The oxidative rearrangement of O,O′-diacylderivatives of leucoindigo with dichlorodicyanobenzoquinone in dimethyl sulphoxide affords N,N′-diacylderivatives of indigotin in high yield; it has been found that the heat of cis-to-transisomerization in acetonitrile for N,N′-bis (phenylacetyl) indigotin is 29.9 kcal mol–1(60 cal g–1).