Knoevenagel Condensation Catalysed by New Montmorillonitesilylpropylethylenediamine

Arylidenemalononitriles as Versatile Synthons in Heterocyclic Synthesis

BACKGROUND

Arylidenemalononitriles are valuable synthons for the construction of a variety of novel complex heterocyclic motifs, fused heterocycle derivatives and spirocyclic compounds. They are versatile chemical intermediates and have increasing applications in industry, agriculture, medicine, biological science.

OBJECTIVE

The aim of this review is to highlight the preparation methods and reactions of arylidenemalononitriles in the synthesis of various heterocyclic compounds.

CONCLUSION

In this review, we have presented the application of arylidenemalononitriles to construct a variety of heterocycles. Various catalysts for the preparation of arylidnemalononitriles have been described.

Functionalized microporous organic nanotube networks as a new platform for highly efficient heterogeneous catalysis

A novel amino-functionalized microporous organic nanotube networks (NH₂-MONNs) as heterogeneous base catalyst was successfully synthesized by combination of hyper-cross-linking and molecular templating of multicomponent bottlebrush copolymers.

An easy-to-use heterogeneous catalyst for the Knoevenagel condensation

Physical mixtures of alkali and earth alkali metal carbonates and commercially available zeolites were investigated as solid catalysts for the Knoevenagel condensation. Best results for the model reaction between benzaldehyde and ethyl cyanoacetate were obtained for a 1:4 mixture of Na2CO3 with 4 Å molecular sieves (MS). The effects of the following parameters were investigated: structure of substrate, type and basicity of metal carbonate and zeolite, and temperature. Between 50 and 90°C chemical yields up to >90% were obtained without continuous removal of water and with reasonable catalyst activities and reaction times. Na2CO3 – MS 4 Å proved to be active for the condensation of several aldehydes and ketones with a variety of active methylene components.Key words: Knoevenagel condensation, solid basic catalysts, zeolite – sodium carbonate mixtures.