1219808-79-3Relevant academic research and scientific papers
Heterobimetallic transition metal/rare earth metal bifunctional catalysis: A Cu/Sm/schiff base complex for Syn -selective catalytic asymmetric nitro-mannich reaction
Handa, Shinya,Gnanadesikan, Vijay,Matsunaga, Shigeki,Shibasaki, Masakatsu
supporting information; experimental part, p. 4925 - 4934 (2010/06/18)
The full details of a catalytic asymmetric syn-selective nitro-Mannich reaction promoted by heterobimetallic Cu/Sm/dinucleating Schiff base complexes are described, demonstrating the effectiveness of the heterobimetallic transition metal/rare earth metal bifunctional catalysis. The first-generation system prepared from Cu(OAc)2/Sm(O-iPr)3/Schiff base 1a = 1:1:1 with an achiral phenol additive was partially successful for achieving the syn-selective catalytic asymmetric nitro-Mannich reaction. The substrate scope and limitations of the first-generation system remained problematic. After mechanistic studies on the catalyst prepared from Sm(O-iPr)3, we reoptimized the catalyst preparation method, and a catalyst derived from Sm 5O(O-iPr)13 showed broader substrate generality as well as higher reactivity and stereoselectivity compared to Sm(O-iPr)3. The optimal system with Sm5O(O-iPr)13 was applicable to various aromatic, heteroaromatic, and isomerizable aliphatic N-Boc imines, giving products in 66-99% ee and syn/anti = >20:1-13:1. Catalytic asymmetric synthesis of nemonapride is also demonstrated using the catalyst derived from Sm5O(O-iPr)13.
Bifunctional-thiourea-catalyzed diastereo- And enantioselective Aza-Henry reaction
Xu, Xuenong,Furukawa, Tomihiro,Okino, Tomotaka,Miyabe, Hideto,Takemoto, Yoshiji
, p. 466 - 476 (2008/09/20)
Bifunctional thiourea 1a catalyzes aza-Henry reaction of nitroalkanes with N-Boc-imines to give syn-β-nitroamines with good to high diastereo- and enantioselectivity. Apart from the catalyst, the reaction requires no additional reagents such as a Lewis acid or a Lewis base. The N-protecting groups of the imines have a determining effect on the chirality of the prod ucts, that is, the reaction of N-Bocimines gives R adducts as major products, whereas the same reaction of N-phosphonoylimines furnishes the corresponding S adducts. Various types of nitroalkanes bearing aryl, alcohol, ether, and ester groups can be used as nucleophiles, providing access to a wide range of useful chiral building blocks in good yield and high enantiomeric excess. Synthetic versatility of the addition products is demonstrated by the transformation to chiral piperidine derivatives such as CP-99,994.
