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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 .
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 ...
The Perkin reaction is an organic reaction developed by English chemist William Henry Perkin in 1868 that is used to make cinnamic acids.It gives an α,β-unsaturated aromatic acid or α-substituted β-aryl acrylic acid by the aldol condensation of an aromatic aldehyde and an acid anhydride, in the presence of an alkali salt of the acid.
Aside from acetic anhydride, trifluoroacetic anhydride and trifluoromethanesulfonic anhydride have been employed as activators. [4] Common nucleophiles besides acetates are arenes, alkenes, amides, and phenols. The usage of α-acyl sulfoxides and Lewis acids, such as TiCl 4 and SnCl 4, allow the reaction to proceed at lower temperatures (0 °C ...