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For example, β-aryl carboxylic acids can be efficiently converted to β-aryl ketones by treatment of an acetic anhydride solution of the acid with catalytic N-methylimidazole. This reactivity is attributed in part to generation of acetylimidazolium, a powerful cationic acetylating agent, in situ. [11] Modified Dakin-West reaction
The Boekelheide reaction is a rearrangement of α-picoline-N-oxides to hydroxymethylpyridines. It is named after Virgil Boekelheide who first reported it in 1954. [ 1 ] Originally the reaction was carried out using acetic anhydride , which typically required a period at reflux (~140 °C).
Acetic anhydride, or ethanoic anhydride, is the chemical compound with the formula (CH 3 CO) 2 O. Commonly abbreviated Ac 2 O , it is the simplest isolable anhydride of a carboxylic acid and is widely used as a reagent in organic synthesis .
2-Pyrone can be obtained by a cyclisation reaction, and converted to 2-pyridone via an exchange reaction with ammonia: Pyridine forms an N-oxide with some oxidation agents such as hydrogen peroxide. This pyridine-N-oxide undergoes a rearrangement reaction to 2-pyridone in acetic anhydride: [21] [22] [23]
Hippuric acid, the benzamide derivative of glycine, cyclizes in the presence of acetic anhydride, condensing to give 2-phenyl-oxazolone. [3] This intermediate also has two acidic protons and reacts with benzaldehyde, acetic anhydride and sodium acetate to a so-called azlactone. This compound on reduction gives access to phenylalanine. [4]
The following figure shows the reaction mechanism: [2] Reaktionsmechanismus Albright-Goldman-Oxidation. First, dimethyl sulfoxide (1) reacts with acetic anhydride to form a sulfonium ion. It reacts with the primary alcohol in an addition reaction. Furthermore, acetic acid is cleaved, so that intermediate 2 is formed. The latter reacts upon ...
The reaction conditions allow oxidation of acid-sensitive compounds, which might decompose under the acidic oxidation conditions such as Jones oxidation. For example, in Thompson & Heathcock's synthesis of the sesquiterpene isovelleral, [ 15 ] the final step uses the Swern protocol, avoiding rearrangement of the acid-sensitive ...
A common type of organic acid anhydride is a carboxylic anhydride, where the parent acid is a carboxylic acid, the formula of the anhydride being (RC(O)) 2 O. Symmetrical acid anhydrides of this type are named by replacing the word acid in the name of the parent carboxylic acid by the word anhydride. [2] Thus, (CH 3 CO) 2 O is called acetic ...