Zinc metal–organic frameworks: efficient catalysts for the diastereoselective Henry reaction and transesterification
作者:Anirban Karmakar、M. Fátima C. Guedes da Silva、Armando J. L. Pombeiro
DOI:10.1039/c4dt00219a
日期:——
Three new amidoterephthalate ligands are utilized to synthesize three new zinc(ii) metal–organic frameworks which act as heterogeneous catalysts for the diastereoselective nitroaldol (Henry) and transesterification reactions.
New Highly Asymmetric Henry Reaction Catalyzed by CuII and aC1-Symmetric Aminopyridine Ligand, and Its Application to the Synthesis of Miconazole
作者:Gonzalo Blay、Luis R. Domingo、Victor Hernández-Olmos、José R. Pedro
DOI:10.1002/chem.200800069
日期:2008.5.19
A new catalytic asymmetricHenryreaction has been developed that uses a C(1)-symmetric chiral aminopyridineligand derived from camphor and picolylamine. A variety of aromatic, heteroaromatic, aliphatic, and unsaturated aldehydes react with nitromethane and other nitroalkanes in the presence of DIPEA (1.0 equiv), Cu(OAc)(2)*H(2)O (5 mol %), and an aminopyridineligand (5 mol %) to give the expected
Synthesis of chiral salalen ligands and their in-situ generated Cu-complexes for asymmetric Henry reaction
作者:Ashish Dixit、Pramod Kumar、Surendra Singh
DOI:10.1002/chir.23019
日期:2018.12
Chiral salalen ligands derivedfrom (S)‐proline and derivatives of salicyaldehydes were synthesized, and their in‐situ generated Cu (II) complexes were evaluated in the asymmetric Henry reaction. Salalen ligand of different substituents on the phenyl moiety showed remarkable effect on the enantioselectivity of nitro‐aldol product of 4‐nitrobenzaldehyde and nitromethane. Cu (II) complex generated in
合成了衍生自(S)-脯氨酸和水杨醛衍生物的手性Salalen配体,并在不对称Henry反应中评估了它们原位生成的Cu(II)配合物。苯基部分上不同取代基的Salalen配体对4-硝基苯甲醛和硝基甲烷的硝基羟醛产物的对映选择性表现出显着影响。与(S)-2-(叔丁基)-6(((2-((((2-羟基-3-甲基苄基)氨基)甲基)吡咯烷烃-1-基)甲基)生成的Cu(II)络合物苯酚(10 mol%)和Cu(OAc)2 .H 2O(10 mol%)被发现是4-硝基苯甲醛与硝基甲烷之间硝基-羟醛反应的较好催化剂,40小时后,在35°C下,异丙醇中的相应产物收率为85%,对映体过量(ee)为88%。还以不同的取代的苯甲醛用于亨利反应的催化剂和相应的产物以22%至99%的产率和66%至92%的ee获得。4-硝基苯甲醛与前手性硝基乙烷的亨利反应产生抗选择性产物(dr = 79/21; anti / syn),收率为91%,ee为80%。
Copper Complex of Aminoisoborneol Schiff Base Cu
<sub>2</sub>
(SBAIB‐d)
<sub>2</sub>
: An Efficient Catalyst for Direct Catalytic Asymmetric Nitroaldol (Henry) Reaction
new bifunctional coppercomplex of the aminoisoborneolSchiffbase – Cu2(SBAIB‐d)2 – has been developed for the effective directcatalyticasymmetricHenryreaction. One mol% of this catalyst produces the expected Henry products in high yields (up to 99%) with excellent enantioselectivities (up to 98% ee). The utility of the present catalyst was also extended to the Henryreaction with nitroethane
The effectiveness of neutral pH chitosan hydrogel beads (CSHB) as a green organocatalyst for a variety of CâC bond forming reactions (i.e. aldol reaction, Knoevenagel condensation, nitroaldol (Henry) reaction, Michael addition) has been comprehensively evaluated. Reaction rates, conversions and selectivities were studied as a function of a series of input variables including size, pH and reactive surface area of the beads, catalyst loading, temperature, molecular weight of the biopolymer, concentration, solvent system and molar ratio of reactants. Moreover, the catalytic biohydrogel beads were characterized by a variety of techniques including, among others, SEM, FT-IR, TGA and DSC.