Thiophene-based

TicarcHHn [34787-01-4] (SB) (52) is a significant penicillin antibiotic that incorporates the thiophene ring system. A number of routes to the required intermediate, 3-thiophenemalonic acid [21080-92-2] have been used over the years. Those from thiophene-based starting materials have involved 3-methylthiophene and 3-bromothiophene. 

Dyestuffs. The use of thiophene-based dyestuffs has been largely the result of the access of 2-amino-3-substituted thiophenes via new cycHzation chemistry techniques (61). Intermediates of type (8) are available from development of this work. Such intermediates act as the azo-component and, when coupled with pyrazolones, aminopyrazoles, phenols, 2,6-dihydropyridines, etc, have produced numerous monoazo disperse dyes. These dyes impart yeUow—green, red—green, or violet—green colorations to synthetic fibers, with exceUent fastness to light as weU as to wet- and dry-heat treatments (62-64). 

Hydrogenation of olefin with thiophene-based ligands. 

More recently, these authors have reported the synthesis of a new thiophene-based analogue of (I ,i )-Me-DuPHOS called UlluPHOS. The facial recognition and enantioselection associated with ruthenium complexes of UlluPHOS and Me-DuPHOS were shown to be similarly high in various hydrogenations of p-keto esters (Scheme 8.32). The most important difference between these two ligands was found by comparing the reaction rates. Indeed, the authors have observed that the use of UlluPHOS considerably increased the activity of the complexes. 

Since thiophenes are regarded as being good substructures for organic electronic materials, phosphorylthiophenes are taken as reference compounds for thiophene based materials [45] and phosphorylthiophenes such as 16 are employed as synthetic intermediates for phosphoryl substituted organic electronic materials such as oligothiophenes or thienylene bridged donors (Scheme 26) [46],... 

Thiophene is the typical model compound, which has been extensively studied for typifying gasoline HDS. Although, some results are not completely understood, a reaction network has been proposed by Van Parijs and Froment, to explain their own results, which were obtained in a comprehensive set of conditions. In this network, thiophene is hydrodesulfurized to give a mixture of -butenes, followed by further hydrogenation to butane. On the considered reaction conditions, tetrahydrothiophene and butadiene were not observed [43], The consistency between the functional forms of the rate equations for the HDS of benzothiophene and thiophene, based on the dissociative adsorption of hydrogen, were identical [43,44], suggesting equivalent mechanisms. 

The same group of authors has recently reported a combination of various palladium- and copper-catalyzed Suzuki, cyanation, and Ullmann condensation reactions for the synthesis of thiophene-based selective angiotensin II AT2 receptor antagonists (Scheme 6.24) [55],... 

A range of potent biaryl hydroxamates has been claimed, certain of which exhibit excellent selectivities for HDAC8 versus HDAC1. These compounds include thiophene-based 19 with enzyme IC50s of 41 nM versus >100 gM, respectively [52]. 

B. Liu, W.-L. Yu, Y.-H. Lai, and W. Huang, Synthesis, characterization, and structure-property relationship of novel fluorene-thiophene-based conjugated copolymers, Macromolecules, 33 8945-8952, 2000. 

E. Lim, B. Jung, and H. Shim, Synthesis and characterization of a new light-emitting fluorene-thieno[3,2-6]thiophene-based conjugated copolymer, Macromolecules, 36 4288-4293, 2003. 

G. Barbarella, L. Favaretto, M. Zambianchi, O. Pudova, C. Arbizzani, A. Bongini, and M. Mastragostino, From easily oxidized to easily reduced thiophene-based materials, Adv. 

A novel thiophene-based molecular scaffold that could be used for optical in vivo imaging of protein aggregates was recently reported by Aslund et al. [36]. This chemically defined anionic pentameric thiophene derivative, p-FTAA (Fig. 21a), could be utilized for direct in vivo detection of A [S deposit in the brain of a transgenic mouse model with AD pathology. The deposits were easily visualized by two-photon... 

Synthesis. The first known thiophene-based metal dithiolenes were reported by Gol dfarb and Kalik in 1968." These consisted of the nickel and copper complexes of 2,3-thiophenedithiolate produced from ethyl 3-thienyl sulfide as shown in Scheme 1. Both complexes were reported as black, high melting solids and were thought to be the neutral bis(2,3-thiophenedithiolate) species. 

Iron(iii) chloride has been used as an oxidant to catalyze the cyclization of acyclic precursors to highly derivatized benzodithiophenes <2006TL1551>. Thus, thiophene-based polycyclic aromatics have been produced in high yield (Equation 75). 

An interesting approach for the synthesis of enantiopure thiophene-based[7]helicene has been described which utilizes an intramolecular McMurry coupling using low-valent titanium as the key step <2004CEJ6531>. It was found that yields of the product varied widely due to the formation of varying quantities of the intermediate diol and desilylated starting material. 

The key step in the preparation of a novel class of condensed thiophene based GABA receptor inverse agonists was the cross-coupling of the bromo derivative of the parent system. The 2-pyrrolyl substituent, for example, was... 

Over the last few decades there has been much interest in the thiophene-based systems and considerable effort has been expended in many laboratories on various aspects of their chemistry, including synthesis, structural studies and theoretical calculations and predictions. X-Ray analysis of the crystal structures of thieno[3,2-6]thiophene (3) (49AX356), selenolo[3,2-6]selenophene (4) (69AX(B)1374) and thieno[3,2-6 jfuran derivative (5) (79CC366) have been reported. 

Fig. 35 Examples of (a) mesogenic dibenzoylhydrazines 132a-c (77° C) [122] and (b) thiophene based 71-conjugated aromatics [250-255]...

Random copolymers 596a-d synthesized by Yamamoto coupling of a fluorene and thiophene-base (02MI199 02MM1224). 

All the copolymers showed similar absorptions with Lmax at 470 nm, which was more intense for polymers with higher thiophene content. In contrast, their emission colors were progressively red shifted with increasing thiophene-based comonomer content. Copolymer 596a emitted bright red light (620 nm) with reasonably high photoluminescent quantum yields (34-69%). 

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