tert-Butyl 2-(dihydroxyboryl)pyrrole-1-carboxylate

Tomasz Klis; Janusz Serwatowski

doi:10.1107/S1600536808013482

. 2008 May 10;64(Pt 6):o1054. doi: 10.1107/S1600536808013482

tert-Butyl 2-(dihydroxyboryl)pyrrole-1-carboxylate

Tomasz Klis ^a,^*, Janusz Serwatowski ^a

PMCID: PMC2961599 PMID: 21202573

Abstract

In the title compound, C₉H₁₄BNO₄, the carbonyl and boronic acid groups are essentially coplanar with the pyrrole ring and the boronic acid group has an exo-endo conformation. The exo-oriented OH is engaged in an intramolecular O—H⋯O interaction, while the endo-oriented one is involved in intermolecular hydrogen bonding to form centrosymmetric dimers. A supramolecular assembly is achieved through interactions involving the tert-butyl groups, forming infinite chains along the crystallographic b axis. There are, in addition, face-to-face and center-to-edge stacking interactions [distance between the pyrrole ring centroid and an N atom from a neighbouring molecule = 3.369 (8) Å].

Related literature

For related literature, see: Dabrowski et al. (2006 ▶); Parry et al. (2002 ▶); Saygili et al. (2004 ▶); Seminario et al. (1998 ▶); Thompson et al. (2005 ▶); Wang et al. (2002 ▶).

Experimental

Crystal data

C₉H₁₄BNO₄
M _r = 211.02
Orthorhombic,
a = 12.9179 (12) Å
b = 9.5885 (7) Å
c = 17.5811 (15) Å
V = 2177.7 (3) Å³
Z = 8
Mo Kα radiation
μ = 0.10 mm⁻¹
T = 100 (2) K
0.71 × 0.34 × 0.22 mm

Data collection

Kuma KM4 CCD diffractometer
Absorption correction: multi-scan (CrysAlis RED; Oxford Diffraction 2005 ▶) T _min = 0.95, T _max = 0.98
19290 measured reflections
2713 independent reflections
1911 reflections with I > 2σ(I)
R _int = 0.021

Refinement

R[F ² > 2σ(F ²)] = 0.031
wR(F ²) = 0.076
S = 0.96
2713 reflections
193 parameters
All H-atom parameters refined
Δρ_max = 0.26 e Å⁻³
Δρ_min = −0.19 e Å⁻³

Data collection: CrysAlis CCD (Oxford Diffraction, 2005 ▶); cell refinement: CrysAlis RED (Oxford Diffraction, 2005 ▶); data reduction: CrysAlis RED; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008 ▶); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008 ▶); molecular graphics: DIAMOND (Brandenburg, 1999 ▶); software used to prepare material for publication: SHELXL97.

Supplementary Material

Crystal structure: contains datablocks I, New_Global_Publ_Block. DOI: 10.1107/S1600536808013482/bg2173sup1.cif

e-64-o1054-sup1.cif^{(16.6KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536808013482/bg2173Isup2.hkl

e-64-o1054-Isup2.hkl^{(133.3KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

D—H⋯A	D—H	H⋯A	D⋯A	D—H⋯A
O1—H1O⋯O3	0.917 (15)	1.704 (15)	2.5941 (10)	162.9 (13)
O2—H2O⋯O1ⁱ	0.922 (16)	1.855 (17)	2.7728 (11)	173.7 (13)

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Symmetry code: (i) Inline graphic .

Acknowledgments

This work was supported by the Aldrich Chemical Company through the donation of chemicals and equipment and by the Warsaw University of Technology. The X-ray measurements were undertaken in the Crystallographic Unit of the Physical Chemistry Laboratory at the Chemistry Department of the University of Warsaw.

supplementary crystallographic information

Comment

Nitrogen-containing boronic acids are the object of interest to many chemists because of their application as potential saccharide sensors (Wang et al., 2002). However, no crystal structure of any boronic acid containing a pyrrole ring has been elucidated to date. The only crystal data concerning nitrogen-containing heterocyclic boronic acids involve some pyrydine (Parry et al., 2002), (Thompson et al., 2005), (Dabrowski et al., 2006) and pyrimidine (Saygili et al., 2004) derivatives.

The molecular structure of the title compound C₉H₁₄BO₄N (I) is shown in Fig. 1. The carbonyl and boronic acid groups are essentially coplanar with the pyrrole ring [torsion angles O3—C5—N1—C1 = -1.31 (1)° and N1—C1—B1—O1 = -2.8 (2)° respectively]. The conformation between C9 from the tert-butyl- and the carbonyl groups is antiperiplanar. The boronic acid group has an exo-endo conformation. The exo-oriented OH is engaged in an intramolecular O—H···O interaction with O3. The endo- oriented one, instead, is involved into intermolecular hydrogen bonding to form centrosymmetric dimers (Fig. 2). The supramolecular assembly is achieved through interactions involving tert-butyl groups, forming infinite chains along the crystallographic b axis. Examination of the crystal packing reveals the presence of face to face, center to edge stacking (FFCE) (Seminario et al., 1998). These interactions are represented by a relatively short distance (3.369 (8) Å) between the pyrrole ring centroid and the nitrogen atom from neighbouring molecules (Fig. 3).

Experimental

N-tert-butoxycarbonyl-pyrrole-2-boronic acid was obtained from Aldrich, crystallized from tetrahydrofurane and dried in air.