697286-99-0Relevant academic research and scientific papers
Lewis Acid Mediated [2,3]-Sigmatropic Rearrangement of Allylic α-Amino Amides
Blid, Jan,Brandt, Peter,Somfai, Peter
, p. 3043 - 3049 (2004)
Boron trifluoride and BBr3 mediated [2,3]-sigmatropic rearrangements of allylic α-amino amides have been developed affording secondary amines in good yields. (E)-Crotyl and (E)-cinnamyl α-amino amides 2b and 2c exhibit excellent syn-diastereoselectivity upon rearrangement with either Lewis acid. The allylic amine 2a forms upon treatment with BF 3 or BBr3 a five-membered heterocylic complex in which a single halide anion has been displaced by the carbonyl oxygen atom. The structures of the Lewis acid-amine complexes were elucidated using NMR spectroscopy. A plausible reaction mechanism, based on DFT calculations, is presented. Thus, BF3- or BBr3-complexed allylic amines 2 are shown to preferentially proceed, after deprotonation, via an endo transition state.
