Dithieno 3,4-6 3 ,4 -</ thiophene

Many substituted thiophenes have also been electrochemically polymerised [19,54,399-405] (Table 4) as have thiophene dimers [21,37,55,251,400,406], trimers [21, 83,407], and tetramers [256,406], with the thiophene dimer giving rise to higher quality films than does the monomer [37, 395,408]. Several polycyclic monomers including a thiophene ring have also been polymerised [408-416], as have a series of compounds consisting of two thiophene rings linked by a polyene chain (Fig. 23c). The polymerisation of dithieno-thiophene (Fig. 23d) results in a polymer which shows remarkable similarity to polythiophene in its properties [409,410,414],... 

Electron-rich dithieno(thiophene) groups are also effective in increasing the value of the closed-ring form (Scheme 4). 

S. Luzzati, M. Basso, M. Catellani, C. J. Brabec, D. Gebeyehu and N. S. Sariciftci, Photo-induced electron transfer from a dithieno thiophene-based polymer to Ti02, Thin Solid Films, 403, 52-56 (2002). 

The naming of these three heterocyclic fused (5 5 5) ring systems has been carried out according to the IUPAC system of nomenclature. Some examples are given as follows compound la (Table 1) is named (3-hydroxy-4-methoxyphenylthieno[2,3-3]pyrrolizin-8-one. Compound 15a (Table 2) is dithieno[3,2-3 2, 3 - 1thiophene. Compound 23a (Table 2) is dithieno[3,2-3 2, 3 - 1pyrrole. Compound 20a (Table 2) is dithicno[3,2-3 2, 3 -r/]thiophene-4,4-dio ide. Compound 13b (Table 2) is 3,4-dimethyldithieno[3,2-3 2, 3 -i/]thiophene-7,7-dioxide. Compound 38 (Table 4) is fM, r, r-10-azatricyclo[5.2.1.01 10]deca-2,5,8-triene. Compound 39 (Table 4) is cis,cis, m-10-azatricyclo[5.2.1.01 10]deca-2,8-diene. The nomenclature of compound 40 (Table 4) is 1,4,7 triaza tricy-clo[5.2.1.01,10]decane. 

Synthesis of dithieno[2,3-A2,3-,7]thiophene derivatives 122 has been accomplished through the Heck reaction of 3-(4-bromo-2-thienyl)acrylic acid 302 to afford 3-(2,4-thienylene)diacrylic acid 303 which was cyclized with thionyl chloride and a catalytic amount of pyridine to the dichloride 120 in 75% yield (Scheme 56) <2005MOL279>. 

An improved synthesis of dithieno[3,2-A2, 3 -<7]thiophene 15a has been achieved from 2,3-dibromothiophene 304 (Scheme 57). Lithiation of 2,3-dibromothiophene 304 using -butyllithium followed by oxidative coupling with cupric chloride provided 3,3 -dibromo-2,2 -bithiophene 305 in 79% yield. Treatment of 305 with 2 equiv of -butyllithium in ether at —78 °C under nitrogen for 40 min and then adding benzenesulfonic acid thioanhydride and leaving the reaction mixture to reach room temperature afforded dithieno[3,2-A2, 3 -<7]thiophene 15a in 70% yield <2002TL1553>. 

The synthesis of dithieno[3,2-3 2, 3 -<7]thiophene 15a has also been accomplished using a combination of the methods described by De Jong et al. and Brandsma . In this approach, 3-bromothiophene 298 was lithiated and the 3-lithiothiophene 308 species reacted with sulfur dichloride to give di(3-thienyl)sulfide 309. Ring closure of 309 was effected using -butyllithium followed by addition of cupric chloride to yield dithieno[3,2-3 2, 3 -. 

A general synthesis of dibenzo-annelated dithieno[3,Z-b Z, 3 - thiophene 18 has been reported from bis(o-hydro-xyl)diacetylenes. This cyclization constructs a fused tricyclic skeleton in one pot. The subsequent dechalconization with copper powder produces a series of thiophene and selenophene-based heterocenes (Scheme 64) <20050L5301>. 

Thus, many polymers with different conductivity were synthesized. To cite a few, these are polythiophene [158], 3-methylthiophene [159], polymers of 3-thiophene-acetic acid and methyl 3-thiophene-acetate [160], poly(2,5-thienylenevinylene) [161], poly(benzo[h]-thiophene) [162], poly(naphto[2,3-c]thio-phene) [163], poly(dithieno[3,2-h 2, 3 -fii]-thiophene) [164], poly(3- -hexylthiophene)... 

A new class of photochromic diarylethenes containing thieno[3,2-b] thiophenes, dithieno[3,2-b 2, 3 -d]thiophene (08CC5203), and dithieno [3,2-fc 2, 3 -d]pyrroles (09CEJ10005) with photoswitchable luminescence properties were synthesized by Suzuki cross-coupling reactions (Scheme 48). 

Another method for e preparation of aryl w-dimethoxyethyl sulfides was described by Pandya and Tilak. The procedure consists in allowing aryl lithium derivatives to react with 2,2,2, 2 -tetramethoxy-diethyl disulfide. Subsequent cyclization of the sulfides by polyphos-phoric acid yields 2-35% of condensed thiophenes and thiopyrans. By this method, thienothiophene 1 was prepared from 2-thienyllithium [Eq. (12)] and the previously unknown dithieno[2,3-6 3, 2 -i/]thiophene (5) was obtained from thienyl-2,5-dilithium. The possibility of synthesizing a heterocyclic analog (25) of pentacene from dithieno[2,3-6 3 2 -[Pg.130]

Zwanenburg and Wynberg also proposed another route to the thienothiophene (112). 2,5-Dibromo-3,4-bisbromomethylthiophene (116) was cyclized with sodium sulfide to give 4,6-dibromo-l f,3/f-thieno[3,4-c]thiophene (117) in 60% yield 117 was then reduced to thienothiophene (112). l,3,7,9-Tetrabromo-4i/,67f,10.H, 12ff-dithieno-[3,4 C 3, 4 -/i][l,6]dithiecin (118) (18%) was also formed during the ring closure. Oxidation of thienothiophene (117) followed by reduction by zinc in acetic acid gave l/f,3H-thieno[3,4-c]thiophene 2,2-dioxide (119). ... 

The first compound of this series, dithieno[2,3-6 3, 2 -rf]thiophene (5), was prepared as mentioned above by Pandya and Tilak, who cyclized 2,5-bis((y-dimethoxyethylthio)thiophene with polyphosphoric acid. 

The reduction of thieno[3,2-6]thiophene-2,5-diaIdehyde or dithieno-[3,2-i 2, 3 -d]thiophene-2,6-dialdchyde with potassium in tetra-hydrofuran or 1,2-dimethoxyethane yields the corresponding anion-radicals, the ESR of which give information on the conformation of similar carbonyl compounds.Cation-radicals have also been studied (see Section IV). 

By DMF and phosphorus oxychloride, dithieno[3,2-6 2, 3 -d]-thiophene (6) was converted into the 2-formyl derivative in 93% yield. The production of 2,6-diformyldithieno[3,2-6 2, 3 -[Pg.193]

This, after 1,3,6,8-tetraazapyrene, was only the second example of obtaining both a negative and a positive radical from the same heterocyclic compound. Attempts to generate radical-ions from other condensed thiophenes succeeded only with dithieno[2,3-d 2, 3 -radical-cation [HFSC 0.42 (2H), 2.36 (IH), and 2.98 (IH) Gauss]. 

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