Facile one-pot coupling-aminovinylation approach to push-pull chromophores: alkyne activation by sonogashira coupling.
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 beta-alkynyl carbon atom.
Karpov
Alexei S
AS
Organisch-Chemisches Institut der Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany.
Rominger
Frank
F
Müller
Thomas J J
TJ