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A versatile and efficient single-step route to 3-cyanocoumarins via Knoevenagel condensation of salicylaldehydes and malononitrile using ZrCl 4 as the catalyst (15 mol %) in ionic liquid 1-(n-butyl)-3-methylimidazolium tetrafluoroborate as reaction medium and catalyst is described. The novel procedure features single step, short reaction time, good yields, and simple workup.

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A new method for the synthesis of (E)‐acrylates/benzylidenemalononitriles (III) and coumarins (VI) via Knoevenagel condensation of appropriate benz‐ or salicylaldehydes with active methylene compounds is described.

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A simple and efficient method was developed for the reaction of dimethyl acetylenedicarboxylate with benzothiazole, isoquinoline, quinoline, 3‐bromopyridine, pyridine, benzoxazole, benzimidazole, and 5,6‐dimethyl benzimidazole for the high‐yield synthesis of the related heterocyclic products (1, 2, 3, 4, 5, 6, 7, 8) in very short reaction time under neat procedure. The reaction of isoquinoline, 3‐bromopyridine, and pyridine afforded to diastereomeric mixtures of products 2, 4, and 5, respectively. However, only one isomer of products 1, 3, 6, 7, and 8 were identified from the reaction of benzothiazole, quinoline, benzoxazole, benzimidazole, and 5,6‐dimethyl benzimidazole, respectively. Benzotriazole afforded to product 9 under these conditions. For comparison, the reactions were examined in different reaction mediums and/or under microwave irradiation. J. Heterocyclic Chem., (2011).

1‐(4‐Nitritobutyl)‐3‐methylimidazolium chloride is used as a new ionic liquid reagent for the synthesis of N‐nitrosamines (II).