Zirconium-Mediated Reactions of Alkylpyrazines and Alkynes. Synthesis of Highly Substituted Alkylpyrazines

Article abstract of DOI:10.1021/jo00048a038

Sequential one-pot addition of alkylpyrazines, alkynes, and a proton source to a solution of Cp2Zr(Me)(THF)⁺ (1) in CH2Cl2 at room temperature affords (E)-alkenyl-substituted alkylpyrazines 2-10 in excellent yields.The regio- and stereoselectivity observed in these reactions is similar to those observed previously for related early transition metal-mediated reactions and is ascribed to steric and Si electronic effects.Conventional synthetic organic manipulation of the alkenylpyrazines provides easy access to a variety of highly substituted alkylpyrazines including tri- and tetrasubstituted alkylpyrazines 13, 17-20, dibromoalkylpyrazine 14, bromoalkylpyrazine 15, and epoxyalkylpyrazine 16.