Abdo, Nabiha I. published the artcilePalladium-Catalyzed Direct C-H Arylation of Thieno[3,4-b]pyrazines: Synthesis of Advanced Oligomeric and Polymeric Materials, COA of Formula: C4Br2N2O4S, the publication is European Journal of Organic Chemistry (2012), 2012(28), 5540-5551, S5540/1-S5540/37, database is CAplus.
The first examples are reported of an efficient direct regioselective direct C-H arylation of thieno[3,4-b]pyrazine (TP) and its 2,3-di-Me derivative with bromoalkylthiophenes (BATs), under Heck exptl. conditions using Pd(OAc)2/Bu4NBr as the catalytic system, giving rise to a variety of valuable aryl-substituted thienopyrazines. The obtained results suggested that the 2-position of the TP moiety is less reactive towards C-H arylation than the 5- and 7-positions. Moreover, the 3-position of the TP moiety showed almost no significant reactivity when all other positions were arylated. The C-H arylation of 2,3-dimethyl-TP with an excess amount of BATs proceeded smoothly, affording the corresponding diarylated thienopyrazine derivatives in excellent yields, without any addnl. products. Compared to usual cross-coupling reactions, the present synthetic methodol. has been used to prepare interesting donor-acceptor π-conjugated polymeric materials in a facial manner in a simple way. Microwave-assisted polymerization proved to be efficient for obtaining reasonable mol. weight copolymers ranging from 18.8 to 24.3 kg mol-1. Incorporating the thienopyrazine unit into polyhexylthiophene chains affected the photophys. and electrochem. properties. The optical band gaps were estimated to be in the range of 1.63-1.06 eV. All copolymers exhibited a diffraction peak at around 2θ = 5.72° corresponding to a d spacing of 15.43 Å, which was assigned to an interchain spacing between polymer main chains similar to that found in P3HT. Moreover, a peak around 2θ = 23.09 (3.84 Å) was also observed and is believed to be related to π-π stacking of the polymer backbones.
European Journal of Organic Chemistry published new progress about 52431-30-8. 52431-30-8 belongs to bromides-buliding-blocks, auxiliary class Liquid Crystal &OLED Materials, name is 2,5-Dibromo-3,4-dinitrothiophene, and the molecular formula is C4Br2N2O4S, COA of Formula: C4Br2N2O4S.
Referemce:
https://en.wikipedia.org/wiki/Bromide,
bromide – Wiktionary