Premium
Malonic Acid Derivatives on Duty as Electron‐Withdrawing Units in Push–Pull Molecules
Author(s) -
Klikar Milan,
Jelínková Veronika,
Růžičková Zdeňka,
Mikysek Tomáš,
Pytela Oldřich,
Ludwig Miroslav,
Bureš Filip
Publication year - 2017
Publication title -
european journal of organic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 1434-193X
DOI - 10.1002/ejoc.201700070
Subject(s) - malonic acid , chemistry , barbituric acid , cyanoacetic acid , diethyl malonate , knoevenagel condensation , malonate , dimedone , malononitrile , meldrum's acid , medicinal chemistry , organic chemistry , catalysis
Based on the 2‐( N ‐piperidinyl)thiophene central donor, 32 model push–pull molecules with systematically varied malonic acid‐derived peripheral acceptors have been prepared. Further property tuning has been achieved by modifying the π‐linker and the structural arrangement (linear vs. quadrupolar D–π–A systems). Malonic acid derivatives such as cyanoacetic acid, malondinitrile, diethyl malonate, Meldrum′s acid, and N , N′ ‐dibutyl(thio)barbituric acid as well as 1,3‐diketo analogues dimedone and indan‐1,3‐dione were employed as acceptor moieties. Knoevenagel condensation with four thiophene aldehydes afforded the target chromophores in satisfactory yields. The electron‐withdrawing abilities of malonic acid acceptors were examined both by experiment including X‐ray analysis, differential scanning calorimetry, electrochemistry, and UV/Vis absorption spectroscopy, and by DFT calculations. Details of the structure–property relationships have been elucidated. According to the increasing electron‐withdrawing ability, the widely used malonic acid acceptor units can be ordered: diethyl malonate ≤ cyanoacetic acid < malondinitrile < Meldrum's acid < dimedone ≤ N , N′ ‐dibutylbarbituric acid < indan‐1,3‐dione ≤ N , N′ ‐dibutylthiobarbituric acid.