Sodium Dodecyl Sulphate Catalyzed One-Pot Three-Component Synthesis of Structurally Diverse 2-Amino-3-cyano Substituted Tetrahydrobenzo[ b ]pyrans and Spiropyrans in Water at Room Temperature

A facile and convenient method has been developed for the one-pot three-component synthesis of 2-amino-3-cyano substituted tetrahydrobenzo[ b ]pyran derivatives from the reactions of aromatic aldehydes, malononitrile and dimedone or 1,3-cyclohexanedione in the presence of a catalytic amount of sodium dodecyl sulphate as an efficient surfactant type catalyst in water at room temperature. Synthesis of 2-amino-3-cyano substituted spiropyrans was also achieved under the same reaction conditions starting from ninhydrin/isatins, malononitrile and dimedone or 1,3-cyclohexanedione. All the reactions were completed within 2.5 h and the desired products afforded in good to excellent yields. Gram scale production of the desired compound was also achieved. Use of water as green solvent, commercially available low cost surfactant type catalyst, high atom economy, excellent yields, energy efficiency, no column chromatographic purifications, reusability of the solvent media, multiple carbon–carbon and carbon-heteroatom bond formations are some of the major advantages of this newly developed protocol. Graphical Abstract