Reaction of N1,N2-diarylamidines with dicyanomethylene compounds

Abstract

2-Arylamino-2-(1,3-dioxo-2,3-dihydro-1H-inden-2-ylidene)ethanenitriles 6a–c together with the corresponding formanilides 7a–c have been obtained from the reaction of N¹,N²-diarylformamidines 1a–c with 2-(1,3-dioxo-2,3-dihydro-1H-inden-2-ylidene)propanedinitrile 2 in ethyl acetate solution, while the analogous N¹,N²-diarylacetamidines 8b–e with 2 gave indeno[1,2-d]azepines 17b–e and in two cases 2-arylamino-(1,3-dioxo-2,3-dihydro-1H-inden-2-ylidene)ethanenitriles 6b,c as minor products. In contrast, 2-oxospiro[(2,3-dihydro-1H-indole)-3,4′-(1′,2′,3′,4′-tetrahydropyridine)]-5′-carbonitriles 22b,c were obtained from the reaction of 8b,c with 2-(2-oxo-2,3-dihydro-1H-indol-2-ylidene)propanedinitrile 18. The structure assignment of spiro compound 22b has been confirmed on the basis of an X-ray crystal structure determination.