title: Asymmetric aza-[2,3]-Wittig sigmatropic rearrangements: chiral auxiliary control and formal asymmetric synthesis of (2S, 3R, 4R)-4-hydroxy-3-methylproline and (-)-kainic acid.
abstract: A survey of 16 different chiral auxiliaries and a variety of strategies found that an (-)-8-phenylmenthol ester of a glycine derived migrating group can control the absolute stereochemistry of aza-[2,3]-Wittig sigmatropic rearrangements with diastereoselectivities of ca. 3 : 1 with respect to the auxiliary. In two specific examples, ca. 50% yields of enantiomerically pure products were obtained after chromatographic purification. These were synthetically manipulated with no erosion of stereochemistry into intermediates that completed formal asymmetric syntheses of (+)-HyMePro and (-)-kainic acid.
authors: School of Chemistry, University of Nottingham, Nottingham, UK NG7 2RD. j.anderson@nottingham.ac.uk
authors: James C
authors: JC
authors: Anderson
authors: Julian M A
authors: JM
authors: O'Loughlin
authors: James A
authors: JA
authors: Tornos
mesh_terms: D007608:Kainic Acid / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D011392:Proline / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization; D016339:Spectrometry, Mass, Fast Atom Bombardment; D013237:Stereoisomerism
chemical_list: C511300:(2S, 3R, 4R)-4-hydroxy-3-methylproline; D011392:Proline; D007608:Kainic Acid