86457-66-1Relevant articles and documents
Enantiopure isoplagiochin C by directed deracemization through axis-to-axis chirality transfer
Bringmann, Gerhard,Hager, Dominik,Schaumloeffel, Anu,Groh, Matthias,Speicher, Andreas
, p. 575 - 581 (2013/06/27)
Isoplagiochin C 1 was prepared for the first time in enantiopure form from synthetic racemic material, using a novel stereochemical concept. This macrocyclic bisbibenzyl contains two biaryl axes. Of these, axis A is configurationally stable by its fixation within the macrocyclic framework, while axis B is stereochemically unstable. By diesterification of rac-1 with enantiopure (P)-1,1′-binaphthyl-2,2′-dicarboxylic acid, axis B is locked in its P-configuration, thus allowing the resolution and separate saponification of dilactones (PA,PB,P)-3 and (M A,PB,P)-3 to give the pure enantiomers of 1. This concept permits recycling of any undesired enantiomer of 1 by thermal equilibration of the respective diastereomer of 3.
A designer axially chiral amino sulfonamide as an efficient organocatalyst for direct asymmetric anti/-selective mannich reactions and syw-selective cross-aldol reactions
Kano, Taichi,Yamaguchi, Yukako,Maruoka, Keiji
supporting information; experimental part, p. 6678 - 6687 (2010/02/28)
A direct asymmetric Mannich reaction using a novel axially chiral amino sulfonamide (S)-3 that is highly anti- and enantioselective has been developed. For instance, in the presence of a catalytic amount of (S)-3, the reactions between aldehydes and a-imino esters proceeded smoothly to give anti Mannich products with a significantly higher antilsyn ratio and enantioselectivity than previously possible. By utilizing N-Boc-protected aro-matic imines instead of a-imino esters, the synthetically useful Boc protecting group and various aromatic or heteroaromatic substituents were installed into the anti Mannich products and consequently the substrate scope of the anri'-selective Mannich reaction and the synthetic utility of the anti Mannich products have been expanded. The axially chiral amino sulfonamide (S)-3 has also been successfully applied to asymmetric direct cross-aldol reaction between two different aldehydes. The catalyst (S)-3 has the advantage of giving mainly syn products, whereas proline shows the opposite anti selectivity.
New, improved procedure for the synthesis of structurally diverse N-spiro C2-symmetric chiral quaternary ammonium bromides
Ooi, Takashi,Uematsu, Yukitaka,Maruoka, Keiji
, p. 4576 - 4578 (2007/10/03)
Selective, direct ortho magnesiation of (S)-2,2′bis(isopropoxycarbonyl)-1,1′-binaphthyl (6) has been achieved under mild conditions, using magnesium bis(2,2,6,6-tetramethylpiperamide) [Mg(TMP)2]. In combination with the subsequent reaction with