Acylhydroxamic acid derivatives

A formal synthesis of ( )-Eseroline (69) via a 3-aza-4-oxa-Cope rearrangement was reported. An iV-aryl A-hydroxycarbamate was reacted with 2-phenylsulfanylpropanoic acid to yield the O-acylhydroxamic acid derivative 65, R = H that rearranged in the presence of potassium bis(trimethylsilyl)amide. The [3,3] and [3,5] rearrangement products, respectively 66 and 67, were formed (equation 22). If the para-substituted hydroxamic acid 65, R = OCOBu-t is used, no [3,5] rearrangement product is observed and the [3,3] rearrangement product 68 is the only product formed (equation 23). The authors proposed two parallel mechanisms, a concerted pathway and an ionic mechanism by an ion-pair recombination. 

Activated A-alkyl-O-acylhydroxamic acid derivatives 75 undergo base catalysed rearrangement to give 2-acyloxyamides 76 in good to excellent yields (50-100%) (equation 26). These precursors of 2-hydroxy amides (77) are good intermediates to prepare ethanol-amines, oxindoles and oxazolidinediones. 

Aimnoethyl)indoles have been prepared from 3-hydroxy-2-methoxyindolines by way of a Claisen o-amide rearrangement. 0-Acylhydroxamic acid derivatives (82) have been found to undergo a base-catalysed rearrangement to give secondary... 

In an early study on the mechanism of the Beckmann rearrangement, Jones and Hurd showed that the silver salts of JV-acylhydroxamic acids 16 decomposed upon heating in the solid state to produce the corresponding isocyanates 1734. The silver derivative of propane-l,2-diol-3-thiol ( thiovanol ) 18 undergoes thermal decomposition to deposit... 

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