organic compounds
5-Methyl-3,6,7,8a-tetrahydro-2H-diimidazo[1,2-c:1′,2′-e]pyrido[1,2-a][1,3,5]triazin-5-ium iodide
aDepartment of Chemical Technology of Drugs, Medical University of Gdańsk, 80-416 Gdańsk, Poland, and bFaculty of Chemistry, Adam Mickiewicz University, 60-780 Poznań, Poland
*Correspondence e-mail: magdan@amu.edu.pl
The structure of the title compound, C12H16N5+·I−, shows that the methylation reaction with CH3I occurred at the imine N atom at position 5 of the 3,6,7,8a-tetrahydro-2H-diimidazo[1,2-c:1′,2′-e]pyrido[1,2-a][1,3,5]triazine system. In the cation, the sp3-hybridized C atom belonging to the fused dihydropyrine and dihydro-1,3,5-triazine rings deviates by 0.514 (3) Å from the best plane defined by the remaining cationic non-H atoms. The fused dihydropyridine and dihydro-1,3,5-triazine rings are each in a half-chair conformation with the sp3-hybridized C atom as a flap. The iodide anion is 3.573 (2) Å from the methylated N atom and exhibits five short C—H⋯I− contacts with distances less than 3.16 Å. The structure has been determined from a non-merohedral twin with [−1 0 0 0 − 1 0 0.115 0 1], minor domain = 0.1559 (12).
Related literature
For the synthesis and data reported earlier for the title compound, see: Sączewski & Foks (1981). For the programs used to derive the see: Cooper et al.(2002); Farrugia (1999).
Experimental
Crystal data
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Refinement
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Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell CrysAlis PRO; data reduction: CrysAlis PRO; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) and WinGX (Farrugia, 1999); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97.
Supporting information
https://doi.org/10.1107/S1600536810019495/tk2676sup1.cif
contains datablocks global, I. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810019495/tk2676Isup2.hkl
1D and 2D NMR spectra were recorded on a Varian Unity 500 spectrometer. The title compound was prepared according to the previously described procedure (Sączewski & Foks, 1981); m.p. 492–494 K (decomp.); 1H NMR (500 MHz, DMSO-d6, see Fig. 3 for numbering scheme) δH 6.94 (1H, d, J = 7.2 Hz, H12), 6.22–6.19 (1H, ddd, J=9.8, 6.8, ~1 Hz, H10), 5.86 (1H, t, J = 1 Hz, H8a), 5.67 (1H, dd, J = 9.8, ~1 Hz, H9), 5.41–5.38 (1H, dd, J = 7.2, 6.8 Hz, H11), 4.42 (1H, dt, J = 9.3, 6.8 Hz, H2), 4.20 (1H, dt, J = 9.3, 6.8 Hz, H2), 4.01–3.83 (4H, m, H7, H6, 2xH3),3.78–3.71 (1H, m, H6), 3.49–3.43 (1H, m, H7), 3.26 (3H, s, CH3); 13C NMR (125 MHz, DMSO-d6, see Fig. 3 for numbering scheme) δC 152.6 (C4a), 145.7 (C13a), 125.4 (C12), 124.8 (C10), 113.6 (C9), 103.4 (C11), 67.0 (C8a), 51.7 (C3), 50.7 (C6), 46.6 (C2), 43.3 (C7), 33.7 (C14); IR (KBr, cm–1): 3090, 3079, 3025, 2936, 2880, 1684, 1661, 1550, 1429, 1321, 1301, 1186, 677.
The twin matrix, -1 0 0/0 - 1 0/0.115 0 1, corresponding to 180° rotation about [0 0 1]
direction has been determined with the program ROTAX (Cooper et al., 2002). For the with the SHELXL97 program (Sheldrick, 2008), the reflection data file was prepared in the HKLF 5 format using the 'Make HKLF5' function of the WinGX program (Farrugia, 1999). The overlapping reflections and those belonging to only one twin domain are used in the (HKLF 5 format of SHELXL97). Those which were excluded, 132 reflections, are partial overlaps which could not be integrated properly at the data processing stage. The BASF parameter refined at 0.1559 (12). The H atoms bonded to C atoms were placed at calculated positions, with C—H = 0.95–1.00 Å, and refined as riding on their parent atoms, with Uiso(H) = x Ueq(C), where x = 1.5 for the H atoms from the methyl group and x = 1.2 for the remaining H atoms. The maximum and minimum residual electron-density peaks of 1.74 and -1.24 eÅ-3 were located 0.72 Å and 1.84 Å from H6B and I1 atoms, respectively.Biguanide derivatives are known to possess diverse biological activities, including antidiabetic, antibacterial, germicidic, antiviral and antimalarial. On the other hand, quaternary ammonium salts constitute a well known class of bacteriostatic agents. Therefore, we have decided to synthesize some N-alkylated cyclic biguanide derivatives for biological testing, based on the previously described procedure (Sączewski & Foks, 1981) which consists in the reaction of 2,3,6,7,8a,13-hexahydropyrido[1,2-a]diimidazo[1',2'-c:1'',2''-e]-1,3,5-triazine (1) with an alkyl halide. As shown in Fig. 1, the course of the reaction of 1 with methyl iodide has not been established and two products, 2 or 3, arising from either N1 or N5 alkylation have been proposed. In this work, based on X-ray structure analysis (Fig. 2) and hetero-correlation NMR experiments (HSQC and HMBC), the structure of the title compound (2) is determined unambiguously. Regioselectivity of N-alkylation of the cyclic biguanide derivative 1 could not be predicted on the basis of calculated electrostatic potential and charge distribution. The structure of the N5 alkylated product 2 was also confirmed by 2D NMR spectroscopic data. Thus, assignment of signals observed in 1H and 13C-NMR spectra was possible using HSQC spectrum (see numbering scheme in Fig. 3). The crucial signals of quaternary carbon atoms C13a and C4a were found at 145.7 and 152.6 p.p.m., respectively. 3-Bond correlation from the latter carbon to a singlet of three protons at 3.26 p.p.m. observed in the HMBC spectrum (Fig. 4) indicated the placement of methyl group at the N5 nitrogen atom.
For the synthesis and data reported earlier for the title compound, see: Sączewski & Foks (1981). For the programs used to derive the
see: Cooper et al.(2002); Farrugia (1999).Data collection: CrysAlis PRO (Oxford Diffraction, 2009); cell
CrysAlis PRO (Oxford Diffraction, 2009); data reduction: CrysAlis PRO (Oxford Diffraction, 2009); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008) and WinGX (Farrugia, 1999); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).C12H16N5+·I− | F(000) = 704 |
Mr = 357.20 | Dx = 1.765 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 19213 reflections |
a = 7.6299 (2) Å | θ = 2.7–32.3° |
b = 15.3939 (4) Å | µ = 2.37 mm−1 |
c = 11.4503 (3) Å | T = 100 K |
β = 92.204 (2)° | Block, colourless |
V = 1343.89 (6) Å3 | 0.2 × 0.2 × 0.1 mm |
Z = 4 |
Oxford Diffraction Xcalibur-E CCD diffractometer | 4406 independent reflections |
Radiation source: fine-focus sealed tube | 4018 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.026 |
ω scan | θmax = 32.4°, θmin = 4.1° |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | h = −9→11 |
Tmin = 0.496, Tmax = 0.789 | k = −23→23 |
25955 measured reflections | l = 0→16 |
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.029 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.070 | H-atom parameters constrained |
S = 1.20 | w = 1/[σ2(Fo2) + (0.0196P)2 + 3.1405P] where P = (Fo2 + 2Fc2)/3 |
4406 reflections | (Δ/σ)max = 0.001 |
165 parameters | Δρmax = 1.74 e Å−3 |
0 restraints | Δρmin = −1.24 e Å−3 |
C12H16N5+·I− | V = 1343.89 (6) Å3 |
Mr = 357.20 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 7.6299 (2) Å | µ = 2.37 mm−1 |
b = 15.3939 (4) Å | T = 100 K |
c = 11.4503 (3) Å | 0.2 × 0.2 × 0.1 mm |
β = 92.204 (2)° |
Oxford Diffraction Xcalibur-E CCD diffractometer | 4406 independent reflections |
Absorption correction: multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) | 4018 reflections with I > 2σ(I) |
Tmin = 0.496, Tmax = 0.789 | Rint = 0.026 |
25955 measured reflections |
R[F2 > 2σ(F2)] = 0.029 | 0 restraints |
wR(F2) = 0.070 | H-atom parameters constrained |
S = 1.20 | Δρmax = 1.74 e Å−3 |
4406 reflections | Δρmin = −1.24 e Å−3 |
165 parameters |
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes. |
Refinement. Refinement of F2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F2, conventional R-factors R are based on F, with F set to zero for negative F2. The threshold expression of F2 > σ(F2) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F2 are statistically about twice as large as those based on F, and R- factors based on ALL data will be even larger. |
x | y | z | Uiso*/Ueq | ||
I1 | 0.04305 (2) | 0.194494 (11) | 0.473423 (14) | 0.01657 (5) | |
N1 | 0.1806 (3) | 0.53774 (16) | 0.3251 (2) | 0.0209 (5) | |
C2 | 0.2057 (4) | 0.4944 (2) | 0.2120 (2) | 0.0222 (5) | |
H2A | 0.2910 | 0.5272 | 0.1660 | 0.027* | |
H2B | 0.0931 | 0.4914 | 0.1663 | 0.027* | |
C3 | 0.2755 (4) | 0.40179 (19) | 0.2385 (2) | 0.0206 (5) | |
H3A | 0.1869 | 0.3569 | 0.2173 | 0.025* | |
H3B | 0.3846 | 0.3898 | 0.1973 | 0.025* | |
N4 | 0.3083 (3) | 0.40681 (15) | 0.36610 (19) | 0.0155 (4) | |
N5 | 0.4690 (3) | 0.27675 (15) | 0.4159 (2) | 0.0162 (4) | |
C6 | 0.5326 (4) | 0.23510 (18) | 0.5250 (2) | 0.0189 (5) | |
H6A | 0.6623 | 0.2316 | 0.5289 | 0.023* | |
H6B | 0.4837 | 0.1759 | 0.5322 | 0.023* | |
C7 | 0.4659 (4) | 0.29506 (18) | 0.6205 (2) | 0.0201 (5) | |
H7A | 0.3677 | 0.2679 | 0.6613 | 0.024* | |
H7B | 0.5609 | 0.3097 | 0.6785 | 0.024* | |
N8 | 0.4068 (3) | 0.37245 (14) | 0.55467 (19) | 0.0147 (4) | |
C9 | 0.3144 (4) | 0.4560 (2) | 0.7238 (2) | 0.0202 (5) | |
H9 | 0.3752 | 0.4175 | 0.7759 | 0.024* | |
C10 | 0.2718 (4) | 0.5354 (2) | 0.7605 (3) | 0.0237 (6) | |
H10 | 0.2938 | 0.5510 | 0.8400 | 0.028* | |
C11 | 0.1922 (4) | 0.59810 (19) | 0.6798 (3) | 0.0237 (6) | |
H11 | 0.1462 | 0.6510 | 0.7082 | 0.028* | |
C12 | 0.1842 (4) | 0.58081 (18) | 0.5651 (3) | 0.0197 (5) | |
H12 | 0.1363 | 0.6226 | 0.5118 | 0.024* | |
N13 | 0.2459 (3) | 0.50171 (14) | 0.5233 (2) | 0.0162 (4) | |
C14 | 0.2675 (3) | 0.42666 (17) | 0.6013 (2) | 0.0151 (4) | |
H14 | 0.1556 | 0.3928 | 0.6010 | 0.018* | |
C15 | 0.3916 (3) | 0.35088 (16) | 0.4392 (2) | 0.0136 (4) | |
C16 | 0.2403 (3) | 0.48697 (17) | 0.4045 (2) | 0.0156 (5) | |
C17 | 0.4863 (4) | 0.2302 (2) | 0.3064 (3) | 0.0242 (6) | |
H17A | 0.3854 | 0.1916 | 0.2934 | 0.036* | |
H17B | 0.5944 | 0.1957 | 0.3102 | 0.036* | |
H17C | 0.4909 | 0.2719 | 0.2420 | 0.036* |
U11 | U22 | U33 | U12 | U13 | U23 | |
I1 | 0.01712 (8) | 0.01865 (8) | 0.01406 (7) | 0.00055 (6) | 0.00212 (5) | −0.00050 (6) |
N1 | 0.0239 (12) | 0.0181 (11) | 0.0207 (11) | 0.0010 (9) | −0.0007 (9) | 0.0040 (9) |
C2 | 0.0251 (14) | 0.0244 (14) | 0.0170 (12) | 0.0007 (11) | −0.0009 (10) | 0.0062 (11) |
C3 | 0.0271 (15) | 0.0233 (14) | 0.0114 (11) | 0.0015 (11) | −0.0001 (9) | 0.0007 (10) |
N4 | 0.0198 (11) | 0.0150 (10) | 0.0117 (9) | 0.0004 (8) | 0.0010 (7) | 0.0016 (8) |
N5 | 0.0174 (11) | 0.0158 (9) | 0.0155 (9) | 0.0029 (8) | 0.0033 (8) | 0.0009 (8) |
C6 | 0.0189 (13) | 0.0187 (12) | 0.0191 (12) | 0.0056 (10) | 0.0012 (9) | 0.0035 (9) |
C7 | 0.0245 (13) | 0.0194 (12) | 0.0161 (11) | 0.0044 (10) | −0.0008 (9) | 0.0045 (9) |
N8 | 0.0157 (10) | 0.0150 (9) | 0.0134 (9) | 0.0007 (8) | −0.0001 (7) | 0.0017 (7) |
C9 | 0.0213 (13) | 0.0242 (13) | 0.0152 (11) | −0.0016 (10) | 0.0003 (9) | −0.0024 (10) |
C10 | 0.0223 (14) | 0.0297 (15) | 0.0191 (13) | −0.0052 (11) | 0.0023 (10) | −0.0092 (11) |
C11 | 0.0241 (15) | 0.0162 (12) | 0.0312 (15) | −0.0029 (10) | 0.0048 (11) | −0.0088 (11) |
C12 | 0.0178 (13) | 0.0126 (11) | 0.0289 (14) | −0.0021 (9) | 0.0045 (10) | −0.0026 (10) |
N13 | 0.0212 (11) | 0.0111 (9) | 0.0164 (10) | 0.0001 (8) | 0.0001 (8) | −0.0002 (8) |
C14 | 0.0166 (12) | 0.0152 (11) | 0.0135 (11) | −0.0006 (9) | 0.0001 (8) | −0.0001 (9) |
C15 | 0.0113 (11) | 0.0147 (11) | 0.0148 (10) | −0.0024 (8) | 0.0022 (8) | 0.0012 (8) |
C16 | 0.0157 (12) | 0.0130 (11) | 0.0181 (11) | −0.0021 (9) | 0.0012 (9) | 0.0011 (9) |
C17 | 0.0316 (16) | 0.0213 (13) | 0.0201 (12) | 0.0047 (11) | 0.0075 (11) | −0.0047 (10) |
N1—C16 | 1.270 (3) | C7—H7B | 0.9900 |
N1—C2 | 1.476 (4) | N8—C15 | 1.364 (3) |
C2—C3 | 1.547 (4) | N8—C14 | 1.468 (3) |
C2—H2A | 0.9900 | C9—C10 | 1.336 (4) |
C2—H2B | 0.9900 | C9—C14 | 1.504 (4) |
C3—N4 | 1.475 (3) | C9—H9 | 0.9500 |
C3—H3A | 0.9900 | C10—C11 | 1.453 (5) |
C3—H3B | 0.9900 | C10—H10 | 0.9500 |
N4—C15 | 1.344 (3) | C11—C12 | 1.340 (4) |
N4—C16 | 1.415 (3) | C11—H11 | 0.9500 |
N5—C15 | 1.317 (3) | C12—N13 | 1.397 (3) |
N5—C17 | 1.455 (4) | C12—H12 | 0.9500 |
N5—C6 | 1.470 (3) | N13—C16 | 1.378 (3) |
C6—C7 | 1.533 (4) | N13—C14 | 1.466 (3) |
C6—H6A | 0.9900 | C14—H14 | 1.0000 |
C6—H6B | 0.9900 | C17—H17A | 0.9800 |
C7—N8 | 1.471 (3) | C17—H17B | 0.9800 |
C7—H7A | 0.9900 | C17—H17C | 0.9800 |
C16—N1—C2 | 107.1 (2) | C10—C9—C14 | 121.1 (3) |
N1—C2—C3 | 107.4 (2) | C10—C9—H9 | 119.4 |
N1—C2—H2A | 110.2 | C14—C9—H9 | 119.4 |
C3—C2—H2A | 110.2 | C9—C10—C11 | 120.5 (3) |
N1—C2—H2B | 110.2 | C9—C10—H10 | 119.7 |
C3—C2—H2B | 110.2 | C11—C10—H10 | 119.7 |
H2A—C2—H2B | 108.5 | C12—C11—C10 | 119.6 (3) |
N4—C3—C2 | 101.0 (2) | C12—C11—H11 | 120.2 |
N4—C3—H3A | 111.6 | C10—C11—H11 | 120.2 |
C2—C3—H3A | 111.6 | C11—C12—N13 | 120.4 (3) |
N4—C3—H3B | 111.6 | C11—C12—H12 | 119.8 |
C2—C3—H3B | 111.6 | N13—C12—H12 | 119.8 |
H3A—C3—H3B | 109.4 | C16—N13—C12 | 118.9 (2) |
C15—N4—C16 | 122.4 (2) | C16—N13—C14 | 118.1 (2) |
C15—N4—C3 | 129.9 (2) | C12—N13—C14 | 120.6 (2) |
C16—N4—C3 | 107.6 (2) | N13—C14—N8 | 107.0 (2) |
C15—N5—C17 | 131.1 (2) | N13—C14—C9 | 110.4 (2) |
C15—N5—C6 | 110.0 (2) | N8—C14—C9 | 111.1 (2) |
C17—N5—C6 | 118.7 (2) | N13—C14—H14 | 109.4 |
N5—C6—C7 | 103.6 (2) | N8—C14—H14 | 109.4 |
N5—C6—H6A | 111.0 | C9—C14—H14 | 109.4 |
C7—C6—H6A | 111.0 | N5—C15—N4 | 129.4 (2) |
N5—C6—H6B | 111.0 | N5—C15—N8 | 112.7 (2) |
C7—C6—H6B | 111.0 | N4—C15—N8 | 117.9 (2) |
H6A—C6—H6B | 109.0 | N1—C16—N13 | 127.0 (3) |
N8—C7—C6 | 103.0 (2) | N1—C16—N4 | 116.1 (2) |
N8—C7—H7A | 111.2 | N13—C16—N4 | 116.9 (2) |
C6—C7—H7A | 111.2 | N5—C17—H17A | 109.5 |
N8—C7—H7B | 111.2 | N5—C17—H17B | 109.5 |
C6—C7—H7B | 111.2 | H17A—C17—H17B | 109.5 |
H7A—C7—H7B | 109.1 | N5—C17—H17C | 109.5 |
C15—N8—C14 | 117.1 (2) | H17A—C17—H17C | 109.5 |
C15—N8—C7 | 108.2 (2) | H17B—C17—H17C | 109.5 |
C14—N8—C7 | 119.1 (2) |
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3B···I1i | 0.99 | 3.15 | 4.007 (3) | 145 |
C6—H6A···I1ii | 0.99 | 3.05 | 4.010 (3) | 163 |
C9—H9···I1iii | 0.95 | 3.08 | 4.025 (3) | 172 |
C12—H12···I1iv | 0.95 | 3.14 | 3.887 (3) | 137 |
C17—H17C···I1i | 0.98 | 3.16 | 4.025 (3) | 148 |
Symmetry codes: (i) x+1/2, −y+1/2, z−1/2; (ii) x+1, y, z; (iii) x+1/2, −y+1/2, z+1/2; (iv) −x, −y+1, −z+1. |
Experimental details
Crystal data | |
Chemical formula | C12H16N5+·I− |
Mr | 357.20 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 100 |
a, b, c (Å) | 7.6299 (2), 15.3939 (4), 11.4503 (3) |
β (°) | 92.204 (2) |
V (Å3) | 1343.89 (6) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 2.37 |
Crystal size (mm) | 0.2 × 0.2 × 0.1 |
Data collection | |
Diffractometer | Oxford Diffraction Xcalibur-E CCD |
Absorption correction | Multi-scan (CrysAlis PRO; Oxford Diffraction, 2009) |
Tmin, Tmax | 0.496, 0.789 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 25955, 4406, 4018 |
Rint | 0.026 |
(sin θ/λ)max (Å−1) | 0.753 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.029, 0.070, 1.20 |
No. of reflections | 4406 |
No. of parameters | 165 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 1.74, −1.24 |
Computer programs: CrysAlis PRO (Oxford Diffraction, 2009), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008) and WinGX (Farrugia, 1999), ORTEP-3 for Windows (Farrugia, 1997), SHELXL97 (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3B···I1i | 0.99 | 3.15 | 4.007 (3) | 145 |
C6—H6A···I1ii | 0.99 | 3.05 | 4.010 (3) | 163 |
C9—H9···I1iii | 0.95 | 3.08 | 4.025 (3) | 172 |
C12—H12···I1iv | 0.95 | 3.14 | 3.887 (3) | 137 |
C17—H17C···I1i | 0.98 | 3.16 | 4.025 (3) | 148 |
Symmetry codes: (i) x+1/2, −y+1/2, z−1/2; (ii) x+1, y, z; (iii) x+1/2, −y+1/2, z+1/2; (iv) −x, −y+1, −z+1. |
References
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Sączewski, F. & Foks, H. (1981). Synthesis, pp. 151–152. Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
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Biguanide derivatives are known to possess diverse biological activities, including antidiabetic, antibacterial, germicidic, antiviral and antimalarial. On the other hand, quaternary ammonium salts constitute a well known class of bacteriostatic agents. Therefore, we have decided to synthesize some N-alkylated cyclic biguanide derivatives for biological testing, based on the previously described procedure (Sączewski & Foks, 1981) which consists in the reaction of 2,3,6,7,8a,13-hexahydropyrido[1,2-a]diimidazo[1',2'-c:1'',2''-e]-1,3,5-triazine (1) with an alkyl halide. As shown in Fig. 1, the course of the reaction of 1 with methyl iodide has not been established and two products, 2 or 3, arising from either N1 or N5 alkylation have been proposed. In this work, based on X-ray structure analysis (Fig. 2) and hetero-correlation NMR experiments (HSQC and HMBC), the structure of the title compound (2) is determined unambiguously. Regioselectivity of N-alkylation of the cyclic biguanide derivative 1 could not be predicted on the basis of calculated electrostatic potential and charge distribution. The structure of the N5 alkylated product 2 was also confirmed by 2D NMR spectroscopic data. Thus, assignment of signals observed in 1H and 13C-NMR spectra was possible using HSQC spectrum (see numbering scheme in Fig. 3). The crucial signals of quaternary carbon atoms C13a and C4a were found at 145.7 and 152.6 p.p.m., respectively. 3-Bond correlation from the latter carbon to a singlet of three protons at 3.26 p.p.m. observed in the HMBC spectrum (Fig. 4) indicated the placement of methyl group at the N5 nitrogen atom.