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ISSN: 2056-9890

tert-Butyl 2-borono-1H-pyrrole-1-carboxyl­ate

aDepartment of Chemistry, Fudan University, 220 Handan Road, Shanghai, 200433, People's Republic of China
*Correspondence e-mail: wangbing@fudan.edu.cn

(Received 16 February 2009; accepted 28 February 2009; online 6 March 2009)

In the crystal structure of the title compound, C9H14BNO4, the boronic acid group and carbamate groups are nearly co-planar with the pyrrole ring, making dihedral angles of 0.1 (2) and 2.2 (2)°, respectively. Intra­molecular and inter­molecular O—H⋯O hydrogen bonds help to stabilize the structure, the latter interaction leading to inversion dimers..

Related literature

For general background, see: Hall (2005[Hall, D. G. (2005). Editor. Boronic Acids, Weinheim: Wiley-VCH.]); Kelly & Fuchs (1993[Kelly, T. A. & Fuchs, V. U. (1993). Tetrahedron 49, 1009-1016.]).

[Scheme 1]

Experimental

Crystal data
  • C9H14BNO4

  • Mr = 211.02

  • Orthorhombic, P b c a

  • a = 13.014 (3) Å

  • b = 9.940 (2) Å

  • c = 17.417 (4) Å

  • V = 2252.9 (9) Å3

  • Z = 8

  • Mo Kα radiation

  • μ = 0.10 mm−1

  • T = 293 K

  • 0.25 × 0.12 × 0.10 mm

Data collection
  • Bruker SMART 1000 CCD area-detector diffractometer

  • Absorption correction: none

  • 9542 measured reflections

  • 2213 independent reflections

  • 1208 reflections with I > 2σ(I)

  • Rint = 0.065

Refinement
  • R[F2 > 2σ(F2)] = 0.042

  • wR(F2) = 0.106

  • S = 0.85

  • 2213 reflections

  • 192 parameters

  • All H-atom parameters refined

  • Δρmax = 0.12 e Å−3

  • Δρmin = −0.21 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
O3—H3A⋯O2 0.87 (2) 1.73 (2) 2.5819 (18) 164.7 (18)
O4—H4⋯O3i 0.89 (3) 1.88 (3) 2.769 (3) 173 (3)
Symmetry code: (i) -x+2, -y+1, -z+1.

Data collection: SMART (Bruker, 2001[Bruker (2001). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2001[Bruker (2001). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXTL (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL.

Supporting information


Comment top

Boronic acids are versatile compounds widely used in the synthesis of biaryls, as therapeutical agents, and as chemical sensors (Hall, 2005). The title compound is the key intermediate for the synthesis of (+)-pinanediol-L-boroproline (Kelly & Fuchs, 1993).

In the molecular structure of the title compound (Fig. 1), the pyrrole ring, the boronic acid group and the carboxyl groups are almost co-planar. The carbonyl links with the adjacent boronic acid group via O3—H3···O2 hydrogen bonding. Intermolecular hydrogen bond is also observed in the crystal structure (Table 1).

Related literature top

For general background, see: Hall (2005); Kelly & Fuchs (1993).

Experimental top

All chemical reagents are commercial and used as received. Under -78°C and argon atmosphere, lithium diisopropylamide (1.0 M in THF, 5.0 ml, 5.0 mmol) was added dropwise to a solution of tert-butyl 1H-pyrrole-1-carboxylate (835 mg, 5.0 mmol) in dry THF (15 ml), and the solution was stirred at this temperature for 30 min. Trimethylborate (1.7 ml, 15 mmol) was added dropwise, and the mixture was allowed to warm to room temperature over 2 h and stirred overnight. After aqueous workup, the crude product was crystallized from hexanes. Single crystals suitable for X-ray analysis were obtained by recrystallization from a mixed solvent of ethyl acetate and hexane at ambient temperature (20–25°C).

Refinement top

H atoms were located in a difference Fourier map and refined isotropically.

Computing details top

Data collection: SMART (Bruker, 2001); cell refinement: SAINT (Bruker, 2001); data reduction: SAINT (Bruker, 2001); program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The molecular structure of the title compound with displacement ellipsoids drawn at the 50% probability level. H atoms are drawn as spheres of arbitrary radii.
Tert-butyl 2-borono-1H-pyrrole-1-carboxylate top
Crystal data top
C9H14BNO4F(000) = 896
Mr = 211.02Dx = 1.244 Mg m3
Orthorhombic, PbcaMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ac 2abCell parameters from 810 reflections
a = 13.014 (3) Åθ = 2.3–22.4°
b = 9.940 (2) ŵ = 0.10 mm1
c = 17.417 (4) ÅT = 293 K
V = 2252.9 (9) Å3Prism, colorless
Z = 80.25 × 0.12 × 0.10 mm
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
1208 reflections with I > 2σ(I)
Radiation source: fine-focus sealed tubeRint = 0.065
Graphite monochromatorθmax = 26.0°, θmin = 2.3°
ϕ and ω scansh = 1613
9542 measured reflectionsk = 1212
2213 independent reflectionsl = 2119
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.042Hydrogen site location: inferred from neighbouring sites
wR(F2) = 0.106All H-atom parameters refined
S = 0.85 w = 1/[σ2(Fo2) + (0.0588P)2]
where P = (Fo2 + 2Fc2)/3
2213 reflections(Δ/σ)max < 0.001
192 parametersΔρmax = 0.12 e Å3
0 restraintsΔρmin = 0.21 e Å3
Crystal data top
C9H14BNO4V = 2252.9 (9) Å3
Mr = 211.02Z = 8
Orthorhombic, PbcaMo Kα radiation
a = 13.014 (3) ŵ = 0.10 mm1
b = 9.940 (2) ÅT = 293 K
c = 17.417 (4) Å0.25 × 0.12 × 0.10 mm
Data collection top
Bruker SMART 1000 CCD area-detector
diffractometer
1208 reflections with I > 2σ(I)
9542 measured reflectionsRint = 0.065
2213 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0420 restraints
wR(F2) = 0.106All H-atom parameters refined
S = 0.85Δρmax = 0.12 e Å3
2213 reflectionsΔρmin = 0.21 e Å3
192 parameters
Special details top

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 (Å2) top
xyzUiso*/Ueq
B11.03949 (15)0.6990 (2)0.51802 (11)0.0727 (6)
C11.09811 (14)1.0494 (2)0.59196 (12)0.0767 (5)
C21.17519 (16)1.0274 (3)0.54329 (13)0.0893 (7)
C31.16298 (14)0.8995 (3)0.51194 (12)0.0821 (6)
C41.07732 (12)0.83956 (18)0.54116 (8)0.0644 (5)
C50.94986 (12)0.92187 (19)0.63777 (9)0.0635 (4)
C60.85439 (15)1.03344 (19)0.74024 (10)0.0771 (5)
C70.75166 (18)1.0282 (3)0.70204 (16)0.0955 (7)
C80.8711 (3)0.9215 (3)0.79700 (14)0.1000 (7)
C90.8746 (3)1.1693 (3)0.7756 (2)0.1119 (9)
N11.03646 (9)0.93560 (14)0.59221 (7)0.0631 (4)
O10.93714 (8)1.02801 (13)0.68119 (7)0.0754 (4)
O20.89519 (9)0.82427 (13)0.63724 (7)0.0776 (4)
O30.95566 (10)0.63485 (15)0.54641 (8)0.0921 (5)
O41.09809 (10)0.6338 (2)0.46635 (8)0.0960 (5)
H31.2044 (14)0.8510 (17)0.4741 (10)0.083 (5)*
H7A0.7006 (17)1.040 (2)0.7397 (13)0.104 (7)*
H7B0.7430 (18)1.106 (3)0.6664 (14)0.131 (10)*
H8A0.8247 (16)0.934 (2)0.8403 (14)0.109 (7)*
H11.0760 (14)1.126 (2)0.6241 (11)0.089 (6)*
H9A0.8259 (16)1.184 (2)0.8132 (14)0.122 (8)*
H9B0.8706 (15)1.236 (2)0.7359 (14)0.109 (9)*
H7C0.7384 (15)0.942 (2)0.6764 (13)0.104 (7)*
H21.2262 (17)1.090 (2)0.5323 (11)0.104 (7)*
H8B0.941 (2)0.928 (2)0.8167 (14)0.130 (9)*
H9C0.949 (2)1.169 (3)0.7937 (16)0.169 (12)*
H8C0.8565 (17)0.826 (3)0.7735 (14)0.135 (9)*
H3A0.9265 (14)0.6888 (19)0.5791 (11)0.087 (6)*
H41.080 (2)0.548 (3)0.4581 (16)0.145 (12)*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
B10.0572 (11)0.1046 (17)0.0563 (11)0.0146 (11)0.0040 (9)0.0053 (11)
C10.0616 (11)0.0916 (15)0.0767 (12)0.0077 (11)0.0134 (10)0.0135 (12)
C20.0590 (12)0.120 (2)0.0888 (15)0.0117 (12)0.0074 (11)0.0335 (14)
C30.0565 (11)0.1260 (19)0.0638 (11)0.0091 (12)0.0003 (9)0.0161 (13)
C40.0524 (9)0.0915 (13)0.0492 (8)0.0113 (9)0.0034 (7)0.0069 (9)
C50.0586 (10)0.0744 (12)0.0576 (9)0.0032 (9)0.0030 (8)0.0004 (9)
C60.0834 (13)0.0832 (13)0.0647 (11)0.0110 (10)0.0065 (9)0.0149 (10)
C70.0793 (15)0.116 (2)0.0913 (17)0.0166 (14)0.0054 (13)0.0170 (17)
C80.119 (2)0.115 (2)0.0655 (13)0.0172 (16)0.0126 (14)0.0019 (14)
C90.129 (2)0.103 (2)0.103 (2)0.0076 (16)0.0117 (18)0.0376 (18)
N10.0494 (7)0.0814 (10)0.0585 (8)0.0007 (7)0.0031 (6)0.0075 (7)
O10.0787 (8)0.0766 (8)0.0708 (7)0.0010 (6)0.0069 (6)0.0128 (7)
O20.0698 (7)0.0786 (9)0.0844 (8)0.0067 (6)0.0214 (6)0.0166 (7)
O30.0730 (8)0.1037 (11)0.0996 (10)0.0004 (7)0.0200 (7)0.0384 (8)
O40.0799 (9)0.1217 (14)0.0863 (9)0.0147 (8)0.0190 (7)0.0238 (9)
Geometric parameters (Å, º) top
B1—O41.346 (2)C6—C71.494 (3)
B1—O31.357 (2)C6—C81.504 (3)
B1—C41.535 (3)C6—C91.507 (3)
C1—C21.331 (3)C7—H7A0.94 (2)
C1—N11.387 (2)C7—H7B0.99 (3)
C1—H10.99 (2)C7—H7C0.98 (2)
C2—C31.393 (3)C8—H8A0.97 (2)
C2—H20.93 (2)C8—H8B0.98 (3)
C3—C41.363 (3)C8—H8C1.05 (3)
C3—H30.978 (18)C9—H9A0.92 (2)
C4—N11.409 (2)C9—H9B0.96 (2)
C5—O21.2030 (19)C9—H9C1.02 (3)
C5—O11.309 (2)O3—H3A0.87 (2)
C5—N11.385 (2)O4—H40.89 (3)
C6—O11.490 (2)
O4—B1—O3118.2 (2)C6—C7—H7A108.5 (13)
O4—B1—C4115.60 (19)C6—C7—H7B110.6 (14)
O3—B1—C4126.14 (17)H7A—C7—H7B105.0 (18)
C2—C1—N1107.7 (2)C6—C7—H7C112.9 (12)
C2—C1—H1135.0 (12)H7A—C7—H7C107.4 (18)
N1—C1—H1117.2 (11)H7B—C7—H7C112 (2)
C1—C2—C3108.3 (2)C6—C8—H8A109.2 (12)
C1—C2—H2123.9 (13)C6—C8—H8B108.4 (15)
C3—C2—H2127.8 (13)H8A—C8—H8B107 (2)
C4—C3—C2110.3 (2)C6—C8—H8C112.7 (13)
C4—C3—H3119.1 (11)H8A—C8—H8C107.5 (18)
C2—C3—H3130.7 (10)H8B—C8—H8C111 (2)
C3—C4—N1104.36 (18)C6—C9—H9A107.9 (16)
C3—C4—B1124.22 (18)C6—C9—H9B108.3 (13)
N1—C4—B1131.40 (15)H9A—C9—H9B112 (2)
O2—C5—O1125.44 (15)C6—C9—H9C107.0 (17)
O2—C5—N1123.79 (16)H9A—C9—H9C116 (2)
O1—C5—N1110.77 (15)H9B—C9—H9C106 (2)
O1—C6—C7109.75 (16)C5—N1—C1123.57 (16)
O1—C6—C8108.80 (16)C5—N1—C4127.01 (15)
C7—C6—C8113.4 (2)C1—N1—C4109.41 (16)
O1—C6—C9100.86 (18)C5—O1—C6121.30 (13)
C7—C6—C9111.6 (2)B1—O3—H3A107.4 (12)
C8—C6—C9111.6 (2)B1—O4—H4114.5 (18)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H4···O3i0.89 (3)1.88 (3)2.769 (3)173 (3)
O3—H3A···O20.87 (2)1.73 (2)2.5819 (18)164.7 (18)
Symmetry code: (i) x+2, y+1, z+1.

Experimental details

Crystal data
Chemical formulaC9H14BNO4
Mr211.02
Crystal system, space groupOrthorhombic, Pbca
Temperature (K)293
a, b, c (Å)13.014 (3), 9.940 (2), 17.417 (4)
V3)2252.9 (9)
Z8
Radiation typeMo Kα
µ (mm1)0.10
Crystal size (mm)0.25 × 0.12 × 0.10
Data collection
DiffractometerBruker SMART 1000 CCD area-detector
diffractometer
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
9542, 2213, 1208
Rint0.065
(sin θ/λ)max1)0.617
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.042, 0.106, 0.85
No. of reflections2213
No. of parameters192
H-atom treatmentAll H-atom parameters refined
Δρmax, Δρmin (e Å3)0.12, 0.21

Computer programs: SMART (Bruker, 2001), SAINT (Bruker, 2001), SHELXTL (Sheldrick, 2008).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
O4—H4···O3i0.89 (3)1.88 (3)2.769 (3)173 (3)
O3—H3A···O20.87 (2)1.73 (2)2.5819 (18)164.7 (18)
Symmetry code: (i) x+2, y+1, z+1.
 

Acknowledgements

We thank Professor Lin-Hong Weng, Fudan University, for the X-ray analysis.

References

First citationBruker (2001). SAINT and SMART. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationHall, D. G. (2005). Editor. Boronic Acids, Weinheim: Wiley-VCH.  Google Scholar
First citationKelly, T. A. & Fuchs, V. U. (1993). Tetrahedron 49, 1009–1016.  CSD CrossRef CAS Web of Science Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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ISSN: 2056-9890
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