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The Fischer indole synthesis is a chemical reaction that produces the aromatic heterocycle indole from a (substituted) phenylhydrazine and an aldehyde or ketone under acidic conditions. [1] [2] The reaction was discovered in 1883 by Emil Fischer. Today antimigraine drugs of the triptan class are often synthesized by this method. The Fischer ...
[7] [8] Hydrazone-based coupling methods are used in medical biotechnology to couple drugs to targeted antibodies (see ADC), e.g. antibodies against a certain type of cancer cell. The hydrazone-based bond is stable at neutral pH (in the blood), but is rapidly destroyed in the acidic environment of lysosomes of the cell.
Phenylhydrazine was the first hydrazine derivative characterized, reported by Hermann Emil Fischer in 1875. [7] [8] He prepared it by reduction of a phenyl diazonium salt using sulfite salts. Fischer used phenylhydrazine to characterize sugars via formation of hydrazones known as osazones with the sugar aldehyde. He also demonstrated in this ...
Acetaldehyde is a common electrophile in organic synthesis. [31] In addition reactions acetaldehyde is prochiral. It is used primarily as a source of the "CH 3 C + H(OH)" synthon in aldol reactions and related condensation reactions. [32] Grignard reagents and organolithium compounds react with MeCHO to give hydroxyethyl derivatives. [33]
Separate storage of the aldehyde and base are necessary to prevent aldol polymerisation of the aldehyde. When exposed to an amine, reaction with acetaldehyde produces the enamine, which subsequently reacts with sodium nitroprusside to the imine. Finally, the iminium salt is hydrolysed to the bright blue [1] Simon-Awe complex. [3] [5]
Borsche–Drechsel cyclization is the central step in Borsche–Drechsel carbazole synthesis, where in the first step phenylhydrazine is condensed with cyclohexanone to form the cyclohexanone phenylhydrazone, and in the final step the resulting tetrahydrocarbazole is oxidized to carbazole itself.
The reaction uses NAD + to convert the ethanol into acetaldehyde (a toxic carcinogen). The enzyme acetaldehyde dehydrogenase (aldehyde dehydrogenase 2 family ALDH2, EC 1.2.1.3) then converts the acetaldehyde into the non-toxic acetate ion (commonly found in acetic acid or vinegar). [4] [6] This ion is in turn is broken down into carbon dioxide ...
This reaction is, overall, a condensation reaction as two molecules joining together with loss of water. Mechanistically, it is an example of addition-elimination reaction: nucleophilic addition of the -NH 2 group to the C=O carbonyl group, followed by the elimination of a H 2 O molecule: [3] X-ray structure of DNP-derived hydrazone of ...