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Abstract
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The synthesis of chromenes and their derivatives has attracted considerable attention from organic and medicinal chemists for many years as a large number of natural products contain this heterocyclic nucleus. They are widely used as additives in food, perfumes, agrochemicals, cosmetics, pharmaceuticals [1] and in the preparations of insecticides, optical brightening agents, dispersed fluorescent and tunable dye lasers [2]. They have varied bioactivities, such as, inhibitory of platelet aggregation, antibacterial, anticancer, inhibitory of steroid 5α-reductase and inhibitory of HIV-1 protease [3]. Their properties turn chromenes very interesting targets to organic chemists, and several strategies for their synthesis were already developed [4]. In this work we wish to report a facile one-pot synthesis of 5,6,7,8-Tetrahydro-2H-Chromene-4-Carboxylates 3. Thus, reaction of dialkyl acetylenedicarboxylates 1 with 5,5-dimethyl-1,3-cyclohexanedione 2 in the presence of methylamine leads to the corresponding 5,6,7,8-Tetrahydro-2H-Chromene-4-Carboxylates 3a-c in fairly good yields
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