Pyrroles from ketoximes and acetylene. 11. Conformation of 1-vinylpyrroles from1H NMR data

A number of 1-vinylpyrroles were studied by PMR spectroscopy. Bulky substituents in the position of the pyrrole ring give rise to deshielding of h_b and a decrease in²J(H_A,H_B) and⁶J(H₃,H_B). The results were interpreted as a decrease in the p, conjugation in the N-vinyl group due to distortion of the coplanarity. The dihedral angle () between the planes of the pyrrole ring and the double bond was estimated (with an accuracy of ±5 °).See 10] for our previous communication 10].Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 328–330, March, 1980