Size-dependent catalysis by DABCO-functionalized Zn-MOF with one-dimensional channels
作者:Ja-Min Gu、Wan-Seok Kim、Seong Huh
DOI:10.1039/c1dt11274k
日期:——
Lewis basic DABCO-functionalized 3D-like metal–organic framework, Zn-MOF, catalyzesnitroaldol (Henry) reaction of 4-nitrobenzaldehyde with nitroalkanes in a size-dependent manner. Small nitroalkanes give rise to higher conversion than larger ones. This MOF-based heterogeneouscatalyst is very robust and can be recycled several times without losing its activity.
DMSO and in water in the presence of tetrabutylammonium bromide (TBAB) as a phase transfer catalyst. Negligible background reactions (i.e., negative control experiment in the absence of keratin protein) were observed in these solvent systems. Aromatic aldehydes bearing electron-donating groups and aliphatic aldehydes showed poor or no conversion, respectively. In general, the reactions in water/TBAB
A Highly<i>anti</i>-Selective Asymmetric Henry Reaction Catalyzed by a Chiral Copper Complex: Applications to the Syntheses of (+)-Spisulosine and a Pyrroloisoquinoline Derivative
作者:Kun Xu、Guoyin Lai、Zhenggen Zha、Susu Pan、Huanwen Chen、Zhiyong Wang
DOI:10.1002/chem.201201775
日期:2012.9.24
A highly anti‐selective asymmetricHenryreaction has been developed, affording synthetically versatile β‐nitroalcohols in a predominately anti‐selective manner (mostly above 15:1) and excellent ee values (mostly above 95 %). Moreover, the anti‐selective Henryreaction was carried out in the presence of water for the first time with up to 99 % ee. The catalytic mechanism was proposed based on the detection
Clean five-step synthesis of an array of 1,2,3,4-tetra-substituted pyrroles using polymer-supported reagents
作者:Marina Caldarelli、Jörg Habermann、Steven V. Ley
DOI:10.1039/a809345h
日期:——
Polymer-supported reagents and other solid sequestering agents may be used to generate an array of 1,2,3,4-tetra-substituted pyrrole derivatives without any chromato-graphic purification step.
preparation in THF, a heterogeneous mixture developed and centrifugation of the suspension allowed for separation of the precipitate, which contained the active catalyst and which could be stored for at least 1 month without any loss of catalytic performance. The precipitate promoted a nitroaldol (Henry) reaction for a broad range of nitroalkanes and aldehydes under heterogeneous conditions, affording
描述了由 Nd(5)O(O(i)Pr)(13)、基于酰胺的配体和 NaHMDS(六甲基二硅肼钠)组成的异双金属催化剂促进的抗选择性催化不对称硝基醛醇反应的全部细节。酰胺基配体的系统合成和评估导致最佳配体1m的鉴定,这为Nd/Na异质双金属配合物提供了合适的平台。在 THF 中制备催化剂的过程中,形成了一种非均相混合物,悬浮液的离心允许沉淀物分离,其中含有活性催化剂并且可以储存至少 1 个月而不会损失任何催化性能。沉淀促进了多种硝基烷烃和醛在非均相条件下的硝基醛醇 (Henry) 反应,得到相应的 1, 2-硝基烷醇以高度抗选择性(高达 anti/syn = >40/1)和对映选择性方式(高达 98% ee)。电感耦合等离子体 (ICP) 和 X 射线荧光 (XRF) 分析表明,沉淀确实包含钕和钠,高分辨率 ESI TOF MS 光谱法进一步支持了这一点。