Solvent-free condensations of ketones with malononitrile catalysed by methanesulfonic acid/morpholine system

Total Syntheses and Biological Evaluation of the Ganoderma lucidum Alkaloids Lucidimines B and C

“…Scheme 1 summarizes the preparation of lucidimines B ( 2 ) and C ( 3 ), which started with the condensation of commercially available cyclopentanone 5 with malononitrile under solvent-free conditions, 41 to give compound 7 (89%). Treatment of 7 with N , N -dimethylformamide dimethyl acetal (DMF-DMA) in the presence of a substoichiometric amount of acetic anhydride yielded the enamine 8 , which was then subjected to Pinner conditions 42 to provide the 2-bromonicotinonitrile 9 in 85% yield (over two steps).…”

“…The procedure for the preparation of 7 was adapted from the literature. 41 Thus, a magnetically stirred mixture of cyclopentanone ( 5 ) (10.0 g, 118.9 mmol), malononitrile ( 6 ) (9.4 g, 142.7 mmol), morpholine (0.5 g, 5.7 mmol), and methanesulfonic acid (0.5 g, 5.2 mmol) was heated at 120 °C for 1 h before being cooled to 18 °C. The mixture thus obtained was subjected to flash chromatography (silica, hexane elution) to afford, after concentration of the relevant fractions ( R f = 0.8), malononitrile 7 (14.0 g, 89%) as clear colorless oil.…”

Aqueous DABCO, an efficient medium for rapid organocatalyzed Knoevenagel condensation and the Gewald reaction

“…We next applied the conditions to the reactions of 1c-d with 2a-b. Due to the lower reactivities of these 2 ketones, their reactions were completed in slightly longer intervals giving 88%-92% of 3ca-db in 7-10 min (entries [5][6][7][8]. At the end of the reactions, most of the products precipitated spontaneously and could be separated by simple filtration.…”

“…In the framework of our studies on the chemistry of thiopyran-one structure 16 and its heterocyclic analogues, 17 and in continuation of our previous investigation on the development of aqueous mediated procedures, 18,19 we report herein the successful application of a H 2 O/1,4-diazabicyclo[2.2.2]octane (DABCO) * Correspondence: abaee@ccerci.ac.ir medium, which can cause rapid condensation of ketones 1 with malononitrile derivatives 2 to produce the Knoevenagel products 3 within a few minutes (3)(4)(5)(6)(7)(8)(9)(10). The products can be further converted to 2-aminothiophenes 4, either stepwise or in situ, to show the versatility of the method (Scheme).…”

Microwave-Assisted and Efficient Solvent-free Knoevenagel Condensation. A Sustainable Protocol Using Porous Calcium Hydroxyapatite as Catalyst

“…Nevertheless, most of these known methods suffer from significant limitations, which include toxic reagents, harsh reaction conditions, low yields or long reaction times. Only a few sustainable procedures and particularly with basic heterogeneous catalyst were reported [ 32 , 33 , 34 , 35 ].…”