E368
G.-N. Li, G.-Y. Chen, Z.-G. Niu, B.-X. Lei, and H.-J. Feng
Vol 51
Scheme 1
reported for previous structures [12–14]. The plane of the
Cp(2) ring is slightly twisted against the phenyl ring
(C11—C12—C13—C14—C15—C16), with the dihedral
angle being 20.21ꢀ. For the 1,3-dithiol-2-one molecule,
all bond lengths are within the expected range for neutral
TTF [15]. Besides, C(17)═O(1) bond length is 1.196 Å.
In conclusion, 1,3-dithiol-2-one derivatives via [4 + 2]
Diels–Alder cycloaddition reaction of 4,5-bis(dibromomethyl)-
1,3-dithiol-2-one (I) with vinyl-substituted compounds have
been synthesized. Single crystals of methyl 4-(2-oxobenzo[d]
[1,3]dithiol-5-yl)benzoate (IVf) and 2-oxobenzo[d][1,3]
dithiole-5-ferrocene (IVg) have been obtained by slow evapo-
ration of organic solvents. Detailed crystal structure analyses
have been performed to identify the molecular arrangement.
Spectral analyses have also been carried out.
Scheme 2
EXPERIMENTAL
All reagents and solvents were purchased from commercial
sources (Sigma-Aldrich, Alfa, and Shanghai Sinopharm compa-
nies) and used without further purification. 1H-NMR spectra were
recorded on a Bruker AM 500 instrument. Chemical shifts were
reported in parts per million relative to Me4Si as an internal stan-
dard. Elemental analyses for C, H, and N were performed on a
Perkine Elmer 240C analyzer. MALDI–TOF MS spectra were
recorded on an Autoflex II TM TOF/TOF instrument.
structure of products, single crystals of IVf and IVg were
prepared, and their structures were determined by X-ray
diffraction (Figure 1).
Crystal structures. The crystallographic data for IVf
and IVg are listed in Table 2; selected bond lengths and
bond angles are collected in Table 3. Oak Ridge thermal
ellipsoid plot drawings of the molecular structures for
IVf and IVg with the atomic numbering scheme are
given in Figure 1.
For the compound IVf, the C—S bonds are not equiva-
lent with bond lengths ranging from 1.737 to 1.762 Å. The
C(1)═O(1) bond length of the 1,3-dithiol-2-one derivative
is 1.203 Å and is within the range for a neutral TTF. The
planar-fused benzene (C2—C3—C4—C5—C6—C7) and
the five-membered rings (C1—S1—C2—C3—S2) are
almost coplanar with the average deviation from a least-
squares plane of 0.0111 Å. However, both phenyl rings
(C2—C3—C4—C5—C6—C7 and C8—C9—C10—
C11—C12—C13) in the molecule are twisted, the dihedral
angle being equal to 24.92ꢀ. The C—O bond lengths in
methyl ester groups are 1.324 Å for C(14)—O(2) and
1.189 Å for C(14)—O(3), respectively.
As for the compound IVg, both cyclopentadienyl (Cp)
rings in the ferrocene moiety are almost coplanar with the
average deviation from a least-squares plane of 0.0003
and 0.0018 Å, respectively. Also, the C—C bond lengths
vary from 1.379 to 1.425 Å for the two Cp rings. In addi-
tion, Fe1—Cp(1) (C1—C2—C3—C4—C5) and Fe1—Cp
(2) (C6—C7—C8—C9—C10) distances are 1.646 and
1.644 Å, respectively, which are in accord with those
Crystal structure determination of compound IVf and
IVg.
The crystals of IVf and IVg suitable for X-ray
structural analysis were obtained by slow evaporation of a
mixture solution of CH2Cl2 and MeOH. The data were collected
on a Bruker Smart Apex CCD diffractometer equipped with
graphite-monochromated Mo Ka (l = 0.71073 Å) radiation by
using a o ꢁ 2θ scan mode at 293 K. The data collection and
processing were performed using program SMART and SAINT
[16]. The structure solution, refinement, and geometrical
calculations were carried out through SHELX TL [17]. All
hydrogen atoms were added theoretically. Crystallographic data
for the structure analysis has been deposited at the Cambridge
Crystallographic Data Centre, CCDC Nos. 903836 and 903837.
Copies of these information can be obtained free of charge on
application to CCDC, 12 Union Road, Cambridge CB2 1EZ,
UK [fax: (44) 01223 336033 or e-mail: deposit@ccdc.cam.ac.uk].
General procedure for the synthesis of 1,3-dithiol-2-one
derivatives (IVa–IVh).
Under an argon atmosphere, the
reaction mixture of 4,5-bis(dibromomethyl)-1,3-dithiol-2-oneI
(2.00 mmol) and NaI (1.50 g, 10.00 mmol) in CH3CN/DMF
(5 mL) was heated at 70/110ꢀC. After 30 min, the solution of
vinyl-substituted compounds IIIa–IIIh (4.00 mmol) in CH3CN/
DMF (4 mL) was added, and the mixture solution was stirred
for 2–5 h at this temperature. The solvent was removed in
vacuum, and aqueous NaHSO3 was added. Finally, the reaction
mixture was extracted with ethyl acetate, and the combined
organic phase was washed with brine, dried over Na2SO4 and
concentrated in vacuum. The residues were purified by flash
chromatography to give compounds IVa–IVh.
5-(2,20-Bipyridin-5-yl)benzo[d][1,3]dithiol-2-one (IVa), 5-(pyri-
din-3-yl)benzo[d][1,3]dithiol-2-one (IVb) and 5-(pyridin-4-yl)
benzo[d][1,3]dithiol-2-one (IVc) were reported in the literature [10].
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet