In the isomeric compounds 2-benzyl-3-methyl-1-phenylbenzo[b]furo[2,3-c]pyrrole and 2-benzyl-1-methyl-3-phenylbenzo[b]furo[2,3-c]pyrrole, both C24H19NO, the pyrrole ring, although presumably somewhat strained, does not differ appreciably from N-methylpyrrole except for a relatively short C-C single bond in the pyrrole ring.
Supporting information
CCDC references: 143272; 143273
Compound (I) was prepared by our general method from 2-nitrobenzo[b]furan
and N-benzyl-N-benzoylalanine (Gribble et al., 1998), and
recrystallized from acetone-petroleum ether to give rhomboidal crystals (m.p.
389–391 K). Compound (II) was prepared similarly, from
2-nitrobenzo[b]furan and
N-acetyl-N-benzyl-α-phenylglycine, and recrystallized from
acetone-hexanes to give rhomboidal crystals (m.p. 426–427 K). The full
synthetic details will be described separately (Gribble et al., 1999).
For both compounds, data collection: MSC/AFC Diffractometer Control Software (Molecular Structure Corporation, 1994); cell refinement: MSC/AFC Diffractometer Control Software; data reduction: TEXSAN for Windows (Molecular Structure Corporation, 1999); program(s) used to solve structure: SIR97 (Altomare et al., 1997) and DIRDIF94 (Beurskens et al., 1994); program(s) used to refine structure: SHELXL93 (Sheldrick, 1993); software used to prepare material for publication: TEXSAN for Windows.
Crystal data top
C24H19NO | Z = 2 |
Mr = 337.42 | F(000) = 356.00 |
Triclinic, P1 | Dx = 1.263 Mg m−3 |
a = 10.405 (2) Å | Mo Kα radiation, λ = 0.7107 Å |
b = 11.524 (2) Å | Cell parameters from 20 reflections |
c = 9.177 (2) Å | θ = 6.3–9.3° |
α = 113.44 (1)° | µ = 0.08 mm−1 |
β = 113.94 (2)° | T = 296 K |
γ = 93.94 (2)° | Prism, light orange |
V = 887.4 (4) Å3 | 0.4 × 0.3 × 0.2 mm |
Data collection top
Rigaku AFC-6S diffractometer | Rint = 0.020 |
Radiation source: X-ray tube | θmax = 27.5°, θmin = 2.0° |
Graphite monochromator | h = 0→13 |
ω/2θ scans | k = −14→14 |
4289 measured reflections | l = −11→10 |
4067 independent reflections | 3 standard reflections every 150 reflections |
1420 reflections with I > 3σ(I) | intensity decay: −0.6% |
Refinement top
Refinement on F | 0 constraints |
Least-squares matrix: full | H-atom parameters not refined |
R[F2 > 2σ(F2)] = 0.049 | Weighting scheme based on measured s.u.'s w = 1/[σ2(Fo) + 0.00002|Fo|2] |
wR(F2) = 0.225 | (Δ/σ)max = 0.050 |
S = 1.03 | Δρmax = 0.26 e Å−3 |
4067 reflections | Δρmin = −0.22 e Å−3 |
236 parameters | Extinction correction: Zachariasen (1967), equ (3) [Zachariasen, W. H. (1968). Acta Cryst. A24, p213.] |
0 restraints | Extinction coefficient: 9.7 (7) × 10-7 |
Crystal data top
C24H19NO | γ = 93.94 (2)° |
Mr = 337.42 | V = 887.4 (4) Å3 |
Triclinic, P1 | Z = 2 |
a = 10.405 (2) Å | Mo Kα radiation |
b = 11.524 (2) Å | µ = 0.08 mm−1 |
c = 9.177 (2) Å | T = 296 K |
α = 113.44 (1)° | 0.4 × 0.3 × 0.2 mm |
β = 113.94 (2)° | |
Data collection top
Rigaku AFC-6S diffractometer | Rint = 0.020 |
4289 measured reflections | 3 standard reflections every 150 reflections |
4067 independent reflections | intensity decay: −0.6% |
1420 reflections with I > 3σ(I) | |
Refinement top
R[F2 > 2σ(F2)] = 0.049 | 0 restraints |
wR(F2) = 0.225 | H-atom parameters not refined |
S = 1.03 | Δρmax = 0.26 e Å−3 |
4067 reflections | Δρmin = −0.22 e Å−3 |
236 parameters | |
Special details top
Experimental. The scan width was (1.37 + 0.34tanθ)° with an ω scan speed of 8° per minute
[up to 5 scans to achieve I/σ(I) > 10]. Stationary background counts were
recorded at each end of the scan, and the scan time to background time ratio
was 2:1. |
Refinement. The final cycle of full-matrix least-squares refinement (SHELXL93:
Σw(Fo2-Fc2)2, where w = 1/[Σ2(Fo2) + (0.1P)2] and P =
[Max(Fo2,0) + 2Fc2)/3], was based on 1420 (I) or 1789 (II) observed
reflections and 236 (I) or 236 (II) variable parameters and converged [largest
parameter shift was 0.07 (I) or 0.00 (II) times its esd] with unweighted and
weighted agreement factors of: R1 = Σ||Fo| - |Fc||/Σ|Fo| = 0.049 (I),
0.045 (II); wR2 = [Σ(w(Fo2-Fc2)2)/Σw(Fo2)2]1/2 = 0.225(I),
0.197(II). The standard deviation of an observation of unit weight
([Σw(Fo2-Fc2)2/(No-Nv)]1/2, where No = number of observations and Nv =
number of variables) was 1.03 (I) or 1.04 (II). The weighting scheme was based
on counting statistics and included a factor [p = 0.010 (I) or 0.002 (II)] to
downweight the intense reflections. The maximum and minimum peaks on the final
difference Fourier map corresponded to 0.25 (I) and 0.24 (II), and -0.22 (I)
and -0.23 (II) eÅ-3, respectively.
Neutral atom scattering factors were taken from Cromer & Waber (1974).
Anomalous dispersion effects were included in Fcalc
(Ibers & Hamilton, 1964); the values for δf' and δf'' were those
of Creagh & McAuley (1992). The values for the mass attenuation coefficients
are those of Creagh & Hubbell (1992). |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O4 | −0.0965 (3) | 0.4103 (2) | 0.1737 (3) | 0.0596 (8) | |
N2 | 0.1967 (3) | 0.3342 (3) | 0.0792 (4) | 0.0499 (9) | |
C1 | 0.0798 (4) | 0.2939 (3) | −0.0904 (4) | 0.046 (1) | |
C3 | 0.1564 (4) | 0.3864 (3) | 0.2157 (5) | 0.051 (1) | |
C3a | 0.0129 (4) | 0.3771 (3) | 0.1250 (5) | 0.051 (1) | |
C4a | −0.2179 (4) | 0.3747 (3) | 0.0099 (5) | 0.051 (1) | |
C5 | −0.3543 (4) | 0.3918 (3) | −0.0061 (5) | 0.062 (1) | |
C6 | −0.4664 (4) | 0.3478 (3) | −0.1790 (5) | 0.062 (1) | |
C7 | −0.4432 (4) | 0.2892 (3) | −0.3274 (5) | 0.063 (1) | |
C8 | −0.3069 (4) | 0.2760 (3) | −0.3095 (4) | 0.057 (1) | |
C8a | −0.1927 (4) | 0.3195 (3) | −0.1390 (5) | 0.046 (1) | |
C8b | −0.0370 (4) | 0.3225 (3) | −0.0602 (4) | 0.0465 (9) | |
C9 | 0.3442 (3) | 0.3236 (3) | 0.1190 (4) | 0.053 (1) | |
C10 | 0.2573 (4) | 0.4413 (3) | 0.4098 (4) | 0.071 (1) | |
C11 | 0.0865 (3) | 0.2385 (3) | −0.2605 (4) | 0.050 (1) | |
C12 | 0.0029 (4) | 0.2732 (3) | −0.3927 (5) | 0.060 (1) | |
C13 | −0.0020 (4) | 0.2199 (4) | −0.5598 (5) | 0.076 (1) | |
C14 | 0.0782 (5) | 0.1327 (4) | −0.5983 (5) | 0.081 (2) | |
C15 | 0.1622 (4) | 0.0969 (4) | −0.4709 (6) | 0.074 (1) | |
C16 | 0.1652 (4) | 0.1479 (3) | −0.3046 (5) | 0.060 (1) | |
C17 | 0.3734 (4) | 0.2031 (3) | 0.1426 (4) | 0.048 (1) | |
C18 | 0.5136 (4) | 0.1897 (3) | 0.1981 (4) | 0.058 (1) | |
C19 | 0.5445 (4) | 0.0806 (4) | 0.2209 (5) | 0.074 (1) | |
C20 | 0.4352 (5) | −0.0133 (4) | 0.1898 (6) | 0.085 (2) | |
C21 | 0.2959 (5) | −0.0016 (4) | 0.1334 (5) | 0.081 (1) | |
C22 | 0.2628 (4) | 0.1063 (3) | 0.1088 (5) | 0.067 (1) | |
H3A | 0.2185 | 0.4193 | 0.4787 | 0.090* | |
H3B | 0.3506 | 0.4169 | 0.4403 | 0.090* | |
H3C | 0.2918 | 0.5401 | 0.4767 | 0.090* | |
H5 | −0.3733 | 0.4336 | 0.1021 | 0.084* | |
H6 | −0.5639 | 0.3577 | −0.1979 | 0.077* | |
H7 | −0.5285 | 0.2543 | −0.4507 | 0.085* | |
H8 | −0.2925 | 0.2348 | −0.4213 | 0.077* | |
H9A | 0.3683 | 0.3250 | 0.0258 | 0.074* | |
H9B | 0.4196 | 0.4036 | 0.2307 | 0.074* | |
H10 | 0.1640 | 0.1114 | 0.0681 | 0.082* | |
H12 | −0.0578 | 0.3355 | −0.3665 | 0.081* | |
H14 | 0.0768 | 0.0979 | −0.7194 | 0.100* | |
H13 | −0.0673 | 0.2441 | −0.6555 | 0.092* | |
H15 | 0.2233 | 0.0348 | −0.4960 | 0.094* | |
H16 | 0.2294 | 0.1233 | −0.2121 | 0.076* | |
H18 | 0.5956 | 0.2586 | 0.2221 | 0.071* | |
H19 | 0.6479 | 0.0724 | 0.2608 | 0.097* | |
H20 | 0.4605 | −0.0896 | 0.2092 | 0.104* | |
H21 | 0.2201 | −0.0724 | 0.1096 | 0.092* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O4 | 0.070 (2) | 0.055 (2) | 0.054 (2) | 0.020 (1) | 0.031 (1) | 0.023 (1) |
N2 | 0.043 (2) | 0.047 (2) | 0.053 (2) | 0.009 (2) | 0.014 (1) | 0.027 (2) |
C1 | 0.049 (2) | 0.037 (2) | 0.052 (2) | 0.009 (2) | 0.021 (1) | 0.024 (2) |
C3 | 0.055 (2) | 0.043 (2) | 0.053 (2) | 0.014 (2) | 0.022 (1) | 0.025 (2) |
C3 | 0.058 (2) | 0.043 (2) | 0.054 (2) | 0.017 (2) | 0.029 (2) | 0.023 (2) |
C4 | 0.059 (2) | 0.039 (2) | 0.060 (2) | 0.016 (2) | 0.028 (2) | 0.028 (2) |
C5 | 0.074 (2) | 0.048 (2) | 0.087 (2) | 0.025 (2) | 0.053 (2) | 0.035 (2) |
C6 | 0.054 (2) | 0.056 (3) | 0.093 (2) | 0.023 (2) | 0.040 (2) | 0.043 (2) |
C7 | 0.054 (2) | 0.061 (3) | 0.082 (3) | 0.021 (2) | 0.029 (2) | 0.043 (2) |
C8 | 0.056 (2) | 0.059 (2) | 0.058 (2) | 0.017 (2) | 0.024 (2) | 0.033 (2) |
C8a | 0.049 (2) | 0.036 (2) | 0.052 (2) | 0.011 (2) | 0.020 (1) | 0.023 (2) |
C8b | 0.045 (2) | 0.040 (2) | 0.055 (2) | 0.012 (2) | 0.021 (2) | 0.026 (2) |
C9 | 0.041 (2) | 0.047 (2) | 0.064 (3) | 0.011 (2) | 0.017 (2) | 0.030 (2) |
C10 | 0.079 (3) | 0.062 (3) | 0.056 (2) | 0.015 (2) | 0.019 (2) | 0.027 (2) |
C11 | 0.044 (2) | 0.044 (2) | 0.059 (2) | 0.008 (2) | 0.019 (2) | 0.027 (2) |
C12 | 0.065 (3) | 0.055 (3) | 0.063 (2) | 0.015 (2) | 0.027 (2) | 0.034 (2) |
C13 | 0.084 (3) | 0.085 (3) | 0.063 (2) | 0.011 (2) | 0.029 (2) | 0.045 (3) |
C14 | 0.087 (4) | 0.087 (4) | 0.070 (3) | 0.011 (2) | 0.051 (3) | 0.027 (3) |
C15 | 0.066 (3) | 0.073 (3) | 0.080 (3) | 0.011 (2) | 0.042 (3) | 0.027 (2) |
C16 | 0.056 (2) | 0.056 (2) | 0.066 (2) | 0.011 (2) | 0.029 (2) | 0.027 (2) |
C17 | 0.052 (2) | 0.044 (2) | 0.046 (2) | 0.015 (2) | 0.020 (2) | 0.023 (2) |
C18 | 0.062 (2) | 0.051 (2) | 0.053 (2) | 0.020 (2) | 0.022 (2) | 0.023 (2) |
C19 | 0.081 (3) | 0.073 (3) | 0.070 (3) | 0.044 (2) | 0.030 (3) | 0.034 (3) |
C20 | 0.134 (3) | 0.063 (3) | 0.078 (3) | 0.052 (3) | 0.053 (3) | 0.043 (3) |
C21 | 0.112 (3) | 0.057 (3) | 0.093 (3) | 0.025 (2) | 0.056 (3) | 0.045 (2) |
C22 | 0.072 (2) | 0.054 (3) | 0.086 (3) | 0.018 (2) | 0.039 (2) | 0.042 (2) |
Geometric parameters (Å, º) top
O4—C3a | 1.407 (5) | C10—H3B | 0.99 |
O4—C4a | 1.386 (4) | C10—H3C | 1.00 |
N2—C1 | 1.389 (4) | C11—C12 | 1.402 (6) |
N2—C3 | 1.403 (6) | C11—C16 | 1.406 (5) |
N2—C9 | 1.453 (5) | C12—C13 | 1.384 (6) |
C1—C8b | 1.385 (6) | C12—H12 | 1.01 |
C1—C11 | 1.466 (6) | C13—C14 | 1.379 (7) |
C3—C3a | 1.353 (5) | C13—H13 | 1.02 |
C3—C10 | 1.474 (5) | C14—C15 | 1.381 (7) |
C3a—C8b | 1.394 (5) | C14—H14 | 1.01 |
C4a—C5 | 1.402 (6) | C15—C16 | 1.386 (7) |
C4a—C8a | 1.401 (6) | C15—H15 | 1.01 |
C5—C6 | 1.383 (5) | C16—H16 | 1.00 |
C5—H5 | 1.03 | C17—C18 | 1.379 (5) |
C6—C7 | 1.389 (7) | C17—C22 | 1.387 (6) |
C6—H6 | 0.98 | C18—C19 | 1.392 (6) |
C7—C8 | 1.386 (6) | C18—H18 | 1.01 |
C7—H7 | 1.00 | C19—C20 | 1.367 (7) |
C8—C8a | 1.377 (4) | C19—H19 | 1.01 |
C8—H8 | 1.02 | C20—C21 | 1.364 (7) |
C8a—C8b | 1.473 (5) | C20—H20 | 1.00 |
C9—C17 | 1.520 (6) | C21—C22 | 1.392 (6) |
C9—H9A | 0.99 | C21—H21 | 0.98 |
C9—H9B | 1.01 | C22—H10 | 0.96 |
C10—H3A | 0.97 | | |
| | | |
O4···C12i | 3.222 (4) | C15···C16iii | 3.489 (5) |
C8···C19ii | 3.526 (5) | C19···C19iv | 3.388 (8) |
C14···C16iii | 3.524 (6) | | |
| | | |
C3a—O4—C4a | 103.2 (3) | C3—C10—H3B | 115.4 |
C1—N2—C3 | 111.8 (3) | C3—C10—H3C | 114.4 |
C1—N2—C9 | 126.4 (3) | H3A—C10—H3B | 104.3 |
C3—N2—C9 | 121.7 (3) | H3A—C10—H3C | 103.2 |
N2—C1—C8b | 105.3 (3) | H3B—C10—H3C | 102.1 |
N2—C1—C11 | 125.4 (3) | C1—C11—C12 | 117.9 (3) |
C8b—C1—C11 | 129.3 (3) | C1—C11—C16 | 124.8 (4) |
N2—C3—C3a | 103.6 (3) | C12—C11—C16 | 117.3 (4) |
N2—C3—C10 | 124.6 (3) | C11—C12—C13 | 121.2 (4) |
C3a—C3—C10 | 131.7 (4) | C11—C12—H12 | 119.0 |
O4—C3a—C3 | 135.1 (4) | C13—C12—H12 | 119.7 |
O4—C3a—C8b | 113.0 (3) | C12—C13—C14 | 120.2 (4) |
C3—C3a—C8b | 111.9 (4) | C12—C13—H13 | 119.4 |
O4—C4a—C5 | 123.2 (4) | C14—C13—H13 | 120.3 |
O4—C4a—C8a | 114.1 (3) | C13—C14—C15 | 120.1 (5) |
C5—C4a—C8a | 122.7 (3) | C13—C14—H14 | 119.0 |
C4a—C5—C6 | 116.6 (4) | C15—C14—H14 | 120.8 |
C4a—C5—H5 | 123.3 | C14—C15—C16 | 120.0 (4) |
C6—C5—H5 | 120.0 | C14—C15—H15 | 121.0 |
C5—C6—C7 | 120.9 (4) | C16—C15—H15 | 119.1 |
C5—C6—H6 | 120.0 | C11—C16—C15 | 121.2 (4) |
C7—C6—H6 | 119.2 | C11—C16—H16 | 119.7 |
C6—C7—C8 | 122.0 (3) | C15—C16—H16 | 119.0 |
C6—C7—H7 | 118.4 | C9—C17—C18 | 118.9 (3) |
C8—C7—H7 | 119.6 | C9—C17—C22 | 121.8 (3) |
C7—C8—C8a | 118.5 (4) | C18—C17—C22 | 119.3 (4) |
C7—C8—H8 | 120.2 | C17—C18—C19 | 120.5 (4) |
C8a—C8—H8 | 121.3 | C17—C18—H18 | 120.6 |
C4a—C8a—C8 | 119.2 (4) | C19—C18—H18 | 118.9 |
C4a—C8a—C8b | 104.2 (3) | C18—C19—C20 | 119.7 (4) |
C8—C8a—C8b | 136.5 (4) | C18—C19—H19 | 119.2 |
C1—C8b—C3a | 107.3 (3) | C20—C19—H19 | 121.1 |
C1—C8b—C8a | 147.2 (3) | C19—C20—C21 | 120.3 (5) |
C3a—C8b—C8a | 105.5 (4) | C19—C20—H20 | 118.1 |
N2—C9—C17 | 114.0 (3) | C21—C20—H20 | 121.6 |
N2—C9—H9A | 111.3 | C20—C21—C22 | 120.8 (4) |
N2—C9—H9B | 111.5 | C20—C21—H21 | 117.7 |
C17—C9—H9A | 109.4 | C22—C21—H21 | 121.5 |
C17—C9—H9B | 108.0 | C17—C22—C21 | 119.3 (4) |
H9A—C9—H9B | 102.0 | C17—C22—H10 | 121.7 |
C3—C10—H3A | 115.6 | C21—C22—H10 | 118.9 |
| | | |
O4—C3a—C3—N2 | −179.7 (4) | C3a—C8b—C8a—C8 | −177.6 (5) |
O4—C3a—C3—C10 | −2.2 (8) | C4a—O4—C3a—C8b | −0.3 (4) |
O4—C3a—C8b—C1 | −179.8 (3) | C4a—C5—C6—C7 | 0.4 (6) |
O4—C3a—C8b—C8a | −0.2 (4) | C4a—C8a—C8—C7 | 0.4 (6) |
O4—C4a—C5—C6 | −178.1 (4) | C5—C4a—C8a—C8 | −2.1 (6) |
O4—C4a—C8a—C8 | 177.7 (3) | C5—C4a—C8a—C8b | 179.2 (4) |
O4—C4a—C8a—C8b | −1.0 (4) | C5—C6—C7—C8 | −2.1 (7) |
N2—C1—C8b—C3a | −0.7 (4) | C6—C5—C4a—C8a | 1.8 (6) |
N2—C1—C8b—C8a | −180.0 (6) | C6—C7—C8—C8a | 1.7 (6) |
N2—C1—C11—C12 | −142.6 (4) | C7—C8—C8a—C8b | 178.5 (4) |
N2—C1—C11—C16 | 40.6 (6) | C8a—C8b—C1—C11 | 2.4 (9) |
N2—C3—C3a—C8b | −0.3 (4) | C8b—C1—N2—C9 | 179.2 (3) |
N2—C9—C17—C18 | −173.7 (3) | C8b—C1—C11—C12 | 34.6 (6) |
N2—C9—C17—C22 | 6.7 (5) | C8b—C1—C11—C16 | −142.2 (4) |
C1—N2—C3—C3a | −0.1 (4) | C8b—C3a—C3—C10 | 177.2 (4) |
C1—N2—C3—C10 | −177.9 (4) | C9—N2—C1—C11 | −3.0 (6) |
C1—N2—C9—C17 | −96.7 (5) | C9—N2—C3—C10 | 3.4 (6) |
C1—C8b—C3a—C3 | 0.7 (5) | C9—C17—C18—C19 | −179.9 (3) |
C1—C8b—C8a—C4a | 180.0 (6) | C9—C17—C22—C21 | −179.7 (4) |
C1—C8b—C8a—C8 | 2 (1) | C11—C12—C13—C14 | −1.1 (6) |
C1—C11—C12—C13 | −176.9 (3) | C11—C16—C15—C14 | −1.5 (6) |
C1—C11—C16—C15 | 177.9 (3) | C12—C11—C16—C15 | 1.2 (5) |
C3—N2—C1—C8b | 0.5 (4) | C12—C13—C14—C15 | 0.8 (7) |
C3—N2—C1—C11 | 178.3 (4) | C13—C12—C11—C16 | 0.2 (5) |
C3—N2—C9—C17 | 81.9 (4) | C13—C14—C15—C16 | 0.5 (6) |
C3—C3a—O4—C4a | 179.0 (5) | C17—C18—C19—C20 | −0.7 (6) |
C3—C3a—C8b—C8a | −179.7 (3) | C17—C22—C21—C20 | −0.1 (7) |
C3a—O4—C4a—C5 | −179.3 (4) | C18—C17—C22—C21 | 0.7 (6) |
C3a—O4—C4a—C8a | 0.8 (4) | C18—C19—C20—C21 | 1.2 (7) |
C3a—C3—N2—C9 | −178.9 (3) | C19—C18—C17—C22 | −0.3 (6) |
C3a—C8b—C1—C11 | −178.3 (4) | C19—C20—C21—C22 | −0.8 (7) |
C3a—C8b—C8a—C4a | 0.7 (4) | | |
Symmetry codes: (i) −x, −y+1, −z; (ii) x−1, y, z−1; (iii) −x, −y, −z−1; (iv) −x+1, −y, −z. |
Crystal data top
C24H19NO | Z = 2 |
Mr = 337.42 | F(000) = 356.00 |
Triclinic, P1 | Dx = 1.287 Mg m−3 |
a = 9.956 (1) Å | Mo Kα radiation, λ = 0.7107 Å |
b = 11.329 (2) Å | Cell parameters from 24 reflections |
c = 8.939 (2) Å | θ = 10.6–17.1° |
α = 109.89 (1)° | µ = 0.08 mm−1 |
β = 107.06 (1)° | T = 296 K |
γ = 69.47 (1)° | Prism, light brown |
V = 870.3 (3) Å3 | 0.4 × 0.4 × 0.3 mm |
Data collection top
Rigaku AFC-6S diffractometer | 1789 reflections with I > 3σ(I) |
Radiation source: X-ray tube | Rint = 0.018 |
Graphite monochromator | θmax = 27.5°, θmin = 2.0° |
ω/2θ scans | h = 0→12 |
Absorption correction: ψ scan (North et al., 1968) | k = −13→14 |
Tmin = 0.987, Tmax = 1.000 | l = −11→11 |
4223 measured reflections | 3 standard reflections every 150 reflections |
3991 independent reflections | intensity decay: −1.4% |
Refinement top
Refinement on F | 0 constraints |
Least-squares matrix: full | H-atom parameters not refined |
R[F2 > 2σ(F2)] = 0.045 | Weighting scheme based on measured s.u.'s w = 1/[σ2(Fo)] |
wR(F2) = 0.197 | (Δ/σ)max = 0.050 |
S = 1.04 | Δρmax = 0.24 e Å−3 |
3991 reflections | Δρmin = −0.23 e Å−3 |
236 parameters | Extinction correction: Zachariasen (1967), equ (3) [Zachariasen, W. H. (1968). Acta Cryst. A24, p213.] |
0 restraints | Extinction coefficient: 2.06 (7) × 10-6 |
Crystal data top
C24H19NO | γ = 69.47 (1)° |
Mr = 337.42 | V = 870.3 (3) Å3 |
Triclinic, P1 | Z = 2 |
a = 9.956 (1) Å | Mo Kα radiation |
b = 11.329 (2) Å | µ = 0.08 mm−1 |
c = 8.939 (2) Å | T = 296 K |
α = 109.89 (1)° | 0.4 × 0.4 × 0.3 mm |
β = 107.06 (1)° | |
Data collection top
Rigaku AFC-6S diffractometer | 1789 reflections with I > 3σ(I) |
Absorption correction: ψ scan (North et al., 1968) | Rint = 0.018 |
Tmin = 0.987, Tmax = 1.000 | 3 standard reflections every 150 reflections |
4223 measured reflections | intensity decay: −1.4% |
3991 independent reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.045 | 0 restraints |
wR(F2) = 0.197 | H-atom parameters not refined |
S = 1.04 | Δρmax = 0.24 e Å−3 |
3991 reflections | Δρmin = −0.23 e Å−3 |
236 parameters | |
Special details top
Experimental. The scan width was (1.68 + 0.34tanθ)° with an ω scan speed of 8° per minute
[up to 5 scans to achieve I/σ(I) > 10]. Stationary background counts were
recorded at each end of the scan, and the scan time:background time ratio was
2:1. |
Refinement. The final cycle of full-matrix least-squares refinement (SHELXL93:
Σw(Fo2-Fc2)2, where w = 1/[Σ2(Fo2) + (0.1P)2] and P =
[Max(Fo2,0) + 2Fc2)/3], was based on 1420 (I) or 1789 (II) observed
reflections and 236 (I) or 236 (II) variable parameters and converged [largest
parameter shift was 0.07 (I) or 0.00 (II) times its esd] with unweighted and
weighted agreement factors of: R1 = Σ||Fo| - |Fc||/Σ|Fo| = 0.049 (I),
0.045 (II); wR2 = [Σ(w(Fo2-Fc2)2)/Σw(Fo2)2]1/2 = 0.225(I),
0.197(II). The standard deviation of an observation of unit weight
([Σw(Fo2-Fc2)2/(No-Nv)]1/2, where No = number of observations and Nv =
number of variables) was 1.03 (I) or 1.04 (II). The weighting scheme was based
on counting statistics and included a factor [p = 0.010 (I) or 0.002 (II)] to
downweight the intense reflections. The maximum and minimum peaks on the final
difference Fourier map corresponded to 0.25 (I) and 0.24 (II), and -0.22 (I)
and -0.23 (II) eÅ-3, respectively.
Neutral atom scattering factors were taken from Cromer & Waber (1974).
Anomalous dispersion effects were included in Fcalc
(Ibers & Hamilton, 1964); the values for δf' and δf'' were those
of Creagh & McAuley (1992). The values for the mass attenuation coefficients
are those of Creagh & Hubbell (1992). |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
O4 | 0.6976 (2) | 0.2718 (2) | 0.9049 (2) | 0.0479 (7) | |
N2 | 0.3141 (2) | 0.3291 (2) | 0.8599 (3) | 0.0423 (8) | |
C1 | 0.3604 (3) | 0.3780 (2) | 1.0247 (3) | 0.045 (1) | |
C3 | 0.4312 (3) | 0.2770 (2) | 0.7770 (3) | 0.0407 (9) | |
C3a | 0.5486 (3) | 0.2980 (2) | 0.8976 (3) | 0.0422 (9) | |
C4a | 0.7531 (3) | 0.3177 (3) | 1.0691 (3) | 0.045 (1) | |
C5 | 0.9000 (3) | 0.3083 (3) | 1.1313 (4) | 0.051 (1) | |
C6 | 0.9387 (3) | 0.3589 (3) | 1.2978 (4) | 0.056 (1) | |
C7 | 0.8335 (3) | 0.4155 (3) | 1.3947 (3) | 0.058 (1) | |
C8 | 0.6875 (3) | 0.4226 (3) | 1.3300 (3) | 0.053 (1) | |
C8a | 0.6448 (3) | 0.3725 (2) | 1.1644 (3) | 0.0432 (9) | |
C8b | 0.5098 (3) | 0.3581 (2) | 1.0497 (3) | 0.0435 (9) | |
C9 | 0.1633 (3) | 0.3304 (3) | 0.7836 (3) | 0.0453 (9) | |
C10 | 0.2604 (3) | 0.4394 (3) | 1.1410 (3) | 0.060 (1) | |
C11 | 0.4257 (3) | 0.2202 (2) | 0.6021 (3) | 0.0407 (9) | |
C12 | 0.3354 (3) | 0.1421 (3) | 0.5005 (3) | 0.051 (1) | |
C13 | 0.3443 (3) | 0.0852 (3) | 0.3386 (4) | 0.060 (1) | |
C14 | 0.4452 (4) | 0.1024 (3) | 0.2756 (3) | 0.063 (1) | |
C15 | 0.5366 (3) | 0.1773 (3) | 0.3735 (4) | 0.061 (1) | |
C16 | 0.5265 (3) | 0.2369 (3) | 0.5351 (3) | 0.052 (1) | |
C17 | 0.1214 (3) | 0.2129 (2) | 0.7814 (3) | 0.0392 (9) | |
C18 | 0.2114 (3) | 0.1256 (3) | 0.8706 (3) | 0.054 (1) | |
C19 | 0.1681 (3) | 0.0206 (3) | 0.8663 (4) | 0.062 (1) | |
C20 | 0.0374 (4) | 0.0015 (3) | 0.7747 (4) | 0.064 (1) | |
C21 | −0.0524 (3) | 0.0876 (3) | 0.6851 (4) | 0.062 (1) | |
C22 | −0.0108 (3) | 0.1928 (3) | 0.6889 (3) | 0.051 (1) | |
H5 | 0.9786 | 0.2687 | 1.0642 | 0.066* | |
H6 | 1.0452 | 0.3539 | 1.3489 | 0.066* | |
H7 | 0.8716 | 0.4500 | 1.5126 | 0.070* | |
H8 | 0.6221 | 0.4608 | 1.4068 | 0.066* | |
H9A | 0.0935 | 0.4116 | 0.8356 | 0.052* | |
H9B | 0.1413 | 0.3374 | 0.6702 | 0.052* | |
H10A | 0.1636 | 0.4185 | 1.1001 | 0.068* | |
H10B | 0.2961 | 0.4185 | 1.2445 | 0.068* | |
H10C | 0.2282 | 0.5370 | 1.1702 | 0.068* | |
H12 | 0.2586 | 0.1277 | 0.5420 | 0.061* | |
H13 | 0.2767 | 0.0306 | 0.2664 | 0.068* | |
H14 | 0.4499 | 0.0595 | 0.1609 | 0.073* | |
H15 | 0.6082 | 0.1930 | 0.3279 | 0.068* | |
H16 | 0.5944 | 0.2909 | 0.6047 | 0.054* | |
H18 | 0.3044 | 0.1373 | 0.9329 | 0.058* | |
H19 | 0.2280 | −0.0409 | 0.9316 | 0.067* | |
H20 | 0.0046 | −0.0730 | 0.7718 | 0.065* | |
H21 | −0.1444 | 0.0730 | 0.6127 | 0.066* | |
H22 | −0.0776 | 0.2546 | 0.6216 | 0.053* | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
O4 | 0.041 (1) | 0.055 (1) | 0.048 (1) | −0.018 (1) | 0.010 (1) | 0.009 (1) |
N2 | 0.040 (2) | 0.042 (2) | 0.048 (2) | −0.016 (1) | 0.009 (1) | 0.011 (1) |
C1 | 0.049 (2) | 0.040 (2) | 0.051 (2) | −0.016 (2) | 0.017 (2) | 0.008 (2) |
C3 | 0.041 (2) | 0.037 (2) | 0.048 (2) | −0.015 (1) | 0.009 (2) | 0.011 (1) |
C3a | 0.040 (2) | 0.042 (2) | 0.048 (2) | −0.016 (1) | 0.012 (2) | 0.008 (1) |
C4a | 0.054 (2) | 0.039 (2) | 0.043 (2) | −0.020 (2) | 0.005 (2) | 0.011 (1) |
C5 | 0.048 (2) | 0.047 (2) | 0.063 (2) | −0.021 (2) | 0.006 (2) | 0.016 (2) |
C6 | 0.055 (2) | 0.048 (2) | 0.065 (2) | −0.026 (2) | −0.010 (2) | 0.023 (2) |
C7 | 0.075 (2) | 0.052 (2) | 0.048 (2) | −0.033 (2) | −0.005 (2) | 0.014 (2) |
C8 | 0.072 (3) | 0.042 (2) | 0.050 (2) | −0.023 (2) | 0.012 (2) | 0.009 (2) |
C8a | 0.052 (2) | 0.036 (2) | 0.045 (2) | −0.018 (2) | 0.007 (2) | 0.011 (1) |
C8b | 0.050 (2) | 0.040 (2) | 0.045 (2) | −0.019 (1) | 0.012 (2) | 0.008 (1) |
C9 | 0.039 (2) | 0.041 (2) | 0.059 (2) | −0.011 (1) | 0.007 (2) | 0.020 (2) |
C10 | 0.061 (2) | 0.065 (2) | 0.059 (2) | −0.019 (2) | 0.027 (2) | 0.006 (2) |
C11 | 0.044 (2) | 0.038 (2) | 0.043 (2) | −0.011 (1) | 0.008 (1) | 0.015 (1) |
C12 | 0.052 (2) | 0.060 (2) | 0.046 (2) | −0.024 (2) | 0.009 (2) | 0.012 (2) |
C13 | 0.057 (2) | 0.069 (2) | 0.049 (2) | −0.023 (2) | 0.002 (2) | 0.010 (2) |
C14 | 0.073 (3) | 0.073 (2) | 0.041 (2) | −0.019 (2) | 0.009 (2) | 0.018 (2) |
C15 | 0.074 (3) | 0.066 (2) | 0.058 (2) | −0.020 (2) | 0.024 (2) | 0.023 (2) |
C16 | 0.059 (2) | 0.050 (2) | 0.055 (2) | −0.023 (2) | 0.014 (2) | 0.013 (2) |
C17 | 0.038 (2) | 0.038 (2) | 0.044 (2) | −0.010 (1) | 0.013 (1) | 0.009 (1) |
C18 | 0.047 (2) | 0.050 (2) | 0.067 (2) | −0.015 (2) | 0.003 (2) | 0.022 (2) |
C19 | 0.072 (3) | 0.050 (2) | 0.073 (2) | −0.016 (2) | 0.010 (2) | 0.030 (2) |
C20 | 0.079 (3) | 0.048 (2) | 0.078 (2) | −0.032 (2) | 0.023 (2) | 0.010 (2) |
C21 | 0.056 (2) | 0.062 (2) | 0.073 (2) | −0.031 (2) | 0.006 (2) | 0.014 (2) |
C22 | 0.043 (2) | 0.052 (2) | 0.057 (2) | −0.015 (2) | 0.004 (2) | 0.017 (2) |
Geometric parameters (Å, º) top
O4—C3a | 1.392 (4) | C10—H10A | 0.97 |
O4—C4a | 1.392 (3) | C10—H10B | 1.00 |
N2—C1 | 1.384 (3) | C11—C12 | 1.396 (4) |
N2—C3 | 1.408 (4) | C11—C16 | 1.402 (5) |
N2—C9 | 1.452 (3) | C12—C13 | 1.384 (4) |
C1—C8b | 1.385 (4) | C12—H12 | 1.02 |
C1—C10 | 1.478 (4) | C13—C14 | 1.381 (6) |
C3a—C3 | 1.366 (4) | C13—H13 | 1.01 |
C3a—C8b | 1.398 (4) | C14—C15 | 1.372 (5) |
C3—C11 | 1.467 (4) | C14—H14 | 0.98 |
C4a—C5 | 1.384 (4) | C15—C16 | 1.388 (4) |
C4a—C8a | 1.407 (4) | C15—H15 | 1.01 |
C5—C6 | 1.389 (4) | C16—H16 | 1.00 |
C5—H5 | 1.01 | C17—C18 | 1.383 (4) |
C6—C7 | 1.392 (5) | C17—C22 | 1.383 (4) |
C6—H6 | 1.01 | C18—C19 | 1.386 (5) |
C7—C8 | 1.382 (5) | C18—H18 | 0.96 |
C7—H7 | 1.00 | C19—C20 | 1.365 (4) |
C8a—C8 | 1.387 (4) | C19—H19 | 0.98 |
C8a—C8b | 1.454 (4) | C20—C21 | 1.375 (4) |
C8—H8 | 0.97 | C20—H20 | 1.00 |
C9—C17 | 1.521 (5) | C21—C22 | 1.380 (5) |
C9—H9A | 1.00 | C21—H21 | 0.99 |
C9—H9B | 1.00 | C22—H22 | 1.01 |
C10—H10C | 1.01 | | |
| | | |
O4···C21i | 3.293 (4) | C8b···C8bii | 3.544 (7) |
C1···C4aii | 3.542 (4) | C11···C13iii | 3.531 (4) |
C3···C8ii | 3.553 (4) | C12···C13iii | 3.597 (4) |
C6···C9ii | 3.571 (5) | C21···C21iv | 3.476 (6) |
| | | |
C3a—O4—C4a | 103.7 (2) | C1—C10—H10A | 116.6 |
C1—N2—C3 | 111.6 (2) | C1—C10—H10B | 114.7 |
C1—N2—C9 | 123.7 (2) | H10C—C10—H10A | 103.6 |
C3—N2—C9 | 124.7 (2) | H10C—C10—H10B | 101.3 |
N2—C1—C8b | 106.4 (3) | H10A—C10—H10B | 104.2 |
N2—C1—C10 | 123.3 (2) | C3—C11—C12 | 124.6 (3) |
C8b—C1—C10 | 130.3 (2) | C3—C11—C16 | 117.5 (3) |
O4—C3a—C3 | 135.1 (3) | C12—C11—C16 | 117.7 (3) |
O4—C3a—C8b | 112.8 (2) | C11—C12—C13 | 120.8 (3) |
C3—C3a—C8b | 112.1 (3) | C11—C12—H12 | 121.2 |
N2—C3—C3a | 103.3 (2) | C13—C12—H12 | 118.0 |
N2—C3—C11 | 127.9 (2) | C12—C13—C14 | 120.5 (3) |
C3a—C3—C11 | 128.8 (3) | C12—C13—H13 | 119.7 |
O4—C4a—C5 | 123.0 (3) | C14—C13—H13 | 119.8 |
O4—C4a—C8a | 113.0 (2) | C13—C14—C15 | 119.9 (3) |
C5—C4a—C8a | 123.9 (2) | C13—C14—H14 | 118.5 |
C4a—C5—C6 | 116.3 (3) | C15—C14—H14 | 121.6 |
C4a—C5—H5 | 124.6 | C14—C15—C16 | 120.0 (4) |
C6—C5—H5 | 119.1 | C14—C15—H15 | 120.6 |
C5—C6—C7 | 121.0 (3) | C16—C15—H15 | 119.4 |
C5—C6—H6 | 119.1 | C11—C16—C15 | 121.1 (3) |
C7—C6—H6 | 119.9 | C11—C16—H16 | 120.0 |
C6—C7—C8 | 121.7 (3) | C15—C16—H16 | 118.9 |
C6—C7—H7 | 115.1 | C9—C17—C18 | 121.9 (2) |
C8—C7—H7 | 123.2 | C9—C17—C22 | 119.4 (2) |
C4a—C8a—C8 | 118.0 (3) | C18—C17—C22 | 118.7 (3) |
C4a—C8a—C8b | 104.7 (2) | C17—C18—C19 | 119.9 (3) |
C8—C8a—C8b | 137.3 (3) | C17—C18—H18 | 119.4 |
C7—C8—C8a | 119.1 (3) | C19—C18—H18 | 120.6 |
C7—C8—H8 | 116.3 | C18—C19—C20 | 120.9 (3) |
C8a—C8—H8 | 124.6 | C18—C19—H19 | 121.7 |
C1—C8b—C3a | 106.6 (2) | C20—C19—H19 | 117.4 |
C1—C8b—C8a | 147.7 (3) | C19—C20—C21 | 119.5 (4) |
C3a—C8b—C8a | 105.7 (3) | C19—C20—H20 | 121.6 |
N2—C9—C17 | 114.5 (2) | C21—C20—H20 | 118.9 |
N2—C9—H9A | 111.4 | C20—C21—C22 | 120.1 (3) |
N2—C9—H9B | 110.7 | C20—C21—H21 | 121.1 |
C17—C9—H9A | 108.6 | C22—C21—H21 | 118.7 |
C17—C9—H9B | 108.8 | C17—C22—C21 | 120.8 (3) |
H9A—C9—H9B | 102.1 | C17—C22—H22 | 120.1 |
C1—C10—H10C | 114.6 | C21—C22—H22 | 119.1 |
| | | |
O4—C3a—C3—N2 | 179.7 (3) | C3—C3a—C8b—C8a | 179.4 (3) |
O4—C3a—C3—C11 | −3.1 (6) | C3—C11—C12—C13 | −175.6 (2) |
O4—C3a—C8b—C1 | −179.8 (3) | C3—C11—C16—C15 | 174.7 (2) |
O4—C3a—C8b—C8a | 0.4 (3) | C4a—O4—C3a—C8b | 0.1 (3) |
O4—C4a—C5—C6 | 179.8 (3) | C4a—C5—C6—C7 | 0.1 (5) |
O4—C4a—C8a—C8 | −179.4 (3) | C4a—C8a—C8—C7 | −0.7 (5) |
O4—C4a—C8a—C8b | 0.8 (3) | C5—C4a—C8a—C8 | 1.4 (5) |
N2—C1—C8b—C3a | 0.3 (3) | C5—C4a—C8a—C8b | −178.4 (3) |
N2—C1—C8b—C8a | 179.9 (5) | C5—C6—C7—C8 | 0.5 (5) |
N2—C3—C3a—C8b | 1.0 (3) | C6—C5—C4a—C8a | −1.1 (5) |
N2—C3—C11—C12 | −38.1 (4) | C6—C7—C8—C8a | −0.2 (5) |
N2—C3—C11—C16 | 147.3 (3) | C7—C8—C8a—C8b | 179.0 (4) |
N2—C9—C17—C18 | 11.3 (4) | C8a—C8b—C1—C10 | 0.7 (8) |
N2—C9—C17—C22 | −169.3 (2) | C8b—C1—N2—C9 | 179.5 (3) |
C1—N2—C3—C3a | −0.8 (3) | C8b—C3a—C3—C11 | 178.2 (3) |
C1—N2—C3—C11 | −178.0 (3) | C9—N2—C1—C10 | −1.2 (5) |
C1—N2—C9—C17 | −87.0 (3) | C9—N2—C3—C11 | 2.8 (5) |
C1—C8b—C3a—C3 | −0.8 (4) | C9—C17—C18—C19 | 179.3 (3) |
C1—C8b—C8a—C4a | 179.7 (5) | C9—C17—C22—C21 | −179.6 (3) |
C1—C8b—C8a—C8 | −0.0 (8) | C11—C12—C13—C14 | 1.5 (4) |
C3a—O4—C4a—C5 | 178.7 (3) | C11—C16—C15—C14 | 1.2 (4) |
C3a—O4—C4a—C8a | −0.6 (3) | C12—C11—C16—C15 | −0.3 (4) |
C3a—C3—N2—C9 | 180.0 (3) | C12—C13—C14—C15 | −0.6 (4) |
C3a—C3—C11—C12 | 145.3 (3) | C13—C12—C11—C16 | −1.0 (4) |
C3a—C3—C11—C16 | −29.3 (4) | C13—C14—C15—C16 | −0.7 (4) |
C3a—C8b—C1—C10 | −178.9 (3) | C17—C18—C19—C20 | 0.1 (5) |
C3a—C8b—C8a—C4a | −0.7 (3) | C17—C22—C21—C20 | 0.4 (4) |
C3a—C8b—C8a—C8 | 179.6 (4) | C18—C17—C22—C21 | −0.1 (4) |
C3—N2—C1—C8b | 0.3 (3) | C18—C19—C20—C21 | 0.2 (5) |
C3—N2—C1—C10 | 179.6 (3) | C19—C18—C17—C22 | −0.1 (4) |
C3—N2—C9—C17 | 92.2 (3) | C19—C20—C21—C22 | −0.4 (5) |
C3—C3a—O4—C4a | −178.6 (4) | | |
Symmetry codes: (i) x+1, y, z; (ii) −x+1, −y+1, −z+2; (iii) −x+1, −y, −z+1; (iv) −x, −y, −z+1. |
Experimental details
| (I) | (II) |
Crystal data |
Chemical formula | C24H19NO | C24H19NO |
Mr | 337.42 | 337.42 |
Crystal system, space group | Triclinic, P1 | Triclinic, P1 |
Temperature (K) | 296 | 296 |
a, b, c (Å) | 10.405 (2), 11.524 (2), 9.177 (2) | 9.956 (1), 11.329 (2), 8.939 (2) |
α, β, γ (°) | 113.44 (1), 113.94 (2), 93.94 (2) | 109.89 (1), 107.06 (1), 69.47 (1) |
V (Å3) | 887.4 (4) | 870.3 (3) |
Z | 2 | 2 |
Radiation type | Mo Kα | Mo Kα |
µ (mm−1) | 0.08 | 0.08 |
Crystal size (mm) | 0.4 × 0.3 × 0.2 | 0.4 × 0.4 × 0.3 |
|
Data collection |
Diffractometer | Rigaku AFC-6S diffractometer | Rigaku AFC-6S diffractometer |
Absorption correction | – | ψ scan (North et al., 1968) |
Tmin, Tmax | – | 0.987, 1.000 |
No. of measured, independent and observed [I > 3σ(I)] reflections | 4289, 4067, 1420 | 4223, 3991, 1789 |
Rint | 0.020 | 0.018 |
(sin θ/λ)max (Å−1) | 0.650 | 0.649 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.049, 0.225, 1.03 | 0.045, 0.197, 1.04 |
No. of reflections | 4067 | 3991 |
No. of parameters | 236 | 236 |
H-atom treatment | H-atom parameters not refined | H-atom parameters not refined |
Δρmax, Δρmin (e Å−3) | 0.26, −0.22 | 0.24, −0.23 |
Fused heterocycles such as the title compounds, 2-benzyl-3-methyl-1-phenylbenzo[b]furo[2,3-c]pyrrole, (I), and 2-benzyl-1-methyl-3-phenylbenzo[b]furo[2,3-c]pyrrole, (II), are of great importance in the construction of more complex molecules, for example, by cycloaddition chemistry. In connection with our recent studies of these fused heterocycles, obtained by the reaction of mesoionic münchnones (1,3-oxazolium-5-olates) with 2-nitrobenzo[b]furan (Gribble et al., 1998), we needed to differentiate the two isomeric compounds, (I) and (II). The crystal structure determinations reported in the present paper support our isomer assignments reached using NMR techniques (Gribble et al., 1999). The only previous example of the benzo[b]furo[2,3-c]pyrrole ring system was reported by Sha et al. (1995), but a crystal structure was not described. \scheme
The tricyclic fused benzofuropyrrole ring system in both (I) and (II) is planar, as expected. The C1 phenyl ring in (I) is twisted 37.3 (2)°? out of planarity, while the corresponding C3 phenyl ring in (II) is twisted by 33.7 (1)°?, consistent with the greater interaction of the C1 phenyl in (I) with H8. The N-benzyl phenyl rings in (I) and (II) are twisted 85.5 (1)? and 82.5 (1)°? out of the plane of the benzofuropyrrole ring system, respectively. This is anticipated, since π-conjugation between these aromatic systems is not possible.
The unequal pyrrole C=C double bonds in (I) [C1—C8b 1.385 (6) Å and C3—C3a 1.353 (5) Å] and (II) [C1—C8b 1.385 (4) Å and C3—C3a 1.366 (4) Å] presumably reflect differing degrees of π-conjugation. For example, the larger C3—C3a bond length in (II) may be a consequence of π-conjugation in the benzofuran. Steric interaction on the C1—C8b bond, due to the phenyl ring in (I) or the methyl group in (II), appears minimal as the bond lengths are nearly identical [1.385 (6) in (I), 1.385 (4) Å in (II)]. By comparison, N-methylpyrrole itself has a C=C double bond length of 1.35 Å and a C3—C4 bond length of 1.43 Å (electron diffraction; Vilkov et al., 1962). On the other hand, N-benzylisoindole, which is a delocalized system like naphthalene, has an average pyrrole ring C=C double bond length of 1.384 Å (Bonnett et al., 1985).
That pyrrole ring distortion is present in both (I) and (II) is evident from several bond angles. Thus, in (I) and (II) the C1—C8b—C8a bond angles are 147.2 (3)° and 147.7 (3)°, respectively, while the C3—C3a—O4 bond angles are 135.1 (4)° and 135.1 (3)°, respectively. The comparable bond angle in pyrrole itself (C2—C3—H3) is 126° (Vilkov et al., 1962). Likewise, as a consequence of the two fused five-membered rings, the central C3a—C8b bond is very short for a C—C single bond in (I) and (II), at 1.394 (5) and 1.398 (4) Å, respectively. In N-methylpyrrole, the C3—C4 bond length is 1.43 Å (Vilkov et al., 1962), and this single bond length in N-benzylisoindole is 1.429 Å (Bonnett et al., 1985). The C1—N2 and N2—C3 bond lengths in (I) and (II) are 1.389 (4) and 1.403 (6) Å, respectively, for (I) and 1.384 (3) and 1.408 (4) Å, respectively, for (II). These compare with the corresponding bond lengths in N-methylpyrrole (1.40 Å; Vilkov et al., 1962) and N-benzylisoindole (1.362 Å; Bonnett et al., 1985). The mean deviation of the pyrrole nitrogen N2 from the plane of its nearest three neighbours, C1, C3 and C9, is -0.0095 Å in (I) and -0.0056 Å in (II). The internal bond angles in the pyrrole rings of (I) and (II) are quite similar to those found in N-benzylisoindole. For example, the C1—N2—C3 bond angles in (I) and (II) are 111.8 (3) and 111.6 (2)°, respectively. In N-benzylisoindole this angle is 111° (Bonnett et al., 1985). Likewise, the other internal pyrrole ring bond angles in (I) and (II) do not deviate much from those reported for N-benzylpyrrole. The least squares planes mean deviation for the benzofuropyrrole ring is 0.0134 in (I) and 0.0086 Å in (II).
In summary, the pyrrole rings in (I) and (II), which compounds are reactive as dienes in Diels-Alder reactions, although somewhat strained due to being fused to another five-membered ring, do not differ appreciably from that in N-methylpyrrole, except for a relatively short C—C single bond (C3a—C8b) in the pyrrole ring.