Thiophene diformyl

Mass spectrometry and gas-liquid chromatography showed 3-formylthieno[2,3-6]thiophene (0.2%) in the crude product from While diformyl derivatives were not observed from 2 with two equivalents of DMF, small quantities of the diformyl derivatives were detected by mass spectrometry in the case of thienothiophene l. Italian researchers obtained 2,S-diformylthieno[3,2-Mthiophene by the action of n-butyllithium and dimethyl formamide on 2,5-dibromothieno[3,2-2>]-thiophene. ... 

The 2,5-diacetyl derivative of thiophene has been examined (71CR(B)1366) and contains 50% of the mixed (2c,5t + 2t,5c) form, close to the 40% found for the corresponding diformyl derivative. 

The first synthetic approach to 21-monoheteroatom-substituted porphyrins involved a "3+1" condensation approach using 2,5-diformyl furan 219 (X=0) or thiophene 219 (X=S) and tripyrrane 220 (Y=NH), to obtain meso-unsubstituted 21-oxa 221 (X=0, Y=NH) or 21-thia 221 (X=S, Y=NH) porphyrins (Scheme 89) (1970JCS(D)807,1971JCS(C)3681,1969JCS(CC)1480). 

In addition to the above, two air-stable, crystalline 20-Tt-electron dithia-A, A -dihydroporphycene derivatives, specifically 3.51 and 3.52, have been prepared recently by Neidlein and coworkers (Scheme 3.1.8). As could perhaps be imagined, these species were also prepared via a low-valent titanium-mediated reductive coupling procedure, involving the diformyl thiophene-pyrrole 3.50, carried out in the presence of TiCU and Zn. Interestingly, it is not only 3.51 but also 3.52 that is isolated under these conditions. This stands in direct contrast to what is observed in the case of the mixed furan-pyrrole coupling discussed above (Scheme 3.1.7) there, only one of the two possible isomers was isolated. 

Dehydrogenations of piperazines to pyrazines have been described in Section II.6, and the conversion of piperazine over catalysts (e.g., CuO) to give mostly pyrazine (90-94%) has been studied (1718). The oxidation of 1,4-diphenylpiperazine with manganese dioxide in chloroform at 20° to yield A, A -diformyl-A(, -diphenyl-ethylenediamine has been reported (1719). Formylpiperazines have been reported as formylating agents. Thiophene, 1,4-diformylpiperazine, and phosphoryl chloride are reported to give 2-formylthiophene (1720). 

Many macrocyclic SBs have been prepared by condensation of different dicarbonyl precursors (head units (55), see Scheme 16) such as 2,6-diformylpyridine (56, R = H, 56a), 2,6-diacetylpyridine (56, R = CH3, 56b), 2,6-diformyl-4-Z-phenol (57, Z = C1- 57a, CH3-, 57b), 2,6-diacetyl-4-Z-phenol (57, Z = C1—, 57c, Z = CH3, 57d) thiophene-2,5-dicarbaldehyde (58), furan-2,5-dicarbalde-hyde (59), pyrrole-2,5-dicarbaldehyde (60), 2,6-diformyl-4Z-thiophenol (61, Z = CH3, 61a Z Bu1, 61b) or /3-triketones (62) with a wide range of different diamines (lateral chains). The majority of SB macrocycles are symmetrical and contain either phenol or pyridine as head units. Asymmetrical SB macrocycles have also been prepared. The SB macrocycles are designated [1 + 1] and [2 + 2] depending on the number of head and lateral units present (see Scheme 17). With certain precursors (i.e., 2,6-diacetylpyridine and l,3-diamino-2-hydroxypropane) [3 + 3] and [4 + 4] macrocyclic complexes have also been synthesized.177-179 The [2 + 3] condensation products have also... 

Mit uberschiissigem Chlormethylen-dimethyl-iminium-dichlorphosphat kann 2-Acet-amino-thiophen zum 2-Acetamino-3,5-diformyl-thiophen (94%) diformyliert werden500. 2-Fo rmyl-se le nop hen (70-74%) erhalt man mit Chlormethylen-dimethyl-iminium-di-chlorphosphat bzw. N-Chlormethylen-N-methyl-N-phenyl-iminium-dichlorphosphat unter ahnlichen Bedingungen wie das Thiophen-Derivat503-505. 

Diformyl-thiophen308 5,8 g (43 mmol) 3,4-Dicyan-thiophen werden mit 18 ml (10% OberschuG) Bis-[2-methyl-propyl]-aluminiumhydrid wie oben reduziert. 

Macrocyclic Thiophens. - Novel macrocyclic Schiff-bases (161), containing thiophen, have been prepared by the non-template condensation of a,co-amino-ethers with thiophen-2,5-dicarbaldehyde. Silver complexes were prepared and crystal structures were determined both for some macrocycles and for a silver complex. In attempts to prepare bridged thia[17]-annulenes, (162) was prepared through the reaction of 2,5-dichloromethyl-thiophen with p-carboxytoluene-a-thiol. Transformation of the carboxyl groups of (162) into bromomethyl, followed by reaction with sodium sulphide,gave (163). The Wittig reaction of 3,4-diformyl-2,5-dimethylthiophen... 

For 2,5-diformyl derivatives, the 2-cis,5-cis form predominates although 20-30% of the cis,trans form is also detected <72JCS(P2)755>. There is however less than 1% of the tram,trans conformer. For thiophene-2,3-dicarbaldehyde, the cis,cis form is preferred over the trans,trans by a factor of 2 1 <71TL145>. 

Palladium-mediated oxidative arylation of thiophene has also been reported <8SJ0CS272>. Thus, treatment of 2-formylthiophene with palladium acetate in a mixture of acetic add and benzene gave 2-formyl-4-phenylthiophene (30%), 2-formyl-5-phenylthiophene (5%) and 5,5 -diformyl-2,2 -bithienyl (16%). It has been suggested that preliminary palladation of benzene would lead to 4-phenylation of the thiophene, while palladation of the thiophene would produce the 5-phenylated product. 

Mono- (266) and diformyl derivatives 267, which were prepared by formylation of l,3,4,6-tetrakis(isopropylthio)thieno[3,4-c]thiophene (268) with the Vilsmeier reagent, also proved to be rather stable (76TL2581). 

Diformyl thiophen reacts with nitromethane in the presence of alkali to give the nitronate salt (151), which upon acidification with strong acid gives a mixture of (152) and (153), which in turn can easily be transformed to the 2-indanone analogue (154). ... 

Thiophen Analogues of Porphyrins.—During recent years several groups have become interested in thiophen analogues of porphyrins and related compounds. The 2 + 2 principle was used in the reaction of the 5,5 -dilithio-di-2-thienylmethane derivative (210a) with the corresponding diformyl... 

Thiophen Analogues of Tropylium Ions and Related Compounds.—Condensation of 3,4-diformyl-2,5-dimethylthiophen with acetone or diethyl ketone yields the tropone (496). The reaction with acetone differs from that of phthalaldehyde, which only yields indanones." The reduction of (496) with LiAlH, and also the reaction with Grignard reagents, gave ethereal solutions of alcohols, which with HCIO4 gave the deep-blue tropylium-type perchlorates (497), which are stable in acetic acid." " The carbonium ion (497 R = Me) is less stable than the tropylium ion itself, as a mixture of (498 R = Me) and (499 R = Me) is obtained upon reaction with cyclo-... 

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