Thiophene-2-aldehyde

Dihydro-2,5-dimethoxyfuran 824 reacts neat at 24°C with TCS 14 via the intermediate 825, the 2-trimethylsilyloxyfuran 826 (which can also be readily prepared from 5H-furan-2-one), and 827-829 to give the crystalline trimer 830 in 20% yield [21]. In the presence of aldehydes such as thiophen-2-aldehyde 831a or benzaldehyde 831b, however, 824 reacts via 832 to give the condensation products 833 a and 833 b, which are obtained in 30 and 62% yield, respectively [22, 23] (Scheme 6.11). Because it is postulated 2-trimethylsilyloxyfuran 826 is a intermedi-... 

In a variation of the usual reaction conditions for oxidising furfuraldehyde to 2-furoic acid with hypochlorite, the aldehyde was added dropwise to a 10% excess of commercial sodium hypochlorite solution at 20-25°C, but without the inclusion of additional sodium hydroxide. When aldehyde addition was almost complete, a violent explosion occurred. Subsequent investigation showed that the pH of the reaction mixture fell progressively with addition of aldehyde, and at pH 8.5 the reaction mixture erupted violently, the temperature increased by 70°C and the pH fell to 2. Similar results were seen with benzaldehyde, but not with thiophene-2-aldehyde. 

DMDS, DMTS, MT, methional, hexanethiol and thiophene 2-aldehyde. H2S and COS also make a contribution.33... 

In soft cheeses, such as Brie, Camembert, and Limburger, the following sulfur compounds were implicated 3-(methylthio)propanol, MT, DMS, DMDS, DMTS, dimethyl tetrasulfide, methyl ethyl disulfide, diethyl disulfide, 2,4-dithiapentane, 3-methylthio-2,4-dithiapentane, methional, 2,4,5-trithiahex-ane, 1,1-fe-methylmercaptodisulfide, methyl thioacetate (=methanethiol acetate), benzothiazole, methylthiobenzothiazole, methyl ethyl sulfonate, methyl methane thiosulfonate, thiophene 2-aldehyde, and H2S.34 Many of these were only present in small amounts Limburger cheese was notable for 13.2% of DMDS, 0.5% of methyl thioacetate, and 0.8% of DMTS. 

King, W. J., and F. F. Nord Preparation of Thiophene-2-Aldehyde and Some... 

A]thiophene, and with polymeric chloroacetaldehyde, it leads to 5-ethylthieno[2,3-A]thiophene-2-aldehyde, characterized as its 2,4-dinitro-phenylhydrazone. 

Thiophene-2-aldehydes or 2-ketones undergo the Stobbe reaction, and the products 127 are cyclized by Ac20-Na0Ac to the 6-carboxylic esters 128... 

Reactions of Thiophen Aldehydes and Ketones.—The synthesis of bis-(4-methylpent-3-enyl)thiophens was achieved by applying the Wittig reaction to (106). A convenient method for the synthesis of (2-thienyl)ethylene oxide from thiophen-2-aldehyde and a sulphur ylide has been worked out. From 2-thenil and diethyl ketone, (107) was prepared, and its Diels-Alder reactions have been studied. The reaction of (108) with different Grignard reagents has been... 

Further work on the use of the gcm-dimorpholine derivative of 2-thienylgly-oxal for the synthesis of gem-di(acylamino)- and other derivatives has appeared. In connection with work on surfactant complexes of ruthenium, thiophen-2-aldehydes were condensed with 4,4 -dimethyl-2,2 -bipyridyls. From the easily available 2,3,4-trichlorothiophen, the 5-formyl- and 5-acetyl-derivatives have been prepared, and from them a large number of derivatives. ... 

The anisotropy of the second carbonyl group increases the downfield shift of the 3-hydrogen by more than 0.5 p.p.m. compared with simple carbonyl derivatives such as thiophen-2-aldehyde. 

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