93684-65-2Relevant academic research and scientific papers
Diastereoselective Construction of α-Quaternary Carbon Centers in the Chiral-Auxiliary-Mediated Aza-Claisen Rearrangement of Ketene N-Allyl-N,O-acetals
Kurth, Mark J.,Brown, Edward G.
, p. 362 - 366 (2007/10/02)
The aza-Claisen rearrangement of ketene N-allyl-N,O-acetals has been applied to the diastereoselective construction of precursors of 2-quaternary 4-pentenoic acids (82-97percent ds).Best yields are obtained when alkoxides are used to deprotonate the intermediate oxazolinium salts.
Asymmetric Induction in the Claisen Rearrangement of N-Allylketene N,O-Acetals
Kurth, Mark J.,Decker, Owen H. W.,Hope, Hakon,Yanuck, Michael D.
, p. 443 - 448 (2007/10/02)
Asymmetric C-C bond formation via the diastereoselective aza-Claisen rearrangement of N-allylketene N,O-acetal 1 is described.Diastereoselection noted for rearrangement 1->2 ranges from 84percent to 96percent and is a consequence of complete (Z)-N,O-acetal olefin selectivity in 1, high Cα-si-face selectivity in the rearrangement of 1 to 2, and the absence of Cα epimerization in oxazoline 2.Experiments which establish the steric bulk of the C4 appendage as a particularly important variable are also reported.Acid-catalyzed hydrolysis of rearranged oxazoline 2 completes an efficient, enantioselective synthesis of 2-substituted pent-4-enoic acid 4 and regenerates for recycling the chiral auxiliary reagent 3, initially prepared from inexpensive α-amino acids.
