Named rearrangements Curtius

Into this group fall the named oxidation rearrangement reactions which proceed with carbon-carbon bond cleavage and 1,2-transfer of an alkyl group to a heteroatom, such as the Baeyer-Villiger reaction (discussed in Chapter 5.1, this volume) and the Beckmann reaction (found in Chapter 5.2, this volume) of ketones, as well as the Hofmann reaction/Schmidt reaction/Curtius reanangement of carboxylic acid derivatives. The two examples discussed here involve related reactions of alcohols. 

The rearrangement has a mechanism similar to those of the Hofmann rearrangement of amides, the Lossen rearrangement of acylhydroxamic esters, the Schmidt rearrangement of carbonyl compounds and the Wolff rearrangement of diazoketones. Evidence concerning the mechanism of one can often be applied to the others, and the whole family has been reviewed briefly . Sometimes the distinction is made that the conversion of an acyl azide into an isocyanate or urethane is the Curtius rearrangement whereas the overall sequence is the Curtius reaction, but usually the former name is used for both processes. 

Degradation reactions of carboxylic acids and their derivatives to amines and their derivatives with one less carbon unit involve rearrangements of a carbon to an electron deficient nitrogen atom as key steps, namely the Hofmann Curtius (C), - Schmidt and Lessen rearrangements, as... 

In 1899, Erdmann obtained the same compound in good yield from anthranilic acid and phosgene and suggested the name isatoic anhydride. An alternative synthesis of isatoic anhydride [2//-3,l-benzoxazine-2,4(lH)-dione, subsequently abbreviated as lA] was found by Curtius and Semper from phthalic acid monoazide (5) via o-carboxyphenyl isocyanate. Similar rearrangements were discovered by Bredt and Hor [from potassium phthal-imide (6)] and by Mohr [from phthalimide (7)] leading to IA via a Hoffmann reaction. 

In this section we have explored a number of rearrangement reactions that involve ketenes or ketene-like intermediates. Notice that each of these rearrangements is a name reaction (Wolff, Arndt-Eistert, Hofmann, and Curtius). Don t panic about keeping the specifics of the reactions connected to the names. Most instructors will not ask you to reproduce the reactions by name. However, if your future includes organic chemistry, you wiU see them again and become familiar with them. Of course if your future does not include organic chemistry, at least you can appreciate the predictability and trends these reactions illustrate. 

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