N,N,N',N'-tetramethylethylene-diaminium-N,N'-disulfonic acid chloride as a highly effective catalyst for the synthesis of 4H-pyrano[2, 3-c]pyrazoles, α-carbamatoalkyl-β-naphthols and α-amidoalkyl-β-naphthols

In this work, N,N,N',N'-tetramethylethylene-diaminium-N,N'-disulfonic acid chloride {[TMEDSA][Cl]2} has been utilized as a highly effective catalyst in order to promote the following organic transformations under green, solvent-free and mild conditions: (i) the synthesis of 4H-pyrano[2, 3-c]pyrazoles from aromatic aldehydes, 3-methyl-1-phenyl-2-pyrazolin-5-one and malononitrile, (ii) the preparation of α-carbamatoalkyl-β-naphthols from arylaldehydes, β-naphthol and alkyl carbamates, and (iii) the production of α-amidoalkyl-β-naphthols from arylaldehydes, β-naphthol and amides.