Formylation, dicyanovinylation and tricyanovinylation on 5-alkoxy- and 5-amino-substituted-2,2´-bithiophenes

Several donor-acceptor-substituted bithiophenes were synthesized by functionalization of the corresponding 5-alkoxy- or 5-aminobithiophenes 1 by different methods: Vilsmeier formylation, metalation followed by reaction with DMF, direct tricyanovinylation reaction using TCNE or Knoevenagel condensation starting from the corresponding 5-formyl- derivatives of 1.ICCTI/French Embassy (Technical and Scientific Cooperation Programme). Fundação para a Ciência e Tecnologia - POCTI/QUI/37816/2001, FMRH / BSAB / 134/99

A combination of friedel-crafts and lawesson reactions to 5-substituted-2,2´-bithiophenes

Gama-Keto esters (2) derivatives of thiophene were obtained from hemi-succinic esters and transformed to the corresponding amides (4). Lawesson´s treatment of 2 and 4 gave the corresponding bithiophenes (5) with alkoxy or amino substituents.Fundação para a Ci~Encia e Tecnologia. ICCTI/French Embassy - Technical and Scientific~Cooperation Programme

Donor-acceptor substituted oligothiophenes: synthesis, spectroscopic and electrochemical properties

Seven new donor/acceptor oligothiophenes 1-2 were synthesized by Stille coupling in moderate to good yields. Compounds 1-2 were completely characterized by the usual spectroscopic methods. In agreement with the electrochemical and the spectroscopic studies for this compounds the new derivatives prepared, can find application for manufacturing new materials with strong non-linear optical (NLO) properties.Fundação para a Ciência e a Tecnologia (FCT

Synthesis of donor-acceptor substituted oligothiophenes by Stille coupling

A synthesis of donor-acceptor-substituted oligothiophenes by Stille coupling is described. The 5´-estanyl derivatives, readily prepared from 5-alkoxy- and 5-amino-2,2´-bithiophenes 7 were coupled with the appropriate aryl or heteroaryl bromides to give the title compounds.Fundação para a Ciência e Tecnologia. FEDER - POCTI/QUI/37816/2001

Synthesis of 5-aryl-5´-formyl-2,2´-bithiophenes as new precursors for nonlinear optical (NLO) materials

A series of formyl-substituted 5-aryl-2,2´-bithiophenes 5 were synthesized using two different methods: Vilsmeier-Haack-Arnold reaction (VHA) or through Suzuki coupling. The synthesis of compounds 5 through the Vilsmeier-Haack-Arnold reaction, starting from inexpensive and easily available precursors such as acetophenones, gave the title compounds in low yields after four reaction steps. On the other hand Suzuki coupling of functionalized aryl boronic acids 7 and the 5-bromo-5´-formyl-2,2´-bithiophene 6 gave compounds 5 in good yields in only one step.Fundação para a Ciência e a Tecnologia (FCT

Synthesis of 1-amino-4-(2´-thienyl)phthalazine derivatives

A synthesis of 1-amino substituted 4-(2´-thienyl)-phthalazines is described from halo- derivatives of 4-(2´-thienyl)-1-(2H)-phthalazinone 3.Fundação para a Ciência e Tecnologia. FEDER - POCTI (ref. POCTI/QUI/37816/2001)

Synthesis of arylamino-thieno-oxobutanamides and reactivity studies on the cyclisation with the Lawesson´s reagent

1-aryl-2-thienyl-substituted pyrroles and 5-arylamino-2,2´-bithiophenes are synthesized by treatment of arylamino-thieno-oxobutanamides with Lawesson´s reagent. These in turn are prepared by direct amidation of 4-oxo-(2-thienyl)butanoic acid through DCC/BtOH mediated reaction.Fundação para a Ciência e Tecnologia. FEDER - POCTI/QUI/37816/2001

Arylamino-thieno-oxobutanamides under Lawesson’s conditions : competition between thienylpyrrole and bithiophene formation

1-Aryl-2-thienyl-substituted pyrroles and/or 5-arylamino-2,2´-bithiophenes were synthesized by treatment of arylaminothieno-oxobutanamides with Lawesson’s reagent. These in turn were prepared by direct amidation of 4-oxo-(2-thienyl)butanoic acid through DCC–BtOH mediated reactions.Fundação para a Ciência e Tecnologia (FCT

Electrochemical and spectroscopic studies of pyridazine derivatives

This work reports on cyclic voltammetry and spectroscopic UV-Vis investigations of some pyridazine derivatives 1-8 in dimethylformamide. In the electrochemical study, monochlorinated pyridazines 2-8 exhibit two reductions but in the case of dichlorinated derivative 1 an additional wave is seen for the reduction of the second carbon-chloride bond. The electronic absorption spectra display an intramolecular charge transfer band π-π* in the UV region of which depend substantially on the nature of both donor and acceptor moieties. These results indicate the π-electron delocalization in the conjugated system

Synthesis of formyl-thienylpyrroles : versatile building blocks for NLO materials

Several formyl-substituted 1-alkyl(aryl)-2-(2´-thienyl)pyrroles 3-7 were synthesized by functionalization of the pyrrole or thiophene ring of thienylpyrroles 2 using different methods: Vilsmeier formylation or metalation followed by reaction with DMF.Fundação para a Ciência e Tecnologi