Dibromoalkoxythiophenes monomers (1a-d) were synthesized first by copper (I) mediated substitution of 3-bromothiophene,8 followed by a modified NBS bromination9 in THF at cryogenic temperatures. The polymerization involved treatment of 1a-d with a Grignard reagent R'MgX (e.g., MeMgBr) that resulted in magnesium bromine exchange, generating a mixture of regiochemical Grignard isomers. Upon addition of Ni(dppp)Cl2, HT-coupled regioregular polymers (2a-d) were produced.
Regioregular polythiophenes are important building blocks for new electrical applications such as field effect transistors and nanoscale materials. One method that can add complexity to the family of polythiophene is side chain elaboration. A number of functional groups can be added to the 3 position on the thiophene ring. The two major strategies are either to incorporate the desired side chain in the reactive monomer and then polymerized, or to use post polymerizstion reactions add functionality.
and also acts as a starting material for the synthesis of many ..
One method to add functional groups to the side chain is to utilize post polymerization reactions on poly[3-(6-bromoalkyl)thiophene]1. First 3-(6-bromoalkyl)thiophene) undergoes grignard metathesis reaction2,3 to produce a highly regioregular polymer (HT-Poly(3-bromohexylthiophene). Then, several functional group can be added through a series of reactions. We have successfully substituted several functionalities, such as carboxylic acids, amines, and thiols, as shown in Figure 1.
Thiophenes - Halogenated Heterocycles | Sigma-Aldrich
Heterocyclic compunds are widely distributed in nature. Many are of fundamental importance to living systems: it is striking how often a heterocyclic compund is found as a key component in biological processes. For example the nucleic acid bases, which are derivatives of the purine, namely adenine, guanine and pyrimidine, namely thymine, cystosine as being crucial to the mechanism of replication. Some purine and pyrimidines can act as antibiotics, by interference with DNA synthesis. Puromycin is an example of such an antibiotic.
22-11-2017 · Syntheses and Proper..
Heterocyclic compunds are also finding an increasing use as intermediate in organic synthesis[10-12]. Very often this is because a relatively stable ring system can be carried through a number of synthetic steps and then cleaved at the required stage in a synthesis to reveal other functional groups. For e.g. 4-chloro-5(4H)-oxazolones are useful intermediates 13 in organic synthesis. In particular hydrolytic cleavage affords α-chloro-αacylaminoketones. More ever they are the logical intermediate to prepare 4-(phospho-ranylidene)-5(4H)-oxazolones, that are very important and useful ligands.
and Thiophene Have 1 less ring ..
The search for a specific histamine H2 receptor antagonist that could potentially control gastric acid secretion, thus provide the basis for treatment for peptic ulcers, started in 1964. Having little information to guide their intial choice, the chemists used the structure of histamine for the synthesis of new compunds. Although it took a long period to discover active compounds, the work eventually resulted in 1976 was the introduction of a drug, cimetidine an imidazole derivative for the treatment of peptic ulcers 15-16.
Thiophene formation - Lawesson's reagent
On the basis of these considerations, the effects of the Arg2-Arg3 and Arg3-Nal4 peptide bonds on the activity of FC131 have been investigated through the synthesis and evaluation of the alkene analogues such as compounds 5-8 (Figure ) .