Amino-Claisen Rearrangment of N-Allyl Aryl Amines: A Versatile Precursor in the Palladium Catalyzed Hetroannultation to IndolesAuthor(s): Pratima Sharma, Navjeet Kaur, Seema Jain and Dharma Kishore
The [3,3]-sigmatropic shift of vinyl and aryl allyl ether is known as claisen rearrangement. It has been extensively studied and exploited as an expeditious approach to carbon-carbon bond formation in organic synthesis1-3. Similarly, the nitrogen4 analogues of Claisen rearrangement are of importance in view of synthetic and mechanistic aspects. The nitrogen analogue of the simple Claisen rearrangement with N-allylaniline and related derivatives is called the amino-Claisen rearrangement (or aza-Claisen rearrangement)5. (It is the [3,3]-sigmatropic shift of N- alkenyl-N-arylamine to furnish 2-alkenylarylamine, which is known as the amino-Claisen rearrangement). Anilines substituted at 2-position are valuable materials for the construction of a number of different classes of compounds. In particular, 2-alkenylanilines are converted to indoles by means of a palladium-catalyzed cyclization process6. They also serve as precursors for the preparation of quinolines and cinnolines7.