Symmetrical and unsymmetrical 2,6-disubstituted dihydropyridines were prepared in high yields under mild conditions using the Suzuki and Stille Pd-catalyzed coupling reactions of imide-derived bisvinyl phosphates with a range of aryl, heteroaryl, and alkenyl moieties. The alkylation reaction at C-4 easily afforded original tri- and tetrasubstituted dihydropyridines. Hydrolysis of the latter under acidic condition provided efficiently either open-chain 1,5-diketones or di- or trisubstituted pyridines.
4-Chlor-3-coumarincarbaldehyde 2 or 4-azido-3-coumarincarbaldehyde 3 are converted into 1,4-benzodiazepines 9−12 by nucleophilic substitution with diamines 4−7 and subsequent cyclization with good yields. Following the same methodologies, carbaldehydes 2 or 3 when treated with 2-aminophenol 8 afforded 4-(2'-hydroxyphenyl)-amino-3-coumarincarbaldehyde 13 in good yields.
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