Efficient three-component Gewald reactions under Et<sub>3</sub>N/H<sub>2</sub>O conditions
作者:M. Saeed Abaee、Somayeh Cheraghi
DOI:10.1080/17415993.2013.860141
日期:2014.5.4
In a medium consisting of triethylamine and water, alpha-methylene ketones undergo room temperature Gewald reactions with elemental sulfur and ethyl cyanoacetate (or malononitrile) to yield 2-aminothiophene derivatives efficiently within short time periods. Because of the high polarity of the medium, products precipitate in the reaction mixtures spontaneously. This makes isolation of the products easy by simple filtration and avoids cumbersome chromatographic separations. Mechanistic studies suggest that the reactions proceed via a Knoevenagel condensation pathway.
New hetero-annelation reactions using N-[bis-(methylthio)-methylene]-amino and related reagents
作者:F. Sauter、J. Fr�hlich、E. K. Ahmed
DOI:10.1007/bf00813798
日期:1996.3
Reaction of acyclic (R(1-3)) and cyclic (R(4-5)) BMMA (=N-[bis-(methylthio)-methylene]-amino) reagents with Gewald-type thiophene derivatives (2, 3) led to annelation of pyrimidine moieties. Thus, linear thiazolo- or thiazino- and pyrrolo-, pyrido- or azepino-fused thiopyrano[4',3':4,5]thieno-[2,3-d]pyrimidines (5 and 6) as well as the angular imidazo-fused thiopyrano[4,'3':4,5]thieno-[2,3-d]pyrimidine 8 were easily obtained from one-pot reactions in good yields.
Elslager,E.F. et al., Journal of Heterocyclic Chemistry, 1972, vol. 9, p. 775 - 782
作者:Elslager,E.F. et al.
DOI:——
日期:——
Aqueous DABCO, an efficient medium for rapid organocatalyzed Knoevenagel condensation and the Gewald reaction
作者:Mohammad Saeed ABAEE、Somayeh CHERAGHI
DOI:10.3906/kim-1309-38
日期:——
presence of water and 1,4-diazabicyclo[2.2.2]octane, several aldehydes and cyclic ketones underwent efficient Knoevenagel condensation with malononitrile and ethyl cyanoacetate to produce the respective a.b-unsaturated systems within fairly short time periods. As a result, high yields of conjugated products were easily obtained. Products could be engaged in a Gewald reaction, either stepwise or in situ, to