RESUMO
A one-pot transformation of biaryl dicarboxylic acids to (NH)-phenanthridinone derivatives based on a Curtius rearrangement and subsequent basic hydrolysis was developed. This method is also applicable for the preparation of optically active amide-functionalized [7]helicene-like molecules. Furthermore, aza[5]helicene derivatives with a phosphate moiety were isolated as a product of the Curtius rearrangement step in the case of substrates that bear chalcogen atoms. The stereostructures of these products, revealed by X-ray diffraction analysis, suggested that chalcogen-bonding and pnictogen-bonding interactions might contribute to their stabilization. The configurational stability of the helicene-like molecules and their chiroptical properties were further investigated.
Assuntos
Calcogênios , Compostos Policíclicos , Amidas/química , Calcogênios/química , Ácidos Dicarboxílicos , Compostos Policíclicos/químicaRESUMO
Axially chiral binaphthothiophene dicarboxylic acid was prepared as a novel functionalized chiral dicarboxylic acid. The crystal structures of both the racemic form and its salt with chiral diamine revealed the intramolecular S···O interactions (chalcogen bonds) between the sulfur in the naphthothiophene rings and the oxygen of the carboxy groups. The negative-positive and the positive-negative Cotton effects from longer to shorter wavelengths were observed for (R)- and (S)-enantiomers, respectively, in the circular dichroism (CD) spectra.
Assuntos
Ácidos Dicarboxílicos/química , Tiofenos/química , Ácidos Dicarboxílicos/síntese química , Modelos Moleculares , Estrutura Molecular , Estereoisomerismo , Tiofenos/síntese químicaRESUMO
The scope and limitations of the platinum catalyzed 7-endo cyclization of internal alkynyl amides were investigated. Substitution of the alkyne with an aryl group gave better results, presumably because it stabilized the transition state. Applying the reaction to a secondary amide, the caprazamycin core was successfully synthesized from commercially available material in eight steps.