Double chiral induction in ul-selective Michael additions of metal enolates of N-bornylideneglycinates to (E)-4,5-dioxy-2-pentenoates. Exclusive ul,lk-1,2-chiral induction leading to l,u-Michael adducts

1-[(4-Methylphenyl)sulfonyl]pyrrolidin-2-one

“…The molecular dimensions in (I) are in agreement with the corresponding distances reported for a few structures containing a phenylsulfonylpyrrolidin-2-one fragment in the Cambridge Structural Database (Version 5.27;Allen, 2002), e.g. refcodes GUBNOG (Iwamatsu et al, 1999), JIRKOK and JIRLAX (Amato et al, 1990), KONJAY (Bandoli et al, 1992), QACQUH (Benerjee et al, 2002), QELJUM (Clark et al, 1999), SOVDOW and SOVDUC (Amato et al, 1991), and WEPDOK (Taksukawa et al, 1993).…”

Stereoselective Michael Addition of Glycine Anions to Chiral Fischer Alkenylcarbene Complexes. Asymmetric Synthesis of β-Substituted Glutamic Acids

“…The anti relative configuration assigned to oxidation products 9 was confirmed in two cases by conversion of imino esters 9a , f , used as diastereomerically pure major (anti) isomers, to cyclic lactams rac - 12a and 12a as detailed in Scheme . Cleavage of the imine was performed with hydroxylamine hydrochloride and sodium acetate in ethanol at reflux 6c. Under these conditions racemic compound 9a led to a mixture of 11a and its cyclized product rac - 12a that were readily separated by column chromatography.…”

“…Thus, the most classical ones include Schöllkopf bislactim ethers, 5,6-disubstituted N -acyl oxazinones, 2-( tert -butyl)-3-methyl-4-imidazolidinone, or Oppolzer's camphor sultam . An alternative asymmetric derivatization of glycine esters is the formation of Schiff's bases with chiral ketones such as camphor or 2-hydroxypinan-3-one, or the formation of a nickel(II) complex of a Schiff base of glycine derived from a chiral ketone like ( S )- o -[ N -( N -benzylprolyl)amino]benzophenone . In all these approaches the source of chirality, to generate the α-amino acid stereogenic center, is always present on the glycinate anion synthon.…”

“…The preparation of enantiomerically pure glutamic acid derivatives, by a Michael addition reaction, can be achieved by two possible disconnection pathways of the C 2 −C 3 bond as shown in Scheme . While pathway A has been widely explored using the chiral aforementioned glycine synthons, − disconnection pathway B, where the source of chirality resides on the Michael acceptor, has been much less investigated. To our knowledge only three isolated examples of synthetic approach B have been reported, in which ethyl ( E )-3-[( S )-2,2-dimethyl-1,3-dioxolan-4-yl]propenoate, (4 S )-3-[( E )-4‘-bromo-4,4‘-difluoro-2‘-butenoyl]-4-alkyl-2-oxazolidinone (alkyl = benzyl, isopropyl), and ( R )-4-methylene-2-phenyloxazolidin-5-one or the corresponding ( S )-2- tert -butyl derivative 16 are employed as chiral Michael acceptors…”

Double Chiral Induction Enables a Stereoselective Carbonyl Allylation with Simple Alkenes under the Sequential Catalysis of Palladium Complex and Chiral Phosphoric Acid

“…Interestingly, the use of CPA4 to replace CPA1 resulted in a moderate yield, but with 81% ee under otherwise identical reaction conditions (entry 3). Double chiral induction has been considered to be a powerful strategy for the development of stereoselective reactions . Thus, bis­(pinane­diolato)­diboron 2b , , a commercially available chiral reagent, was tested and found to give product 4a in 49% yield and with 91% ee (entry 4).…”