Synthesis and Reactions of α‐Bromo‐N‐alkoxyimidates

The reaction of alkyl hydroxamates 2 with (C₂H₅)₃O · BF₄ in CH₂Cl₂ affords N‐alkoxyimidates 3. The direct alkylation of hydroxamic acids 1 with 1,2‐dibromoethane gives the 5,6‐dihydro‐1,4,2‐dioxazine derivatives 4. The reactions of the acyclic imidates 3 as well as the cyclic N‐alkoxyimidates 4 with N‐bromosuccinimide in CCl₄ produces the α‐bromoimidates 5a–d and 6a–d. The α‐bromine atom in the bromides 5b, d and 6a, b, d can be displaced by fluorine and azido substituents to yield the α‐fluoro‐N‐alkoxyimidates 7b, d and 10a, b, d and the α‐azido compounds 8b, d and 11a, b, d, respectively. The reduction of the azides 8b, d and 11a, b, d affords the α‐aminoimidates 9b, d and 12a b, d, respectively. The reaction of the bromides 6a–d with benzene derivatives 14a–d in the presence of AgBF₄ affords the aromatic substitution products 15a–d. Acid‐catalyzed hydrolysis of 15a, c gives the arylsubstituted carboxylic acids 16 and 17.