An improved large scale synthesis of the Schoellkopf chiral auxiliaries: (2R)-and (2S)-2,5-Dihydro-3,6-dimethoxy-2-isopropylpyrazine

Article abstract of DOI:10.1021/op049777t

Syntheses of the Schoellkopf chiral auxiliaries have been carried out on large scale in high overall yields from D- and L-valine. This method avoids the use of highly toxic phosgene or triphosgene, low-temperature reactions, and unstable intermediates.