1309465-22-2Relevant academic research and scientific papers
Stereodivergent direct catalytic asymmetric mannich-type reactions of α-isothiocyanato ester with ketimines
Lu, Gang,Yoshino, Tatsuhiko,Morimoto, Hiroyuki,Matsunaga, Shigeki,Shibasaki, Masakatsu
supporting information; experimental part, p. 4382 - 4385 (2011/06/24)
Now accessible: Sterically hindered vicinal tetrasubstituted carbon stereocenters, which are not accessible by asymmetric hydrogenation, were constructed by a catalytic asymmetric C-C bond formation (see scheme; Dpp=diphenylphosphinoyl). By changing the Group 2 metal center, stereodivergent access to α,β-tetrasubstituted α,β-diamino esters was realized. Copyright
Construction of contiguous tetrasubstituted chiral carbon stereocenters via direct catalytic asymmetric aldol and mannich-type reactions
Matsunaga, Shigeki,Yoshino, Tatsuhiko
scheme or table, p. 260 - 268 (2012/07/14)
Catalytic asymmetric synthesis of unnatural amino acids with vicinal tetrasubstituted chiral carbon stereocenters is described. In the first part, direct catalytic asymmetric aldol reaction of simple non-activated ketone electrophiles with α-substituted α-isothiocyanato ester donors was realized. A Mg/Schiff base catalyst promoted the aldol reaction, and α-amino-β-hydroxy esters were obtained in up to 98% ee and 98:2 d.r. In the second part, the Mg/Schiff base catalyst and a Sr/Schiff base catalyst were utilized for stereodivergent direct asymmetric Mannich-type reaction of ketimines. The Mg/Schiff base catalyst gave syn-α,β-diamino esters, while the Sr/Schiff base catalyst produced anti-α,β-diamino esters in good to high enantioselectivity, up to 97% ee.
