Crystal structure of ethyl 3-(4-chlorophenyl)-5-[(E)-2-(dimethylamino)ethenyl]-1,2-oxazole-4-carboxylate

In the title compound, C16H17ClN2O3, two molecules, A and B, with different conformations, comprise the asymmetric unit. In molecule A, the C=O group of the ester points away from the benzene ring [C—C—C=O = −170.8 (3)°], whereas in molecule B, it points back towards the benzene ring [C—C—C=O = 17.9 (4)°]. The dihedral angles betweeen the oxazole and benzene rings also differ somewhat [46.26 (13) for molecule A and 41.59 (13) for molecule B]. Each molecule features an intramolecular C—H...O interaction, which closes an S(6) ring. In the crystal, the B molecules are linked into [001] C(12) chains by weak C—H...Cl interactions

Rh(II)-mediated domino [4+1]-annulation of alpha-cyanothioacetamides using diazoesters: A new entry for the synthesis of multisubstituted thiophenes

A new approach towards the synthesis of multisubstituted thiophenes is elaborated based on Rh(II)-catalyzed domino reactions of acyclic diazoesters with α-cyanothioacetamides. It provides a way for the preparation of 5-amino-3-(alkoxycarbonylamino)thiophene-2-carboxylates, 2-(5-amino-2-methoxycarbonylthiophene-3-yl)aminomalonates and (2-cyano-5-aminothiophene-3-yl)carbamates with the preparative yields of up to 67%. It was also shown that α-cyanothioacetamides easily interact with dirhodium carboxylates to give rather stable 2:1 complexes, resulting in an evident decrease in the efficiency of the catalytic process at moderate temperatures (20–30 °C)

Copolymerization of zinc-activated isoindigo- and naphthalene-diimide based monomers: an efficient route to low bandgap pi-conjugated random copolymers with tunable properties

The present work aims at the extension of the scope of a recently discovered polycondensation of AB-type anion-radical monomers. To this end, we investigate the polymerization of isoindigo-based monomer and its copolymerization with the naphthalenediimide-based monomer. Although polycondensations of parent naphthalenediimide- and perylenediimide-based monomers involve chain-growth mechanism, we found that the corresponding isoindigo-based monomer polymerizes in a step-growth manner under the same reaction conditions. In contrast to Stille, Suzuki and direct arylation polycondensations which require prolonged stirring at high temperatures, the polymerization approach we employed in this study proceeds fast at room temperature. It was found that near statistical copolymerization of isoindigo-based anion-radical monomers with corresponding naphtalenediimide-based monomers proceeds smoothly resulting in a library of copolymers with varying composition and properties depending on the ratio of the monomers