Preparation of push-pull type chromophores via nitrothiophene induced Michael type reaction of alkynes
摘要:
Nitrothiophene activates a neighboring alkyne to undergo Michael addition with dialkylamines and methanol to afford push-pull type chromophores. These compounds exhibit a large positive solvatochromism. The olefinic moiety in (Z)-(((5-nitrothien-2-yl)methylene(ferrocenyl)methyl)diethylamine (14) can be converted to an alpha-diketone. (C) 1999 Elsevier Science Ltd. All rights reserved.
Facile One-Pot Coupling−Aminovinylation Approach to Push−Pull Chromophores: Alkyne Activation by Sonogashira Coupling
摘要:
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.