β-Nitrostyrenes underwent the Diels-Alder reaction with Danishefsky’s diene to afford cyclohexenes together with the corresponding hydrolyzed products, 3-arylated 5-methoxy-4-nitrocyclohexanones. When the reaction was conducted in the presence of water, the cyclohexenes were efficiently hydrolyzed into cyclohexanones. Subsequent aromatization by heating the cyclohexanone with a catalytic amount of iodine in dimethyl sulfoxide gave 3-arylated 4-nitrophenols. The reaction of nitrostyrenes with Danishefsky’s diene could be conducted in one-pot to directly afford the corresponding nitrophenols. Moreover, a heteroaryl group such as a thienyl group could be introduced into the nitrophenol framework.
The keto diester, dimethyl (2'-oxopropylidene)propanedioate, and its new 3'-bromo derivative have been made to react with a variety of nucleophilic reagents. Low molecular weight products have been obtained efficiently by processes involving conjugate addition, Diels-Alder reaction, Diels-Alder reaction having inverse electron demand, or ene reaction. Regiochemistry of the reactions is controlled by the dominant withdrawing effect of the two geminal ester groups. The amine addition products of the bromo keto diester were found to undergo a novel secondary dehydrobromination reaction under alkaline conditions.
Sn-PILC: A novel efficient and recyclable catalyst for one-pot three component Povarov’s inverse-electron-demand hetero Diels-Alder reaction for a facile synthesis of tetrahydropyranoquinoline derivatives under neat conditions.