A magnetic separable sulfonic acid catalyst was prepared and applied for the synthesis of 3,6-di(pyridin-3-yl)-1H-pyrazolo[3,4-b]pyridine-5-carbonitriles via three-component reaction of 1-phenyl-3-(pyridin-3-yl)-1H-pyrazol-5-amine, β-ketonitrile and aldehydes in DES.
We have developed an efficient iron-catalyzed one-pot reaction of tryptamines, ynones and nitroolefins affording indole-tethered tetrasubstituted pyrroles in acceptable to good yields. Other aromatic and aliphatic amines can also be utilized in this process delivering corresponding highly functionalized tetrasubstituted pyrroles. Indolizino[8,7-b]indole derivatives could be obtained through TFA, TfOH or Fe(OTf)3-mediated cyclizations via dearomatization of indole. Unexpected dibrominated products, 7,9-dibromo-6,11-dihydro-5H-indolizino[8,7-b]indoles, were formed when PTAP was employed as electrophilic cyclization promoter.
One-pot synthesis of 1,2,4,5-tetra substituted imidazoles using sulfonic acid functionalized silica (SiO2-Pr-SO3H)