1-AMINOCYCLOHEXENE-2,4-DICARBONITRILE DERIVATIVES - SYNTHESES AND STRUCTURAL STUDY

Substituted 1-aminocyclohexene-2,4-dicarbonitriles were obtained by re action of alpha,beta-unsaturated nitriles (two equivalents) with benzy l cyanide. By recrystallization from ethanol one diastereomeric racema te was isolated in each case. The cyclohexene structures were establis hed from spectroscopic data (IR, MS, and one- and two-dimensional NMR) . Relative stereochemical configurations and conformational preference s in the solid state of cyclohexenes 2 and 3 and propanedicarbonitrile 1 were established from X-ray crystallography. Crystals of 1 (C17H14N 2) belong to the orthorhombic space group Pbca. Cell dimensions are a = 17.168(7), b = 21.612(5), c = 7.508(2) Angstrom, V = 2785(7) Angstro m(3). Final R = 0.078 and R(w) = 0.091; 1363 reflections were observed . The compound 2 (C26H21N3) crystallizes in the monoclinic space group P2(1)/n with Z = 4. The crystal data for 2 are a = 7.743(1), b = 24.4 20(1), c = 11.164(1) Angstrom, beta = 102.65(1)degrees, V = 2059.7(3) Angstrom(3). Final R = 0.046 and R(w) = 0.059; 2701 reflections were o bserved. Crystals of 3 (C16H17N3) belong to the triclinic space group P $($) over bar$$ 1. Cell dimensions are a = 14.582(1), b = 7.283(1), c = 7.116(1) Angstrom, alpha = 110.84(0)degrees, beta = 85.92(0)degree s, gamma = 97.81(1)degrees, V = 696.9(2) Angstrom(3). Final R = 0.047 and R(w) = 0.052; 2227 reflections were observed. The cyclohexene ring in 2 and 3 exists as a sofa rather then as a half-chair conformation.