The general rearrangement is depicted in Scheme I (1-2). If tautomer 3 is more stable than tautomer 2, conversion of 2 into 3 can occur either directly under the [2, 3]-sigmatropic rearrangement experimental conditions or in a subsequent step as we have already shown? However, at the best of our knowledge no X groups different from hydrogen have been used in the transformations 1-3. Such an overall process would imply a novel and important ...
