Collect. Czech. Chem. Commun. 1981, 46, 2421-2427

Cycloadditions of C-benzoyl-N-phenylnitrone with furocondensed derivatives

Lubor Fišera, Miloslava Dandárová, Jaroslav Kováč, Peter Mesko and Alžbeta Krutošíková

Department of Organic Chemistry, Slovak Institute of Technology, 880 37 Bratislava


Single regioisomeric cycloadduct IIa was formed in a 35% yield upon cycloaddition of the title nitrone Ia with benzofuran. The 1,3-dipolar cycloaddition proceeded with derivatives of 4-R-furo[3,2-b]pyrrole V or VI to the furan ring to form only one regioisomer VIIa or VIIIa in a high yield (93-95%). Dehydrogenation of the latter with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone led to the nitrone X or XII. Also C,N-diphenylnitrone reacted with furopyrroles to afford the cycloadduct VIIIb. Exclusively endo-cycloadducts originated; their transition state was stabilized by secondary orbital interactions.