Reversible Alkylation of Dimedone with Aldehyde: A Neglected Way for Maximizing Selectivity of Three‐Component Reactions of Dimedone and an Aldehyde
The selectivity of a three‐component electrophilic reaction of an aldehyde with dimedone and another carbon‐based nucleophile could be improved by a reversible alkylation procedure, which involves formation, breaking and regeneration of CC bonds. In the presence of iron(III) chloride and triphenylphosphine, an analogous CC bond breaking can be observed in the reaction of 2,3,4,9‐tetrahydro‐9‐(2‐hydroxy‐4,4‐dimethyl‐6‐oxo‐1‐cyclohexen‐1‐yl)‐3,3‐dimethyl‐1H‐xanthen‐1‐one, in which the fragment of dimedone was replaced by a carbon‐based nucleophile. Inspired by this observation, some three‐component reactions of salicyldehyde and dimedone were successfully developed by using iron(III) chloride and triphenylphosphine (PPh3) as catalyst. PPh3 plays the role of hydrogen bond acceptor, which confers a good flexibility of the substrate by weakening the intramolecular hydrogen bond, allowing thus an easy interaction of the substrate with iron(III) chloride catalyst.
Document Type: Research Article
Affiliations: Institute of Physical Chemistry and Industrial Catalysis, School of Chemistry and Chemical Engineering, Hubei Key Laboratory of Material Chemistry and Service Failure, Huazhong University of Science and Technology (HUST), 1037 Luoyu road, Hongshan District, Wuhan 430074, People's Republic of China, Fax: (086)-(0)27-8754-4532
Publication date: September 17, 2012