Dehydration Reaction of Hydroxamic Acids with Unsaturated Ethers

Dehydration reactions of hydroxamic acids with unsaturated ethers have been studied. The reaction of hydroxamic acids with ethoxyacetylene or methylketene diethylacetal led to the formation of corresponding isocyanates, along with ethyl acetate or ethyl propionate and ethanol, through the intermediate of addition compounds of hydroxamic acids and the dehydrating reagents. The reaction of hydroxamic acids with n-butyl vinyl ether, on the other hand, led to the formation of dihydroxamic acids, along with acetaldoxime and acetaldehyde dibutyl-acetal. This type of reaction was further extended to the reactions of hydroxamic acids with propenyl ether, acetals and aldehydes, and the formation of dihydroxamic acids was confirmed.