alpha-Alkyl beta-amino esters are available in high diastereoselectivity through a silicon-free Claisen enolate [3,3]-sigmatropic rearrangement of enamide esters. Optimisation studies have probed the crucial role of the initial enolisation and the nature of the enamide N-centre. The demonstration of chirality transfer and the formation of beta-proline systems, is also presented.
Harker, W. R. R., Carswell, E. L., & Carbery, D. R. (2012). Si-free enolate Claisen rearrangements of enamido substrates. Organic and Biomolecular Chemistry, 10(7), 1406-1410. https://doi.org/10.1039/c2ob06853b