Three-Component Reactions of Aromatic Aldehydes and Two Different Nucleophiles and their Leaving Ability-Determined Downstream Conversions of the Products

Many three-component reactions of aromatic aldehydes with activated methylene derivatives and an associated nucleophile have been developed by using L-proline as the catalyst. Nucleophiles, such as indoles, thiophenols, mercaptans, 2-methylfuran and benzenesulfinic acid, could be successfully used in the reactions while the activated methylene derivatives can be 1,3-cyclohexanedione, dimedone, 1,3-cyclopentanedione, 1-phenyl-3-methyl-5-pyrazolone, 4-hydroxycoumarin, 4,6-dihydroxy-2-mercaptopyrimidine, 4-hydroxy-1-methyl-2quinolone, 4-hydroxy-6-methyl-2-pyrone and 2-hydroxy-1,4-naphthoquinone. Investigation of the downstream utilization of the products from the above multicomponent reactions (MCRs) revealed that selective cleavages of carbon-carbon and carbon-heteroatom bonds in these molecules are indeed possible, which opens an avenue to access some new S(N)1-type reactions. Particularly, when the MCR product of an aromatic aldehyde, dimedone and thiophenol was treated with an acid catalyst in the presence of an appropriate nucleophile, cleavage of the carbon-sulfur bond occurred preferentially, thus providing many complex molecules that cannot be attained by other known methods.