Facile one-pot coupling - Aminovinylation approach to push - Pull chromophores: Alkyne activation by sonogashira coupling

Article abstract of DOI:10.1021/jo026470o

A straightforward coupling - aminovinylation sequence of terminal alkynes 1, electron-deficient heteroaryl halides 2, and secondary amines 4 furnishes highly solvochromic push-pull chromophores 5 in good yields. Semiempirical calculations (PM3) suggest that the aminovinylation proceeds in a stepwise fashion through a zwitterionic intermediate with a final rate-determining intramolecular protonation. Crucial parameters for the success of the amine addition are the relative LUMO energies and the charge distribution at the Β-alkynyl carbon atom.