528838-69-9Relevant academic research and scientific papers
Non-C2-symmetric, chirally economical, and readily tunable linked-binols: Design and application in a direct catalytic asymmetric mannich-type reaction
Yoshida, Takamasa,Morimoto, Hiroyuki,Kumagai, Naoya,Matsunaga, Shigeki,Shibasaki, Masakatsu
, p. 3470 - 3474 (2005)
(Chemical Equation Presented) An achiral unit is shown to be better than a chiral unit in promoting an asymmetric reaction. Non-C2-symmetric linked-binols 1 with one chiral 1,1′-bi-2-naphthol unit and one flexible achiral unit are employed as l
Direct catalytic asymmetric Mannich-type reaction of hydroxyketone using a Et2Zn/linked-BINOL complex: Synthesis of either anti- or syn-β-amino alcohols
Matsunaga, Shigeki,Yoshida, Takamasa,Morimoto, Hiroyuki,Kumagai, Naoya,Shibasaki, Masakatsu
, p. 8777 - 8785 (2007/10/03)
Full details of a direct catalytic asymmetric Mannich-type reaction of a hydroxyketone using a Et2Zn/(S,S)-linked-BINOL complex are described. By choosing the proper protective groups on imine nitrogen, either anti- or syn-β-amino alcohol was obtained in good diastereomeric ratio, yield, and excellent enantiomeric excess using the same zinc catalysis. N-Diphenylphosphinoyl (Dpp) imine 3 gave anti-β-amino alcohols in anti/syn = up to >98/2, up to >99% yield, and up to >99.5% ee, while Boc-imine 4 gave syn-β-amino alcohols in anti/syn = up to 5/95, up to >99% yield, and up to >99.5% ee. The high catalyst turnover number (TON) is also noteworthy. Catalyst loading was successfully reduced to 0.02 mol % (TON = up to 4920) for the anti-selective reaction and 0.05 mol % (TON = up to 1760) for the syn-selective reaction. The Et2Zn/(S,S)-linked-BINOL complex exhibited far better TON than in previous reports of catalytic asymmetric Mannich-type reactions. Mechanistic studies to clarify the reason for the high catalyst efficiency as well as transformations of Mannich adducts are also described.
Anti-selective direct catalytic asymmetric Mannich-type reaction of hydroxyketone providing β-amino alcohols
Matsunaga, Shigeki,Kumagai, Naoya,Harada, Shinji,Shibasaki, Masakatsu
, p. 4712 - 4713 (2007/10/03)
An anti-selective direct catalytic asymmetric Mannich-type reaction is described. The Et2Zn/(S,S)-linked-BINOL 1 = 4/1 complex promoted a Mannich-type reaction of 2-hydroxy-2′-methoxyacetophenone (2) and N-diphenylphosphinoyl imines 3. Using as
