111558-22-6Relevant articles and documents
Asymmetric Syntheses via Heterocyclic Intermediates, XXXVI.- Asymmetric Synthesis of Dimethyl (R)-4-Amino-4-methyl-2-pentenedioates (Dimethyl β,γ-Didehydro-α-methyl-D-glutamates) or Methyl (R)-2,5-Dihydro-2-methyl-5-oxo-2-pyrrolecarboxylates by the Bislactim Ether Method.- Studies ...
Schoellkopf, Ulrich,Schroeder, Juergen
, p. 87 - 92 (2007/10/02)
The lithiated bislactim ether 2a of cyclo(-L-Val-Ala-) reacts with the methyl acrylates 7-9 that carry a leaving group in β position, to give in an addition-elimination process the "Michael adducts" 10.The degree of the asymmetric inductions is exceptionally high (partly 99percent).On hydrolysis the compounds 10 furnish the (virtually enantiomerically pure) dimethyl (R)-β,γ-didehydro-α-methylglutamates 13 or methyl (R)-2,5-dihydro-2-methyl-5-oxo-2-pyrrole carboxylates 15. - The lithiated bislactim ether 2b of cyclo(-L-Val-Glu-) reacts with the acrylates 7-9 analogously to give initially the "Michael adducts" 11.However, these isomerize readily to yield the compounds 16, the precursors of dimethyl α,β-didehydroglutamates of type 17.
