Methyl α-d-glucopyranoside based monoaza-15-crown-5 type lariat ethers with different heteroatom-containing side arm attached to the nitrogen of the macrocyclic ring have been synthesized. These compounds were used as chiral phase transfer catalysts in a few asymmetric reactions, such as Michael additions, Darzens condensation, and epoxidation of chalcone. The side arms of the macrocycles had a significant
Catalytic Asymmetric Conjugate Addition of Nitroalkanes to Cycloalkenones
作者:Stephen Hanessian、Vinh Pham
DOI:10.1021/ol000170g
日期:2000.9.1
Nitroalkanes add to cyclic and acyclic enones in an enantioselective manner in the presence of catalytic quantities of L-proline and trans-2,5-dimethylpiperazine as excess additive.
A convenient solvent-free synthesis of γ-nitroketones and γ-nitroesters based on the reaction of nitroalkanes with α,β-unsaturated carbonyl compounds in the ultrasonically activated heterogeneous catalytic system 1-butyl-3-methylimidazolium tetra-fluoroborate ([bmim][BF4])/K2CO3 has been developed. The system retained its catalytic activity over three reaction cycles.
In the presence of MS 4 Å in DMSO (dimethyl sulfoxide), Henry reaction with various carbonyl compounds and nitroalkanes proceeded smoothly to give the corresponding β-nitroalcohol without a base catalyst. Moreover, 1,4-additon of nitroalkane to α,β-unsaturated ketones was also performed in DMSO.
在 DMSO(二甲基亚砜)中加入 MS 4 Å 的情况下,各种羰基化合物与硝基烷烃的 Henry 反应顺利进行,无需碱催化剂即可得到相应的 β-硝基醇。此外,硝基烷烃对 α,β-不饱和酮的 1,4-加成反应也在 DMSO 中得以实现。
Synthesis and characterization of 4-aryl-5-(1-aryl-2-methyl-2-nitropropyl)-1,2,3-selenadiazoles
The synthesis of a new set of selenadiazoles, 4-aryl-5-(1-aryl-2-methyl-2-nitropropyl)-1,2,3-selenadiazoles (4) derived from 2-[4-methyl-4-nitro-1,3-diarylpentylidene]-1-hydrazinecarboxamide (3) has been reported. THF has been found to be the solvent of choice for this reaction. Structural features of 3 and 4 have been analyzed by NMR and X-ray techniques.