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Structural features of N-acylcytisines

“…Atom N12 of ring C played this role. Structures of 2-7 were confirmed by IR and PMR spectra and by an x-ray structure analysis (XSA) for N-o-bromobenzoylcytisine (4), N-p-nitrobenzoylcytisine (5), and N-crotonylcytisine (6).…”

“…On the other hand, the chiral 3,7-diazobicyclo[3.3.1]nonane skeleton is interesting for studying structural features of substituted cytisines [3][4][5][6]. Until now, a large number of cytisine derivatives with various groups on the N atom have been synthesized [7][8][9][10][11][12], including acryloyl groups [13], thiazoles, benzthiazoles [11], and 1,2,4-thiadiazole groups [12].…”

Z-and E-conformers of N-chloroacetylcytisine

“…However, it first transformed into one slightly broadened "dd" set (J = 15.4 and 6.3 Hz) upon heating the sample to 45°C and then changed at 65°C to one "ddd" set with practically the initial values of the constants: 15.5, 6.4, and 1.2 Hz. Methylene protons H-11 and H-13 appeared as eight well resolved resonances of the two conformers [4].…”

“…The point at which PMR resonances of the Z-and E-conformers coalesced upon heating was measured. The transition barrier between the conformers was estimated.Structural features of cytisine derivatives have recently become very significant [1][2][3][4][5]. Cytisine itself has an exceedingly rigid and sterically constrained structure that is well-known, e.g., from x-ray data.…”

“…The reason for this doubling was the well-known rotational isomerism around the N-12-CO amide bond [1, 4,6]. Conjugation of the carbonyl with the planar N atom leads to two rotational conformations that are designated [4] as the Z-and E-conformers.…”