The cross-dehydrogenative coupling protocol is catalyzed by a simple iron salt, and air is used as the terminal oxidant under very mild conditions, offering a novel synthetic method for the direct construction of all-carbon quaternary centers.

A simple, green and efficient approach for one‐pot pseudo‐five‐component synthesis of the 4,4’‐(arylmethylene)bis(1H‐pyrazol‐5‐ol) derivatives from hydrazines, dialkyl acetylenedicarboxylats/β‐ketoesters and aromatic aldehydes catalyzed by Dabco‐base ionic liquids in aqueous media has been successfully developed. All the reactions were performed under 3 mol% of ionic liquid catalyst, and afforded the corresponding bis(pyrazol‐5‐ol)s in excellent yields (81‐98 %). This method also offers several other notable advantages, such as environmental friendliness, short reaction times, easy workup and reusability of the inexpensive catalyst.