2,6-Di­benzyl-1,2,3,5,6,7-hexa­hydro-2,4,6,8-tetra­aza-s-indacene and 2,6-bis(4-methoxy­benzyl)-1,2,3,5,6,7-hexa­hydro-2,4,6,8-tetra­aza-s-indacene

The title compounds, C₂₂H₂₂N₄ and C₂₄H₂₆N₄O₂ [alternative names: 2,6-dibenzyl-2,3,6,7-tetrahydro-1H,5H-dipyrrolo[3,4-b; 3′,4′-e]pyrazine and 2,6-bis(4-methoxybenzyl)-2,3,6,7-tetrahydro-1H,5H-dipyrolo[3,4-b;3′,4′-e]pyrazine], two 1,2,3,5,6,7-hexa­hydro-2,4,6,8-tetra­aza-s-indacene derivatives, are both centrosymmetric and have similar S-shaped structures. In the former, there are two independent mol­ecules (A and B), both of which possess C_i symmetry. These two mol­ecules are arranged such that the benzene ring substituent of mol­ecule B is directed towards the plane of the benzene ring substituent of mol­ecule A, with a dihedral angle of 55.4 (2)° between their planes. The shortest C—H...C distance is, however, only 3.21 (1) Å. In both compounds, the benzene ring substituents are almost perpendicular to the plane of the central pyrazine ring, and the pyrrolidine rings have perfect envelope conformations. In the crystal structures of both compounds, the mol­ecules pack in a herring-bone arrangement.

S1. Comment

During attempts to prepare 1,2,3,5,6,7-hexahydro-2,4,6,8-tetraaza-s-indacene, the title compounds, (I) and (II) were synthesized by the reaction of 2,3,5,6-tetrakis(bromomethyl)pyrazine (Ferrigo et al., 1994) with the corresponding amines. Attempts were then made to deprotect the diamines, but with little success so far.

Compound (I), with bis-benzyl substituents, crystallized with two independent centrosymmetric molecules (A and B) per unit cell. The molecular structure of (I) is illustrated in Fig. 1, and selected geometric parameters are given in Table 1. The bond distances and angles are normal, when compared with values found for similar molecules in the Cambridge Structural Database (Allen, 2002).

The molecules have an S-shape, the plane of the benzene rings being almost perpendicular to the plane of the pyrazine ring. In molecule A, the dihedral angle between the C6–C11 plane and the pyrazine ring involving atom N1 is 88.2 (2)°. In molecule B, the dihedral angle involving the C26–C31 benzene ring and the pyrazine ring involving atom N21 is 88.9 (2)°. The pyrrolidine rings have perfect envelope conformations, with atoms N2 and N22 at the flaps. The two Csp³ atoms (C3 and C4a in molecule A, and C23 and C24 in molecule B; see Fig. 1) lie in the plane of the pyrazine ring. The Cremer & Pople (1975) puckering parameters Q(2) and ϕ(2) are 0.289 (3) Å and 1.9 (6)° for molecule A (atom N2), and 0.290 (3) Å and 182.1 (7)° for molecule B (atom N22).

The two molecules are arranged such that the benzene ring of molecule B (C26–C31) is directed towards the plane of the benzene ring of molecule A (C6–C11), as shown in Fig. 1. These rings are inclined to one another by 55.4 (2)°. The shortest C—H···C distance, C29—H29A···C9, is, however, only 3.21 (1) Å for H29···C9.

In the crystal, the molecules stack along the c axis, with molecules A and B in separate columns. The molecules are arranged head-to-head (or tail-to-tail) in a herringbone arrangement, as shown in Fig. 2. There are no short intermolecular contacts (< 3.2 Å) in the crystal structure, apart from the arrangement noted above.

Compound (II), with bis-methoxybenzyl substituents, also possesses C_i symmetry. The molecular structure of (II) is illustrated in Fig. 3, and selected geometric parameters are given in Table 2. The overall structure is similar to that of (I) and, again, the bond distances and angles are normal (Allen, 2002). The molecule has an S-shape (Fig. 3), the plane of the benzene ring being inclined to the plane of the pyrazine ring by 86.6 (1)°. The pyrrolidine rings have perfect envelope conformations, with atom N2 at the flap. The two Csp³ atoms (C3 and C4) lie in the plane of the pyrazine ring. The Cremer & Pople (1975) puckering parameters Q(2) and ϕ(2) are 0.288 (1) Å and 178.2 (3)°. The methoxy substituent on the benzene ring lies in the plane of the ring, with a C12—O1—C9—C10 torsion angle of −179.85 (13)°.

In the crystal of (II), the molecules stack along the c axis and are arranged head-to-head (or tail-to-tail) in a herringbone arrangement, as shown in Fig. 4. Again, there are no short intermolecular contacts (< 3.2 Å) in the crystal structure.

S2. Experimental

Compounds (I) and (II) were prepared by the reaction of 2,3,4,5-tetrakis(bromomethyl)pyrazine (Ferrigo et al., 1994) with benzylamine (for I) or 4-methoxybenzylamine (for II), both in dry methanol. Crystals suitable for X-ray analysis were obtained by slow evaporation of solutions of pure (I) and (II) in CHCl₃, after about 1 week.

S3. Refinement

For both (I) and (II), H atoms were included in calculated positions and treated as riding atoms, to ensure as high a parameters/reflections ratio as possible [C—H_aromatic = 0.95 Å and C—H_CH2 = 0.99 Å, with U_iso(H) = 1.2U_eq(C), and C—H_CH3 = 0.98 Å, with U_iso(H) = 1.5U_eq(C)].

Computing details

For both compounds, data collection: EXPOSE (Stoe & Cie, 2000); cell refinement: CELL (Stoe & Cie, 2000); data reduction: INTEGRATE (Stoe & Cie, 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: PLATON (Spek, 2003); software used to prepare material for publication: SHELXL97.

Figures

	Fig. 1. A view of (I), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) 1 − x, 2 − y, −z; (ii) −x, 1 − y, −z.]
	Fig. 2. The molecular packing of (I), viewed down the b axis. The A molecules are centered about x = 0.5.
	Fig. 3. A view of (II), showing the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. [Symmetry codes: (i) −x, 1 − y, 1 − z.]
	Fig. 4. The molecular packing of (II), viewed down the b axis.

(I) N,N'-di-N-benzylbispyrrolidino[3,4–5,6]pyrazine

Crystal data

C22H22N4	F(000) = 728
Mr = 342.44	Dx = 1.264 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71069 Å
Hall symbol: -P 2ybc	Cell parameters from 5182 reflections
a = 36.228 (3) Å	θ = 2.3–26.0°
b = 5.5729 (6) Å	µ = 0.08 mm^−1
c = 8.9677 (7) Å	T = 153 K
β = 96.205 (9)°	Plate, colourless
V = 1799.9 (3) Å^3	0.40 × 0.40 × 0.10 mm
Z = 4

Data collection

Stoe image-plate diffractometer	1882 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.087
Graphite monochromator	θmax = 26.0°, θmin = 2.3°
Detector resolution: 0.81Å pixels mm^-1	h = −44→44
ϕ scans	k = −6→6
12398 measured reflections	l = −9→10
3324 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.068	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.181	H-atom parameters constrained
S = 1.02	w = 1/[σ^2(Fo^2) + (0.0662P)^2 + 1.3228P] where P = (Fo^2 + 2Fc^2)/3
3324 reflections	(Δ/σ)max < 0.001
235 parameters	Δρmax = 0.19 e Å^−3
0 restraints	Δρmin = −0.18 e Å^−3

Special details

Experimental. Synthesis and characterization of (I). 2,3,4,5-Tetrakis(bromomethyl)pyrazine (0.50 g, 1.10 mmol) and dried methanol (25 ml) were introduced, under an atmosphere of nitrogen, into a 100 ml two-necked flask equipped with a magnetic stirring bar and an addition funnel. Benzylamine (0.71 g, 6.63 mmol) was introduced in the additional funnel, dissolved in dried methanol (50 ml) and then added dropwise to the solution, which had been cooled to −75 °C. The mixture was stirred vigorously and the temperature allowed to increase to room temperature over a 4.5 h period. The reaction mixture was stirred for 3 d at room temperature. The yellow solution was evaporated to dryness and dichloromethane (60 ml) was added to the white residue. Filtration was carried out, the organic layer was evaporated to dryness and an orange, very sticky, solid was obtained. Two flash chromatographies on silica (l=20 cm, π=3.0 cm, m=50 g) were carried out in CH₂Cl₂/acetone (8:2) and a white solid was obtained. Recrystallization in hexane with a few drops of toluene gave suitable crystals for elemental analysis. Yield: 0.05 g (13%). ¹H RMN (CDCl₃, 400 MHz): δ=7.29–7.42 (m, 10H, H5, H6, H7), δ=4.01 (s, 8H, H2), δ=3.96 (s, 4H, H3). ¹³C RMN (CDCl₃, 400 MHz): δ=153.85 (4 C, C1), δ=138.40 (2 C, C4), δ=129.11 (4 C, C5),δ=128.94 (4 C, C6), δ=127.81 (2 C, C7), δ=60.70 (2 C, C1), δ=57.81 (4 C, C2). ESI MS m/z: 381 ([M+K]⁺), 365 ([M+Na]⁺), 343 ([M+H]⁺) IR (KBR disc, cm⁻¹): 3434(w,b), 3084(w), 3061(m), 3036(m), 3021(m), 2925(m), 2913(m), 2869(m), 2803(m), 1627(w), 1493(m), 1454(s), 1380(s), 1370(m), 1330(s), 1295(m), 1274(m), 1234(w), 1222(m), 1198(w), 1170(m), 1124(s), 1095(m), 1073(m), 1024(m), 1003(w), 982(m), 955(m), 908(w), 856(m), 823(w), 758(m), 749(s), 698(s), 641(m), 594(w), 492(w), 465(m), 407(s). M.p: 171°C (Decomp.) TLC (dichloromethane/acetone [8/2]): Rf = 0.40. Elemental analysis for C₂₂H₂₂N₄ (Mr=342.44 g.mol⁻¹) Calc. (%): C: 77.16 H: 6.48 N: 16.36 Found (%): C: 77.79 H: 6.17 N: 15.47

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.51743 (7)	0.7941 (4)	0.0756 (3)	0.0331 (6)
N2	0.42069 (7)	0.8561 (5)	0.1259 (3)	0.0337 (6)
C1	0.53399 (8)	0.9340 (5)	−0.0185 (3)	0.0293 (7)
C2	0.48283 (8)	0.8674 (5)	0.0922 (3)	0.0297 (7)
C3	0.45659 (9)	0.7575 (6)	0.1901 (4)	0.0344 (7)
H3A	0.4569	0.5802	0.1837	0.041*
H3B	0.4625	0.8066	0.2961	0.041*
C4	0.57247 (9)	0.9067 (5)	−0.0620 (4)	0.0336 (7)
H4A	0.5905	0.8718	0.0263	0.040*
H4B	0.5737	0.7779	−0.1373	0.040*
C5	0.39268 (9)	0.8590 (6)	0.2322 (4)	0.0406 (8)
H5A	0.4000	0.9765	0.3128	0.049*
H5B	0.3914	0.6987	0.2789	0.049*
C6	0.35472 (9)	0.9253 (6)	0.1544 (4)	0.0364 (8)
C7	0.33596 (10)	1.1243 (6)	0.1980 (4)	0.0476 (9)
H7A	0.3467	1.2217	0.2781	0.057*
C8	0.30114 (11)	1.1832 (7)	0.1246 (5)	0.0570 (11)
H8A	0.2883	1.3210	0.1540	0.068*
C9	0.28561 (10)	1.0403 (8)	0.0096 (5)	0.0549 (10)
H9A	0.2618	1.0782	−0.0394	0.066*
C10	0.30430 (10)	0.8434 (7)	−0.0349 (4)	0.0494 (10)
H10A	0.2937	0.7472	−0.1160	0.059*
C11	0.33848 (9)	0.7864 (6)	0.0388 (4)	0.0419 (8)
H11A	0.3511	0.6480	0.0090	0.050*
N21	−0.01705 (7)	0.2962 (5)	0.0652 (3)	0.0362 (7)
N22	0.08030 (7)	0.3620 (5)	0.1902 (3)	0.0368 (7)
C21	−0.03425 (9)	0.4333 (5)	−0.0443 (4)	0.0340 (7)
C22	0.01775 (9)	0.3711 (5)	0.1066 (4)	0.0334 (7)
C23	0.04457 (9)	0.2660 (6)	0.2267 (4)	0.0375 (8)
H23A	0.0391	0.3189	0.3274	0.045*
H23B	0.0443	0.0884	0.2227	0.045*
C24	0.07269 (9)	0.5967 (6)	0.1174 (4)	0.0370 (8)
H24A	0.0902	0.6298	0.0426	0.044*
H24B	0.0742	0.7281	0.1921	0.044*
C25	0.10884 (10)	0.3692 (7)	0.3173 (4)	0.0440 (9)
H25A	0.1112	0.2088	0.3648	0.053*
H25B	0.1015	0.4847	0.3927	0.053*
C26	0.14594 (9)	0.4430 (6)	0.2682 (4)	0.0404 (8)
C27	0.16199 (9)	0.3038 (7)	0.1647 (4)	0.0449 (9)
H27A	0.1499	0.1611	0.1274	0.054*
C28	0.19537 (11)	0.3703 (7)	0.1150 (5)	0.0549 (10)
H28A	0.2061	0.2743	0.0433	0.066*
C29	0.21316 (10)	0.5770 (8)	0.1698 (5)	0.0542 (10)
H29A	0.2360	0.6237	0.1358	0.065*
C30	0.19775 (11)	0.7128 (7)	0.2728 (5)	0.0551 (10)
H30A	0.2101	0.8541	0.3108	0.066*
C31	0.16432 (11)	0.6476 (7)	0.3228 (4)	0.0492 (9)
H31A	0.1539	0.7440	0.3951	0.059*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0343 (15)	0.0292 (14)	0.0337 (17)	−0.0036 (11)	−0.0052 (11)	0.0031 (11)
N2	0.0321 (14)	0.0355 (15)	0.0330 (17)	−0.0019 (11)	0.0015 (11)	0.0041 (11)
C1	0.0338 (16)	0.0258 (15)	0.0263 (19)	−0.0037 (13)	−0.0052 (12)	0.0003 (12)
C2	0.0325 (17)	0.0289 (16)	0.0258 (19)	−0.0028 (12)	−0.0058 (12)	−0.0010 (12)
C3	0.0363 (18)	0.0349 (18)	0.030 (2)	−0.0024 (13)	−0.0030 (13)	0.0039 (13)
C4	0.0355 (17)	0.0278 (16)	0.037 (2)	−0.0019 (13)	0.0003 (13)	0.0019 (13)
C5	0.0395 (18)	0.048 (2)	0.035 (2)	−0.0015 (15)	0.0056 (14)	0.0032 (15)
C6	0.0351 (17)	0.0416 (19)	0.034 (2)	−0.0033 (15)	0.0109 (14)	0.0037 (15)
C7	0.050 (2)	0.043 (2)	0.049 (3)	−0.0001 (17)	0.0034 (17)	−0.0066 (16)
C8	0.050 (2)	0.052 (2)	0.069 (3)	0.0170 (19)	0.009 (2)	−0.004 (2)
C9	0.039 (2)	0.068 (3)	0.058 (3)	0.0047 (19)	0.0070 (17)	−0.003 (2)
C10	0.0370 (19)	0.064 (3)	0.048 (3)	−0.0028 (17)	0.0070 (16)	−0.0103 (18)
C11	0.0392 (19)	0.044 (2)	0.043 (2)	0.0030 (15)	0.0073 (15)	−0.0044 (16)
N21	0.0396 (16)	0.0333 (14)	0.0377 (18)	0.0090 (12)	0.0123 (12)	0.0044 (12)
N22	0.0373 (15)	0.0362 (15)	0.0373 (18)	0.0056 (12)	0.0064 (12)	0.0058 (12)
C21	0.0375 (17)	0.0284 (16)	0.038 (2)	0.0067 (13)	0.0122 (14)	0.0016 (14)
C22	0.0374 (18)	0.0314 (17)	0.034 (2)	0.0060 (13)	0.0139 (13)	0.0019 (13)
C23	0.0409 (19)	0.0353 (18)	0.038 (2)	0.0051 (14)	0.0128 (14)	0.0060 (14)
C24	0.0407 (18)	0.0332 (18)	0.038 (2)	0.0025 (14)	0.0089 (14)	0.0033 (14)
C25	0.050 (2)	0.046 (2)	0.035 (2)	0.0079 (16)	0.0050 (15)	0.0022 (16)
C26	0.0431 (19)	0.0404 (19)	0.036 (2)	0.0067 (15)	−0.0020 (14)	0.0056 (15)
C27	0.039 (2)	0.046 (2)	0.048 (2)	0.0096 (16)	−0.0003 (15)	−0.0002 (17)
C28	0.043 (2)	0.065 (3)	0.056 (3)	0.0115 (19)	0.0036 (17)	−0.006 (2)
C29	0.0332 (19)	0.069 (3)	0.058 (3)	0.0030 (19)	−0.0055 (17)	0.011 (2)
C30	0.051 (2)	0.047 (2)	0.065 (3)	−0.0032 (18)	−0.0049 (19)	0.000 (2)
C31	0.056 (2)	0.046 (2)	0.045 (2)	0.0055 (18)	0.0002 (17)	−0.0016 (17)

Geometric parameters (Å, º)

N1—C1	1.338 (4)	N21—C21	1.343 (4)
N1—C2	1.342 (4)	N21—C22	1.342 (4)
N2—C5	1.466 (4)	N22—C25	1.454 (4)
N2—C3	1.471 (4)	N22—C23	1.470 (4)
N2—C4^i	1.472 (4)	N22—C24	1.475 (4)
C1—C2^i	1.395 (4)	C21—C22^ii	1.389 (4)
C1—C4	1.495 (4)	C21—C24^ii	1.483 (5)
C2—C1^i	1.395 (4)	C22—C21^ii	1.389 (4)
C2—C3	1.493 (5)	C22—C23	1.491 (5)
C3—H3A	0.9900	C23—H23A	0.9900
C3—H3B	0.9900	C23—H23B	0.9900
C4—N2^i	1.472 (4)	C24—C21^ii	1.483 (5)
C4—H4A	0.9900	C24—H24A	0.9900
C4—H4B	0.9900	C24—H24B	0.9900
C5—C6	1.519 (5)	C25—C26	1.516 (5)
C5—H5A	0.9900	C25—H25A	0.9900
C5—H5B	0.9900	C25—H25B	0.9900
C6—C11	1.375 (5)	C26—C31	1.383 (5)
C6—C7	1.379 (5)	C26—C27	1.385 (5)
C7—C8	1.397 (5)	C27—C28	1.384 (5)
C7—H7A	0.9500	C27—H27A	0.9500
C8—C9	1.374 (6)	C28—C29	1.384 (6)
C8—H8A	0.9500	C28—H28A	0.9500
C9—C10	1.371 (5)	C29—C30	1.359 (6)
C9—H9A	0.9500	C29—H29A	0.9500
C10—C11	1.376 (5)	C30—C31	1.385 (6)
C10—H10A	0.9500	C30—H30A	0.9500
C11—H11A	0.9500	C31—H31A	0.9500
C1—N1—C2	112.4 (3)	C22—N21—C21	111.9 (3)
C5—N2—C3	113.2 (3)	C25—N22—C23	113.8 (3)
C5—N2—C4^i	113.6 (3)	C25—N22—C24	113.9 (3)
C3—N2—C4^i	108.0 (2)	C23—N22—C24	107.1 (2)
N1—C1—C2^i	124.0 (3)	N21—C22—C21^ii	124.4 (3)
N1—C1—C4	126.8 (3)	N21—C22—C23	126.7 (3)
C2^i—C1—C4	109.2 (3)	C21^ii—C22—C23	108.9 (3)
N1—C2—C1^i	123.7 (3)	N22—C23—C22	102.5 (2)
N1—C2—C3	127.0 (3)	N22—C23—H23A	111.3
C1^i—C2—C3	109.3 (3)	C22—C23—H23A	111.3
N2—C3—C2	102.1 (2)	N22—C23—H23B	111.3
N2—C3—H3A	111.4	C22—C23—H23B	111.3
C2—C3—H3A	111.4	H23A—C23—H23B	109.2
N2—C3—H3B	111.4	N21—C21—C22^ii	123.7 (3)
C2—C3—H3B	111.4	N21—C21—C24^ii	126.8 (3)
H3A—C3—H3B	109.2	C22^ii—C21—C24^ii	109.6 (3)
N2^i—C4—C1	102.2 (2)	N22—C24—C21^ii	102.6 (2)
N2^i—C4—H4A	111.3	N22—C24—H24A	111.3
C1—C4—H4A	111.3	C21^ii—C24—H24A	111.3
N2^i—C4—H4B	111.3	N22—C24—H24B	111.3
C1—C4—H4B	111.3	C21^ii—C24—H24B	111.3
H4A—C4—H4B	109.2	H24A—C24—H24B	109.2
N2—C5—C6	111.1 (3)	N22—C25—C26	111.0 (3)
N2—C5—H5A	109.4	N22—C25—H25A	109.4
C6—C5—H5A	109.4	C26—C25—H25A	109.4
N2—C5—H5B	109.4	N22—C25—H25B	109.4
C6—C5—H5B	109.4	C26—C25—H25B	109.4
H5A—C5—H5B	108.0	H25A—C25—H25B	108.0
C11—C6—C7	118.9 (3)	C31—C26—C27	118.6 (3)
C11—C6—C5	120.1 (3)	C31—C26—C25	121.9 (3)
C7—C6—C5	121.0 (3)	C27—C26—C25	119.5 (3)
C6—C7—C8	120.2 (4)	C28—C27—C26	120.7 (4)
C6—C7—H7A	119.9	C28—C27—H27A	119.6
C8—C7—H7A	119.9	C26—C27—H27A	119.6
C9—C8—C7	119.5 (4)	C27—C28—C29	119.9 (4)
C9—C8—H8A	120.2	C27—C28—H28A	120.1
C7—C8—H8A	120.2	C29—C28—H28A	120.1
C10—C9—C8	120.5 (4)	C30—C29—C28	119.7 (4)
C10—C9—H9A	119.8	C30—C29—H29A	120.2
C8—C9—H9A	119.8	C28—C29—H29A	120.2
C9—C10—C11	119.5 (4)	C29—C30—C31	120.8 (4)
C9—C10—H10A	120.3	C29—C30—H30A	119.6
C11—C10—H10A	120.3	C31—C30—H30A	119.6
C6—C11—C10	121.4 (3)	C26—C31—C30	120.4 (4)
C6—C11—H11A	119.3	C26—C31—H31A	119.8
C10—C11—H11A	119.3	C30—C31—H31A	119.8
C2—N1—C1—C2^i	−0.5 (5)	C21—N21—C22—C21^ii	0.0 (5)
C2—N1—C1—C4	179.5 (3)	C21—N21—C22—C23	178.5 (3)
C1—N1—C2—C1^i	0.5 (5)	C25—N22—C23—C22	156.8 (3)
C1—N1—C2—C3	−178.8 (3)	C24—N22—C23—C22	29.9 (3)
C5—N2—C3—C2	−156.7 (3)	N21—C22—C23—N22	162.3 (3)
C4^i—N2—C3—C2	−29.9 (3)	C21^ii—C22—C23—N22	−19.1 (3)
N1—C2—C3—N2	−161.8 (3)	C22—N21—C21—C22^ii	0.0 (5)
C1^i—C2—C3—N2	18.8 (3)	C22—N21—C21—C24^ii	179.9 (3)
N1—C1—C4—N2^i	−163.0 (3)	C25—N22—C24—C21^ii	−156.0 (3)
C2^i—C1—C4—N2^i	17.0 (3)	C23—N22—C24—C21^ii	−29.2 (3)
C3—N2—C5—C6	−171.2 (3)	C23—N22—C25—C26	173.6 (3)
C4^i—N2—C5—C6	65.1 (4)	C24—N22—C25—C26	−63.2 (4)
N2—C5—C6—C11	59.6 (4)	N22—C25—C26—C31	119.1 (4)
N2—C5—C6—C7	−120.4 (4)	N22—C25—C26—C27	−60.3 (4)
C11—C6—C7—C8	−0.3 (6)	C31—C26—C27—C28	−1.1 (5)
C5—C6—C7—C8	179.7 (3)	C25—C26—C27—C28	178.3 (3)
C6—C7—C8—C9	0.5 (6)	C26—C27—C28—C29	0.5 (6)
C7—C8—C9—C10	−1.1 (6)	C27—C28—C29—C30	0.3 (6)
C8—C9—C10—C11	1.5 (6)	C28—C29—C30—C31	−0.4 (6)
C7—C6—C11—C10	0.7 (5)	C27—C26—C31—C30	1.0 (5)
C5—C6—C11—C10	−179.3 (3)	C25—C26—C31—C30	−178.4 (3)
C9—C10—C11—C6	−1.3 (6)	C29—C30—C31—C26	−0.3 (6)

Symmetry codes: (i) −x+1, −y+2, −z; (ii) −x, −y+1, −z.

(II) N,N'-di-4'-methoxybenzylbispyrrolidino[2,3–5,6]pyrazine

Crystal data

C24H26N4O2	F(000) = 428
Mr = 402.49	Dx = 1.308 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 3858 reflections
a = 20.852 (2) Å	θ = 2.9–25.9°
b = 5.6574 (5) Å	µ = 0.09 mm^−1
c = 8.6905 (9) Å	T = 153 K
β = 94.400 (13)°	Plate, colourless
V = 1022.17 (18) Å^3	0.50 × 0.40 × 0.10 mm
Z = 2

Data collection

Stoe image-plate diffractometer	1152 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tube	Rint = 0.075
Graphite monochromator	θmax = 25.9°, θmin = 2.9°
Detector resolution: 0.81Å pixels mm^-1	h = −25→25
ϕ scans	k = −6→6
7540 measured reflections	l = −10→10
1985 independent reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.030	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.071	H-atom parameters constrained
S = 0.81	w = 1/[σ^2(Fo^2) + (0.0278P)^2] where P = (Fo^2 + 2Fc^2)/3
1985 reflections	(Δ/σ)max < 0.001
137 parameters	Δρmax = 0.14 e Å^−3
0 restraints	Δρmin = −0.13 e Å^−3

Special details

Experimental. Synthesis and charaterization of II − 2,3,4,5-tetrakis(bromomethyl)pyrazine (1.00 g, 2.20 mmol) and dry methanol (50 ml) were introduced, under an atmosphere of nitrogen, into a 200 ml two-necked flask equipped with a magnetic stirring bar and a addition funnel. 4-Methoxybenzylamine (1.82 g, 13.26 mmol) was introduced into the addition funnel, dissolved in dried methanol (100 ml) and then added dropwise to the solution, which had been cooled to −75 °C. The mixture was stirred vigorously and the temperature allowed to increase to room temperature over 6 h and then left at this temperature for a further 16 h. The yellow solution was evaporated to dryness and dichloromethane (120 ml) was added to the white residue. Filtration was carried out and the orange filtrate was washed with water (60 ml). After separation, the organic layer was evaporated to dryness and a white slightly orange solid was obtained. A chromatographic column on silica (l=40 cm; π=4 cm; m=180 g) was carried out in dichloromethane/acetone (8/2) and then a gradient of acetone. A white slightly yellowish solid was obtained. Recrystallization in hexane and a few drops of toluene gave suitable crystals for elementaL analysis. Yield: 0.24 g (27%) ¹H-RMN (CDCl₃, 400 MHz): δ=7.31 (d, 4H, 3 J(5,6)=8.71 Hz, H5), δ=6.90 (d, 4H, 3 J(6,5)=8.71 Hz, H6), δ=3.98 (s, 8H, H2), δ=3.89 (s, 4H,, H3), δ=3.82 (s, 6H, H8). ¹³C-RMN (CDCl₃, 400 MHz): δ=158.87 (2 C, C7), δ=153.40 (4 C, C1), δ=129.85 (4 C, C5), δ=129.32 (2 C, C4), δ=113.84 (4 C, C6), δ=59.59 (2 C, C3), δ=57.24 (4 C, C2), δ=55.23 (2 C, C8). ESI MS m/z: 425 ([M+Na]⁺), 425 ([M+Na]⁺). IR (KBR disc, cm⁻¹): 3444(w,b), 3058(w), 3004(w), 2913(m), 2870(w), 2836(w), 2813(m), 2785(m), 1612(m), 1584(m), 1511(s), 1468(m), 1455(m), 1440(m), 1419(w), 1380(m), 1331(s), 1302(m), 1276(m), 1248(s), 1232(m), 1182(m), 1170(m), 1126(s), 1106(m), 1092(m), 1035(s), 1008(w), 983(w), 954(w), 928(w), 861(m), 844(w), 832(m), 823(m), 815(m), 809(s), 758(m), 765(w), 644(w), 628(m), 551(w), 515(w), 492(w), 408(m). M.p: 205°C (Decomp.) TLC (dichloromethane/acetone [8/2]): Rf = 0.30. Elemental analysis for C₂₄H₂₆N₄O₂ (Mr=402.50 g.mol⁻¹) Calc. (%): C: 71.62 H: 6.51 N: 13.92 Found (%): C: 71.35 H: 6.13 N: 12.94

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
N1	0.02874 (6)	0.29821 (19)	0.43075 (13)	0.0303 (3)
N2	0.13998 (5)	0.63200 (19)	0.68317 (13)	0.0312 (3)
O1	0.43397 (5)	0.43264 (18)	0.59316 (13)	0.0441 (3)
C1	−0.03123 (7)	0.3734 (2)	0.39221 (15)	0.0279 (3)
C2	0.05918 (7)	0.4316 (2)	0.54078 (16)	0.0279 (3)
C3	0.12628 (7)	0.4008 (2)	0.61036 (17)	0.0333 (3)
H3A	0.1289	0.2720	0.6878	0.040*
H3B	0.1563	0.3666	0.5304	0.040*
C4	0.07825 (7)	0.7301 (2)	0.72641 (16)	0.0322 (3)
H4A	0.0782	0.9049	0.7212	0.039*
H4B	0.0690	0.6800	0.8316	0.039*
C5	0.18961 (7)	0.6244 (3)	0.81087 (17)	0.0369 (4)
H5A	0.1779	0.5043	0.8867	0.044*
H5B	0.1919	0.7798	0.8633	0.044*
C6	0.25449 (7)	0.5652 (2)	0.75635 (16)	0.0324 (3)
C7	0.28904 (7)	0.3675 (3)	0.80777 (17)	0.0381 (4)
H7A	0.2711	0.2643	0.8794	0.046*
C8	0.34930 (7)	0.3159 (3)	0.75735 (18)	0.0395 (4)
H8A	0.3723	0.1802	0.7949	0.047*
C9	0.37524 (7)	0.4645 (3)	0.65193 (17)	0.0343 (4)
C10	0.34126 (7)	0.6627 (3)	0.59863 (18)	0.0367 (4)
H10A	0.3588	0.7644	0.5257	0.044*
C11	0.28208 (7)	0.7123 (3)	0.65137 (17)	0.0354 (4)
H11A	0.2596	0.8500	0.6153	0.043*
C12	0.47052 (8)	0.2309 (3)	0.6444 (2)	0.0540 (5)
H12C	0.5119	0.2317	0.5978	0.065*
H12B	0.4468	0.0869	0.6136	0.065*
H12A	0.4781	0.2353	0.7570	0.065*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0372 (7)	0.0251 (6)	0.0303 (6)	−0.0048 (5)	0.0142 (5)	−0.0035 (5)
N2	0.0354 (7)	0.0283 (6)	0.0309 (7)	−0.0031 (5)	0.0089 (5)	−0.0059 (5)
O1	0.0356 (6)	0.0490 (6)	0.0480 (7)	0.0032 (5)	0.0050 (5)	0.0023 (6)
C1	0.0368 (8)	0.0226 (7)	0.0263 (7)	−0.0046 (6)	0.0152 (6)	−0.0016 (6)
C2	0.0348 (8)	0.0229 (7)	0.0276 (8)	−0.0048 (6)	0.0134 (6)	0.0001 (6)
C3	0.0414 (9)	0.0253 (7)	0.0347 (8)	−0.0028 (6)	0.0121 (6)	−0.0034 (7)
C4	0.0403 (9)	0.0275 (7)	0.0303 (7)	−0.0039 (6)	0.0131 (6)	−0.0048 (7)
C5	0.0445 (9)	0.0373 (8)	0.0296 (8)	−0.0036 (7)	0.0067 (7)	−0.0021 (7)
C6	0.0376 (8)	0.0314 (8)	0.0279 (8)	−0.0033 (6)	0.0016 (6)	−0.0036 (7)
C7	0.0487 (10)	0.0338 (8)	0.0326 (8)	−0.0031 (7)	0.0075 (7)	0.0034 (7)
C8	0.0483 (10)	0.0312 (8)	0.0386 (9)	0.0028 (7)	0.0015 (7)	0.0018 (7)
C9	0.0314 (8)	0.0372 (8)	0.0341 (9)	−0.0020 (6)	0.0008 (6)	−0.0044 (7)
C10	0.0365 (9)	0.0369 (8)	0.0362 (8)	−0.0063 (7)	0.0004 (7)	0.0065 (7)
C11	0.0371 (9)	0.0323 (8)	0.0362 (8)	−0.0007 (6)	−0.0010 (7)	0.0031 (7)
C12	0.0459 (10)	0.0492 (10)	0.0669 (12)	0.0104 (8)	0.0041 (9)	−0.0035 (10)

Geometric parameters (Å, º)

N1—C1	1.3389 (17)	C5—C6	1.505 (2)
N1—C2	1.3392 (18)	C5—H5A	0.9900
N2—C5	1.4588 (18)	C5—H5B	0.9900
N2—C3	1.4716 (17)	C6—C7	1.386 (2)
N2—C4	1.4764 (17)	C6—C11	1.392 (2)
O1—C9	1.3744 (18)	C7—C8	1.393 (2)
O1—C12	1.4247 (18)	C7—H7A	0.9500
C1—C2^i	1.3956 (18)	C8—C9	1.384 (2)
C1—C4^i	1.487 (2)	C8—H8A	0.9500
C2—C1^i	1.3956 (18)	C9—C10	1.387 (2)
C2—C3	1.491 (2)	C10—C11	1.378 (2)
C3—H3A	0.9900	C10—H10A	0.9500
C3—H3B	0.9900	C11—H11A	0.9500
C4—C1^i	1.487 (2)	C12—H12C	0.9800
C4—H4A	0.9900	C12—H12B	0.9800
C4—H4B	0.9900	C12—H12A	0.9800
C1—N1—C2	112.46 (11)	C6—C5—H5B	109.3
C5—N2—C3	113.82 (11)	H5A—C5—H5B	107.9
C5—N2—C4	113.51 (11)	C7—C6—C11	117.61 (14)
C3—N2—C4	107.41 (10)	C7—C6—C5	122.39 (13)
C9—O1—C12	117.36 (12)	C11—C6—C5	120.00 (13)
N1—C1—C2^i	123.97 (12)	C6—C7—C8	121.79 (14)
N1—C1—C4^i	126.99 (11)	C6—C7—H7A	119.1
C2^i—C1—C4^i	109.04 (12)	C8—C7—H7A	119.1
N1—C2—C1^i	123.58 (13)	C9—C8—C7	119.26 (14)
N1—C2—C3	127.03 (12)	C9—C8—H8A	120.4
C1^i—C2—C3	109.40 (12)	C7—C8—H8A	120.4
N2—C3—C2	102.45 (11)	O1—C9—C8	124.82 (13)
N2—C3—H3A	111.3	O1—C9—C10	115.40 (13)
C2—C3—H3A	111.3	C8—C9—C10	119.79 (14)
N2—C3—H3B	111.3	C11—C10—C9	120.07 (14)
C2—C3—H3B	111.3	C11—C10—H10A	120.0
H3A—C3—H3B	109.2	C9—C10—H10A	120.0
N2—C4—C1^i	102.53 (11)	C10—C11—C6	121.48 (14)
N2—C4—H4A	111.3	C10—C11—H11A	119.3
C1^i—C4—H4A	111.3	C6—C11—H11A	119.3
N2—C4—H4B	111.3	O1—C12—H12C	109.5
C1^i—C4—H4B	111.3	O1—C12—H12B	109.5
H4A—C4—H4B	109.2	H12C—C12—H12B	109.5
N2—C5—C6	111.68 (12)	O1—C12—H12A	109.5
N2—C5—H5A	109.3	H12C—C12—H12A	109.5
C6—C5—H5A	109.3	H12B—C12—H12A	109.5
N2—C5—H5B	109.3
C2—N1—C1—C2^i	−0.19 (19)	N2—C5—C6—C11	60.50 (18)
C2—N1—C1—C4^i	179.17 (12)	C11—C6—C7—C8	0.1 (2)
C1—N1—C2—C1^i	0.19 (19)	C5—C6—C7—C8	−179.44 (14)
C1—N1—C2—C3	−179.49 (13)	C6—C7—C8—C9	−0.6 (2)
C5—N2—C3—C2	155.61 (11)	C12—O1—C9—C8	0.3 (2)
C4—N2—C3—C2	29.07 (14)	C12—O1—C9—C10	−179.85 (13)
N1—C2—C3—N2	162.58 (12)	C7—C8—C9—O1	−179.81 (14)
C1^i—C2—C3—N2	−17.14 (14)	C7—C8—C9—C10	0.3 (2)
C5—N2—C4—C1^i	−156.46 (11)	O1—C9—C10—C11	−179.40 (13)
C3—N2—C4—C1^i	−29.73 (14)	C8—C9—C10—C11	0.5 (2)
C3—N2—C5—C6	66.95 (15)	C9—C10—C11—C6	−1.0 (2)
C4—N2—C5—C6	−169.77 (11)	C7—C6—C11—C10	0.7 (2)
N2—C5—C6—C7	−119.98 (15)	C5—C6—C11—C10	−179.72 (13)

Symmetry code: (i) −x, −y+1, −z+1.