In organic chemistry, the Cornforth rearrangement is a rearrangement reaction of a 4-acyloxazole in which the group attached to an acyl on position 4 and the substituent on position 5 of an oxazole ring exchange places. It was first reported in 1949, and is named for John Cornforth. The reaction is used in the synthesis of amino acids, where the corresponding oxazoles occur as intermediates.