A simple, catalyst free, water mediated, one pot four component, green protocol was developed for title compounds 7 starting from aromatic aldehydes (1), malononitrile (2), 1,3-diones (3) and N-chlorosuccinimide (NCS) in a sequential addition reaction at ambient temperature. The approach presented herein, for the first time, is through an unusual rearrangement where NCS was reacted with 2-amino-7,7-dimethyl-5-oxo-4-aryl-5,6,7,8-tetrahydro-4H-chromene-3-carbonitrile (4), which was formed by the Knoevenagel condensation of aldehyde and malononitrile followed by the Michael addition of 3. In addition, this novel protocol is compatible with various aldehydes and active C-H functional derivatives, accomplishes high yields and follows the GAP chemistry principle. Interestingly, compound 4 when reacted with NCS in alcohol medium gave 2-cyano-6,6-dimethyl-4-oxo-3-aryl-2,3,4,5,6,7-hexahydrobenzofuran-2-carboxylate (5).
Synthesis of a series of novel aryl and heteroaryl fused 2,8-dioxabicyclo[3.3.1]nonanes (3) was accomplished by one pot, catalyst free reaction of 2-hydroxy chalcones (1) with 3-trifluoromethyl substituted pyrazolones (2) in xylene at reflux temperature. The role of –CF3 in formation of 3 was confirmed by comparing with 3-methyl pyrazolones.
The synthesis of 2-sulfenylimine chromene compounds (8) is accomplished by reacting benzaldehyde (1), malanonitrile (2) and dimedone (3) followed by sequential addition of N-chlorosuccinimide and thiophenols to the in situ formed 2-amino-4(H) chromenes (4) in a one pot, catalyst free, five component reaction in toluene medium. When aniline was employed as the nucleophile in place of thiophenol, the formation of hexahydrobenzofuran-2-N-phenyl carboxamide derivatives (5) was observed. Excellent yields, simple reaction conditions and high compatibility are the advantages of this protocol.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.