catalyzed γ-arylation of aminoacidesters bearing a removable N-(2-pyridyl)sulfonyl directing group via C(sp3)–H activation provides a direct method to form functionalized aminoacids without racemization at the α-C and with a high degree of stereoselectivity. The present mechanistic studies suggest that the reaction proceeds via a catalytically active monomeric species, and that the