organic compounds
Acta Crystallographica Section C
Crystal Structure
Communications
of our ongoing investigation of the synthesis and solid-state
reactivity of unsaturated pyridyl compounds (Linares &
Bricen˜o, 2010; Hill et al., 2012), we describe the molecular
structures of the title compounds, (I) and (II), which are
interesting precursors for the preparation of asymmetric
olefins via a condensation process.
ISSN 0108-2701
1-[5-(4,5-Dimethyl-1,3,2-dioxaboro-
lan-2-yl)thiophen-2-yl]ethanone and
4-(4,4,5,5-tetramethyl-1,3,2-dioxa-
borolan-2-yl)benzaldehyde
The molecule of (I) (Fig. 1) adopts a nearly planar confor-
mation. The acetyl and boronate ester substituents make
dihedral angles of 3.35 (6) and 2.96 (2)ꢀ, respectively, with the
mean plane of the thiophene ring. The methyl groups are
oriented in a trans configuration on the five-membered ring
formed by atoms B1/O2/C1/C2/O1. The B—O distances are
a
a
b
´
´
Neudo Urdaneta, * Jesus Nunez, Teresa Gonzalez and
˜
Alexander Bricenob*
˜
a
´
Laboratorio 210, Departamento de Quımica, Universidad Simon Bolivar (USB),
b
´
Apartado 47206, Caracas 1080-A, Venezuela, and Centro de Quımica, Instituto
´
Venezolano de Investigaciones Cientıficas, Apartado 21827, Caracas 1020-A,
˚
statistically similar, with B1—O1 = 1.363 (4) A and B1—O2 =
Venezuela
˚
1.347 (5) A. Likewise, the C—S [1.711 (3) and 1.712 (3) A]
˚
˚
˚
and C C [C3—C4 = 1.373 (4) A and C5—C6 = 1.362 (4) A]
distances from the thiophene ring are also similar, displaying
bond lengths typical for C—S single and C C double bonds,
Received 8 February 2012
Accepted 25 April 2012
Online 6 May 2012
˚
respectively [average C—S = 1.69 (8) A and average C C =
˚
1.34 (3) A (Cambridge structural Database, Version 5.32;
In both title compounds, C10H13BO3S, (I), and C13H17BO3,
(II), the molecules adopt nearly planar conformations. The
crystal packing of (I) consists of a supramolecular two-
dimensional network with a herringbone-like topology formed
by self assembly of centrosymmetric pairs of molecules linked
via dipole–dipole interactions. The crystal structure of (II)
consists of a supramolecular two-dimensional network built
up from centrosymmetric pairs of molecules via ꢀ–ꢀ inter-
actions. These pairs of molecules are self-organized in an
offset fashion related by a symmetry centre, generating
supramolecular ribbons running along the [101] direction.
Neighbouring ribbons are stacked via complementary van der
Waals and hydrophobic methyl–methyl interactions.
Allen, 2002)]. The carbonyl group is oriented cis to the S atom
of the thiophene ring, forming an S1—C6—C7—O3 torsion
angle of À1.7 (5)ꢀ.
The crystal structure of (I) consists of supramolecular layers
built up from centrosymmetric pairs of molecules linked by
dipole–dipole interactions between carbonyl and B—O
i
i
˚
˚
groups [B1 Á Á ÁO3 = 3.545 (5) A and O1 Á Á ÁC7 = 3.699 (5) A;
symmetry code: (i) Àx, Ày, Àz + 1] (Fig. 2b), generating a
herringbone-like supramolecular two-dimensional network
parallel to the bc plane (Fig. 2a). The three-dimensional array
is achieved by stacking of the layers through van der Waals
and hydrophobic methyl–methyl interactions.
The molecule of (II) (Fig. 3) deviates from planarity, with
the boronate ester group forming a dihedral angle of 7.53 (2)ꢀ
with the mean plane of the benzaldehyde group. The B—O
Comment
˚
˚
[B1—O1 = 1.348 (3) A and B1—O2 = 1.349 (3) A] distances in
(II) are similar.
Compounds containing boronate esters [RB(OR)2] represent
valuable intermediates in organic synthesis, particularly in the
Suzuki–Miyaura coupling reaction (Miyaura & Suzuki, 1995).
They are also well established compounds for the detection of
carbohydrates (Striegler, 2003), as a result of their ability to
¨
form cyclic esters with appropriate diols (Schnurch et al.,
2007). It has been found that some imines containing boronate
ester groups display antifungal behaviour against both
Aspergillus niger and A. flavus (Vogels et al., 2001). Crystal-
lographic studies related to the structure–property relation-
ship of boronate esters remain largely unexplored and only a
few crystal structures have been reported so far. In particular,
there is a crystallograhic report on the space group revision of
4-formylphenylboronic acid (Fronczek et al., 2001), where
both the formyl and B(OH)2 groups were found ordered, in
contrast with the previous report where these groups were
disordered (Feulner et al., 1990). In this contribution, as part
Figure 1
The molecular structure of (I), showing the atom-numbering scheme.
Displacement ellipsoids are drawn at the 35% probability level.
Acta Cryst. (2012). C68, o213–o215
doi:10.1107/S0108270112018598
# 2012 International Union of Crystallography o213
Urdaneta, Neudo
