Willgerodt carbonyl

The conversion of a carbonyl compound by ammonium polysulphide solution into an amide with the same number of carbon atoms is known as the Willgerodt reaction. The procedure has been improved by the addition of about 40 per cent, of dioxan or of pyridine to increase the mutual solubility of the ketone and aqueous ammonium polysulphide the requisite temperature is lowered to about and the yield is generally better. 

Acetyl thiadiazole also displays enhanced reactivity in both the carbonyl and the methyl groups and enters the aldol condensation, the Mannich reaction, cyanoethylation reaction, the Willgerodt... 

These are usually prepared by the following methods (a) the Willgerodt reaction on the corresponding methyl ketone,82,98,337,485, 557 (6) hydrolysis of the corresponding cyanomethyl compound,77,337, 485,499,517,521,568 cyclization reactions (Section IV, C) (for 3-acetic acids only),143,209,310,311,313,351 or (d) the Arndt-Eistert reaction on the corresponding carbonyl chloride, which may lead directly to the acetic acid 689 or its amide.337, 568... 

The Willgerodt Reaction allows the synthesis of amides from aryl ketones under the influence of a secondary amine and a thiating agent. The mechanism involves the formation of an enamine which undergoes thiation, and the carbonyl group migrates to the end of the chain via a cascade of thio-substituted iminium-aziridinium rearrangements. 

Various condensations of 3-acetyl-l,2,5-thiadiazole (83) have been carried out which indicate a high degree of reactivity of both the carbonyl and the methyl group. The reactions investigated include the aldol condensation of 88, the Mannich reaction to 89, triscyano-ethylation to 90, and the Willgerodt-Kindler reaction to 91. The reactions proceeded under mild conditions and the normal products were obtained in good yield in each case. ... 

The uniqueness of the Willgerodt reaction lies in the ultimate formation of acids from ketones regardless of the position of the carbonyl group in the chain. 

DMF is recommended as diluent in the Ullmann synthesis of diaryls from aryl halides and as solvent for the Beckmann rearrangement of steroidal enone oximes. The Willgerodt-Kindler reaction (a carbonyl compound with a secondary amine and sulfur to give a thioamide) can be carried out in good yield at 50-60 if DMF is... 

This facile and efficient thiophene formation can be rationahzed by primary S-alkylation of 33 to give the iminium cation 35 followed by deprotonation (HBr ehmination) to the ketene-S,N-acetal 36, which cyclizes by intramolecular enamine addition to the carbonyl group (36->-37) intermediate 37 aromatizes to the products 34 by H2O elimination. Thiomorpholides (33) are easily obtained by Willgerodt-Kindler reaction of acetophenones with sulfur/morphoHne [81]. 

The name of Conrad Willgerodt is associated with a group of closely related reactions which have as a common feature the conversion of a carbonyl compound into an amide mth the same number of carbon atoms. The original process involved the reaction of an appropriately substituted alkyl aryl ketone with an aqueous solution of yellow ammonium polysulfide at an elevated temperature to form an aiyl-substituted aliphatic acid amide, ti ether with a smaller amount of the corresponding ammonium salt of the carboxylic acid. An example is the conversion of acetophenone into phenylacetamide and ammonium phenylacetate. ... 

Treatment of [ C]methyl aryl ketones with thaUium(lll) nitrate in acidic methanol (McKillop rearrangement) or with ammonium polysulfide or sulfur and morpholine at elevated temperatures (Willgerodt-Kindler reaction) provides labeled arylacetic acid derivatives. In the first case the aryl group migrates from the carbonyl position into the former methyl position, so that the label is shifted by one position. For example (Figure 6.12), in the synthesis of [6- / C]porphobilinogen the pyrrole 22 was acetylated with... 

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