Palladium Catalyzed, Multicomponent Synthesis of Fused-Ring Pyrroles from Aryl Iodides, Carbon Monoxide, and Alkyne-Tethered Imines

A palladium-catalyzed multicomponent route to polycyclic pyrroles is described. Pd­(P^<i>t</i>Bu₃)₂ was found to catalyze the coupling of (hetero)­aryl iodides, two equivalents of carbon monoxide and alkyne-tethered imines into 1,3-dipoles (Münchnones), which undergo spontaneous, intramolecular 1,3-dipolar cycloaddition to form polycyclic pyrroles. The systematic variation of the alkyne, tethered-imine, or aryl iodide can allow the buildup of a range of pyrrole derivatives, where any of the substituents can be independently varied. In addition, the same palladium catalyst can be employed in an initial Sonogashira-type coupling with aryl iodides, which upon the addition of CO can allow the novel tandem catalytic, five component synthesis of diversely substituted products

Synthesis of pyrimido[4′,5′:5,6][1,4]dithiepino[2,3-b]quinoxalines: Derivatives of a novel seven membered ring system

<p></p> <p>A convenient and efficient procedure for the synthesis of tetracyclic dithiepin derivatives is described through the condensation reaction of 2,4-dichloro-5-(chloromethyl)-6- methylpyrimidine and quinoxaline-2,3-dithiol followed by treatment with secondary amines.</p