Fluorine hydrogen short contacts and hydrogen bonds in substituted benzamides

Article abstract of DOI:10.1016/j.jfluchem.2009.02.009

A series of fluorine substituted benzamides 1-10 was synthesised and investigated by spectroscopic methods (NMR, IR, MS) and X-ray structure analysis. The configuration of these compounds strongly depends on solvent, temperature and substitution pattern.

Full text of DOI:10.1016/j.jfluchem.2009.02.009

Journal of Fluorine Chemistry 130 (2009) 453–460
Contents lists available at ScienceDirect
Journal of Fluorine Chemistry
journal homepage: www.elsevier.com/locate/fluor
Fluorine hydrogen short contacts and hydrogen bonds in substituted benzamides
b
b
c
c
Lothar Hennig a, , Ketty Ayala-Leon , Jorge Angulo-Cornejo , Rainer Richter , Lothar Beyer
*
a University of Leipzig, Institute of Organic Chemistry, Johannisallee 29, D-04103 Leipzig, Germany
b Universidad Nacional Mayor de San Marcos, Facultad de Quimica e Ingenieria Quimica, Av. Venezuela s/n, Lima 1, Peru´
c University of Leipzig, Institute of Inorganic Chemistry, Johannisallee 29, D-04103 Leipzig, Germany
A R T I C L E I N F O
A B S T R A C T
Article history:
A series of fluorine substituted benzamides 1–10 was synthesised and investigated by spectroscopic
methods (NMR, IR, MS) and X-ray structure analysis. The configuration of these compounds strongly
depends on solvent, temperature and substitution pattern. Unexpectedly, some of these compounds
form weak intramolecular hydrogen bonds/short N–Hꢀ ꢀ ꢀF–C contacts in CDCl3 solution and in the solid
state.
Received 1 December 2008
Received in revised form 5 February 2009
Accepted 7 February 2009
Available online 21 February 2009
Dedicated to Prof. Dr. Klaus Burger on the
occasion of his 70th birthday.
ß 2009 Elsevier B.V. All rights reserved.
Keywords:
Fluorine substituted benzamides
Synthesis
NMR investigations
Crystal structures
Hydrogen bonds/short contacts
1. Introduction
2. Results and discussion
It is well-known that anionic fluorine forms very strong
hydrogen bonds, but in organic molecules Fꢀ ꢀ ꢀH interactions are
very rare [1]. Such interactions are traditionally indicated as
hydrogen bonds or characterised as non-conventional H-bonds,
weak hydrogen bonds (1.5–2.5 kcal molꢁ1) or short contacts to
A series of benzamide derivatives was synthesised by reaction
of substituted benzoyl chlorides with KSCN and secondary amines
(diethylamine, diisopropylamine, morpholine, diethanol amine) in
acetone (Scheme 1).
Analogously to 1 [7] the fluorine substituted compounds 2, 3, 5,
6, and 7 exist as NH tautomers in E/Z0 configuration with a partially
hindered rotation of the C(S)–N(R4)2 bond (Scheme 2). Tempera-
ture depending NMR measurements in DMSO-d6 showed that the
distinguish them from classical hydrogen bonds (5–10 kcal molꢁ1
[2,3]. A CSD analysis showed:
)
(a) Only 40 out of 1163 organic F atoms possibly accept a hydrogen
activation barrier of the fluorine substituted compounds is
¼
bond from OH or NH using a distance cut-off d < 2.35 A (3.4%).
marginally lower (e.g., 1: Tc = 345 K,
D
G
= 69.7 kJ molꢁ1; 2:
˚
¼
25 out of these 40 are intramolecular interactions [3].
(b) From 5947 C–F bonds in crystal structures with at least one
potential OH or NH donor only 37 are involved in possible O/N–
Tc = 336 K,
D
G
= 68.2 kJ molꢁ1). By contrast compounds 4 and
8–10 have a Z,Z0 configuration (see below).
Surprisingly, the 1H NMR spectra of the investigated com-
pounds 2, 3, and 7 are completely different concerning the NH
signal in DMSO-d6 and CDCl3 at room temperature. Whereas the
NH in DMSO-d6 appears as a singlet in the range from 10.5 to
11 ppm, the NH signal in CDCl3 gives a doublet with coupling
constants ranging from 9 to 12.2 Hz, and additionally the signal is
shifted to approximately 8.5 ppm (Table 1).
˚
Hꢀ ꢀ ꢀF hydrogen bonds with distances d < 2.3 A, i.e. 0.6% of the
potential F–C acceptors [4].
On investigation of fluorine substituted benzamides we now
found that these compounds represent a very sensitive system
concerning the formation of hydrogen bonds and/or short
contacts.
A five bond H–F coupling with such large coupling constants is
unusual. Normally a proton–fluorine coupling via 5 bonds is less
than 1 Hz. Therefore, the large coupling should be caused by
coupling ‘through space’. This unexpected behaviour was already
observed in 2-fluoro-benzamides earlier. The solvent dependence
* Corresponding author. Tel.: +49 341 9736560.
E-mail address: hennig@chemie.uni-leipzig.de (L. Hennig).
0022-1139/$ – see front matter ß 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jfluchem.2009.02.009

454
L. Hennig et al. / Journal of Fluorine Chemistry 130 (2009) 453–460
Scheme 1.
Scheme 2.
Table 1
sign of the Hꢀ ꢀ ꢀF and Nꢀ ꢀ ꢀF coupling constant [9]. Only much later it
NH chemical shifts of 1–10 in DMSO-d6 and CDCl3.
was found that in intermolecular Nꢀ ꢀ ꢀHꢀ ꢀ ꢀF systems such couplings
reflect the strength of the NHF hydrogen bond [10]. Recently
Fꢀ ꢀ ꢀH–N interactions in solution were used to control the
conformation in the synthesis of new foldamers [11].
Nr.
NH
DMSO-d6
CDCl3
1
2
10.52
10.64
10.68
11.08
10.58
8.45(br)
10.95
10.88
10.86
10.86
8.44 s (br)
Obviously, the weak intramolecular Fꢀ ꢀ ꢀH–N interaction in
CDCl3 is replaced in DMSO-d6 by formation of an intermolecular
hydrogen bond from NH to the solvent. This was confirmed by
NMR spectra of 5 and 9 in CDCl3. As expected no Fꢀ ꢀ ꢀH–N
interaction was observed for the 4-fluorine substituted product 5
(NH as a broad singlet at 8.59 ppm). The NH of 9 appears as a
broadened singlet which is shifted to 9.42 ppm. This means that
already the introduction of polar hydroxy groups prevents the
Fꢀ ꢀ ꢀH short contact.
8.61 d (J = 10.6 Hz)
8.51 d (J = 9.0 Hz)
not observed (H-D exchange)
8.59 s (br)
3
4
5
6
8.38 s (br)
7
8.84 d (J = 12.2 Hz)
(not enough soluble)
9.42 (br) (limited solubility)
(not enough soluble)
8
9
10
The Fꢀ ꢀ ꢀN–H interaction in CDCl3 could additionally be
confirmed by 19F NMR spectra and decoupling experiments. The
19F signal of 7 in CDCl3 shows a stronger coupling (ꢁ111.7 ppm;
coupling with aromatic protons and NH) than in DMSO-d6
(ꢁ113.9 ppm; only coupling with aromatic protons) (Fig. 1).
and the large ‘through space’ hydrogen–fluorine coupling were
explained with transmission of nuclear spin information via
hydrogen bonds [8]. This was supported by NMR investigations of
15N labelled 2-fluoro-benzamide and the detection of the negative
Fig. 1. 19F NMR spectra of 7 in CDCl3 (a) and DMSO-d6 (b).

L. Hennig et al. / Journal of Fluorine Chemistry 130 (2009) 453–460
455
Fig. 2. 1H,19F-HOESY spectra of 7 in DMSO-d6 (left) and CDCl3 (right).
Fig. 3. 1H,19F HOESY spectrum of 3 in CDCl3.
Proton decoupling leads to a simplification of the 19F NMR
signal. Vice versa, fluorine decoupling furnishes in the 1H spectrum
only a singlet for the NH proton.
Moreover, the measurement of two dimensional 1H,19F HOESY
spectra (fluorine-proton correlation depending on their spatial
distance) is a powerful tool for the detection of Fꢀ ꢀ ꢀH–N short
contacts in solution. E.g., while only one correlation cross peak
between fluorine (ꢁ113.9 ppm) and the aromatic proton in 3-
position of the phenyl substituent (7.29 ppm) was found for 7 in
DMSO-d6, two cross peaks were observed in CDCl3. Here
additionally a cross peak between fluorine (ꢁ111.7 ppm) and
NH (8.84 ppm) appears (Fig. 2).
Hence, a short contact/weak hydrogen bond between fluorine
and NH exits in CDCl3 which is not the case in DMSO-d6. This is due
to a stronger intermolecular hydrogen bond formation from NH to
the solvent (DMSO).
Scheme 3.
Fig. 4. NH signal in the IR spectrum of 1 and 2 in KBr.

456
L. Hennig et al. / Journal of Fluorine Chemistry 130 (2009) 453–460
Fig. 5. Molecular structure of 2.
˚
Selected bond lengths (A):
S1-C1 1.664(3), O1-C2 1.210(3), N1-C1 1.421(3), N1-C2 1.370(3), N2-C1 1.322(3), C2-C3 1.500(3), F1-C4 1.349(3).
Table 2
and 1208) than that of intermolecular interactions (mainly 130–
1708) [3].
X-ray structure determinations were performed with the
˚
Bond lengths (A) and angles (8) for possible intramolecular Fꢀ ꢀ ꢀH–N hydrogen
bridges/short contacts.
2
4
6
7
10
fluorine substituted benzamides 2, 4, 6, 7 and 10. The molecular
structures of these five compounds are shown in Figs. 5–9.
The parameters important for possible Fꢀ ꢀ ꢀH bridges/short
contacts are summarised in Table 2.
N–H
0.84(3)
2.69(3)
2.820(3)
0.82(2)
2.83(2)
3.037(2)
0.80(2)
2.26(2)
2.723(2)
0.84(2)
2.42(2)
2.696(2)
0.87(2)
Hꢀ ꢀ ꢀF
3.36(2)#
3.668(2)#
104(2)#
24.5(2)
Nꢀ ꢀ ꢀF
N–Hꢀ ꢀ ꢀF
90(2)
97(2)
117(2)
16.2(2)
100(2)
29.3(1)
The distance Fꢀ ꢀ ꢀH is much smaller than the sum of the van der
C3–C8/O1N1C2 46.3(1)
64.8(1)
˚
˚
Waals radii in 6 (2.26 A) and 7 (2.42 A), equals this sum in 2
#
˚
˚
Shortest intermolecular contact.
(2.69 A) and exceeds it in 4 (2.84 A). In 10 intramolecular
interactions between N1 and F1 are not possible. The Fꢀ ꢀ ꢀH–N
angles are in agreement with the formulated criteria for 6 and 7
and are slightly smaller for 2 and 4.
The usefulness of the HOESY method was also demonstrated
with compound 3 which contains two fluorine atoms in 2- and
4-position of the phenyl ring, respectively. In the proton
spectrum we observed three different signals for the aromatic
protons (6.91, 7.02 and 8.04 ppm) and two signals in the fluorine
spectrum (ꢁ107.4 and ꢁ101.8 ppm). The NH at 8.51 ppm
furnished a doublet with a coupling constant of 9 Hz caused
by interaction of F1 and NH. This interaction was again detected
in the 2D-HOESY spectrum (among another contact of F1 to Ha).
From the second fluorine atom F2 only contacts to Ha and Hb
were found (Fig. 3).
In further studies the 2,6-bis-fluorinated compound 4 was
investigated. Nearly no absorption for the NH was observed in
the CDCl3 NMR spectrum of 4 because H-D exchange with the
solvent occurs. Otherwise, in DMSO-d6 the expected singlet
appears at 11.08 ppm. In the fluorine spectra only one signal was
In this respect the criteria for the formation of weak
intramolecular interactions between C–Fꢀ ꢀ ꢀH–N in the solid state
[1,3,4] are fulfilled by 6 and 7, possibly also by 2. In 4 the distance
˚
˚
Fꢀ ꢀ ꢀH exceeds 2.70 A considerably (2.83 A) because the bis-
fluorinated phenyl ring is strongly twisted against the plane
O1N1C2 (64.88). Hence, the introduction of the second fluorine in
ortho-position also prevents the Fꢀ ꢀ ꢀH–N contact in solid state for
steric reasons.
Most remarkably, the introduction of hydroxy groups in the
amine part of the molecule by using diethanol amine in the
synthesis of 8–10 changes the stereochemistry from the E,Z0
configuration of 1–3 and 5–7 to a Z,Z0 configuration with formation
of an intramolecular N–Hꢀ ꢀ ꢀO hydrogen bond [6b,13].
Obviously, this intramolecular hydrogen bond formation
dominates in comparison to the intramolecular Fꢀ ꢀ ꢀH–N interac-
tion possible for 9. In 10 an intramolecular Fꢀ ꢀ ꢀH–N bridge
formation is not possible and no intermolecular Fꢀ ꢀ ꢀH–N bridges
were found in the crystal structure.
In spite of the possibly different behaviour in solution and in
solid state the results of the X-ray determinations do not oppose
the results of the NMR investigations and also give indication at
Hꢀ ꢀ ꢀF hydrogen bridges/short contacts in some of these com-
pounds.
found (DMSO-d6: ꢁ114.4 ppm; CDCl3: ꢁ111.7 ppm). As
a
consequence the introduction of the second fluorine in ortho-
position prevents the Fꢀ ꢀ ꢀH–N contact for electronic and steric
reasons.
Remarkably, already the synthesis of 4 differs in comparison to
the other compounds. The introduction of a second fluorine atom
in ortho-position results in the preferred formation of diethyl
ammonium salt 40 (Scheme 3).
The IR spectra of the fluorine and non-fluorine substituted
compounds are almost identical. However, a closer look at the NH
absorption (e.g., in comparison of 1 and 2) shows a significant red
shift (90 cmꢁ1) of the non-fluorinated compound (Fig. 4). This
phenomenon is well-known in IR spectroscopy and characteristic
for hydrogen bond formation [12].
An evidence for the existence of hydrogen bonds/short
contacts in solid state is the distance of the relevant atoms which
should be less than the sum of the van der Waals radii. In case of
Unexpectedly, the hydroxyethyl substituted compound 8 can
be oxidised easily to give an oxathiazine derivative 11 [14].
3. Conclusions
Fluorine takes more and more a leading part as a substituent in
organic compounds and especially in biologically active sub-
stances. It is known that fluorine atoms form short contacts or
weak hydrogen bonds in rare cases. We found with fluorine
˚
Hꢀ ꢀ ꢀF this would be a distance less than 2.70 A. A scatter plot of
substituted benzamides a system which is very sensitive
potential hydrogen bonds summarising Fꢀ ꢀ ꢀH–N angle versus
concerning hydrogen bond formation and Fꢀ ꢀ ꢀH–N short contacts.
The ability to measure these interactions by X-ray, NMR, and IR
may be important in structure-activity investigations of fluorine
substituted active compounds [15].
2
˚
Fꢀ ꢀ ꢀH distance shows that at sp carbons the distance is 2.2–2.4 A
in the most cases and the angle varies between 908 and 1708. The
angle of intramolecular contacts is smaller (mainly between 1008

L. Hennig et al. / Journal of Fluorine Chemistry 130 (2009) 453–460
457
Fig. 6. Molecular structure of 4.
˚
Selected bond lengths (A):
S1-C1 1.656(2), O1-C2 1.224(2), N1-C1 1.426(2), N1-C2 1.344(2), N2-C1 1.323(2), C2-C3 1.504(2), F1-C4 1.350(2), F2-C8 1.348(2).
Fig. 7. Molecular structure of 6.
˚
Selected bond lengths (A):
S1-C1 1.667(1), O1-C2 1.218(2), N1-C1 1.434(1), N1-C2 1.362(2), N2-C1 1.324(2), C2-C3 1.498(2), F1-C4 1.351(2).
4. Experimental
were corrected for Lorentz and polarization effects and for
absorption using SADABS.
Melting points were determined on Boetius micro-melting-
point apparatus and are corrected. NMR spectra were recorded
with Varian Gemini 2000, Varian Mercury Plus 300, Varian
Mercury Plus 400 and Bruker DRX-600 spectrometers. Residual
solvent signals were used as internal chemical shift references for
The structures were solved by direct methods and refined by
least-squares on weighted F2 values for all reflections. All non-
hydrogen atoms were refined with anisotropic displacement
parameters [16]. In 7 the atom F1 is disordered by bonding to
C4 (91%) and C8 (9%).
proton (DMSO-d6:
(DMSO-d6: 39.52 ppm; CDCl3:
were referenced to CCl3F ( 0 ppm). Mass spectra were measured
on a VG ZAB-HSQ (VG Analytics) and HRMS spectra in positive
mode on a FT-ICR-MS APEX II (Bruker Daltonics) spectrometer. IR
spectra were recorded with an AVATAR 360 FT-IR spectrometer
(Thermo Nicolet). Elemental analyses were performed on a
Heraeus CHNO Rapid Analyzer.
d
2.50 ppm; CDCl3:
d 7.26 ppm) and carbon
The positions of most of the hydrogen atoms were taken from
difference syntheses and refined with isotropic displacement
parameters. Calculated hydrogen positions without refinement
were only used in 2 (H at the diethyl groups) and in 7 (H at the
disorder positions at C4 and C8).
CCDC-708959 (2), CCDC-708960 (4), CCDC-708961 (6), CCDC-
708962 (7) and CCDC-708963 (10) contain the supplementary
crystallographic data for this paper. These data can be obtained
free of charge via www.ccdc.cam.uk/conts/retrieving.html (or from
the CCDC, 12 Union Road, Cambridge CB2 1EZ, UK; fax: +44 1223
336033; e-mail: deposit@ccdc.cam.ac.uk).
d
d
77.16 ppm), fluorine spectra
d
The data for the crystal structure determinations were collected
on a Bruker SMART CCD area-detector diffractometer with Mo K
˚
radiation (l = 0.71073 A) at temperature of 220 K. The intensities
a
Fig. 8. Molecular structure of 7.
˚
Selected bond lengths (A):
S1-C1 1.669(1), O1-C2 1.216(2), N1-C1 1.410(2), N1-C2 1.379(2), N2-C1 1.331(2), C2-C3 1.495(2), F1-C4 1.342(2).

458
L. Hennig et al. / Journal of Fluorine Chemistry 130 (2009) 453–460
Fig. 9. Molecular structure of 10.
˚
Selected bond lengths (A):
S1-C1 1.678(2), O1-C2 1.214(2), N1-C1 1.392(2), N1-C2 1.379(2), N2-C1 1.337(2), C2-C3 1.497(2), F1-C6 1.362(2).
4.1. General procedure for the synthesis of 1–10
1H NMR (300.06 MHz, CDCl3):
d 1.32 (br, 6H, CH3), 3.60 (br,
2H, CH2), 4.00 (br, 2H, CH2), 6.91 (m, 1H, H-3-Phenyl), 7.02 (m,
1H, H-5-Phenyl), 8.04 (m, 1H, H-6-Phenyl), 8.51 (d, 1H, NH,
J = 9.0 Hz);
A modified method of [17] has been used for the preparation of
the benzamides:
To 0.05 mol KSCN in 100 ml of boiling dry acetone 0.05 mol of
the corresponding benzoyl chloride were added dropwise. The
mixture was kept at 50 8C for 2 h, and then 0.075 mol amine in a
solution of hot acetone were added. After the reaction was
completed the mixture was cooled to room temperature and
stored in the refrigerator. The separated precipitate was collected
and crystallized from acetone (1, 40, 6, 7, 9, 10), a mixture of
acetone/ethanol 1:1 (2, 3, 5) or methanol (8). In case of 4 conc. HCl
was added before storing in the refrigerator, and the product was
crystallized from ethanol.
(400.02 MHz, DMSO-d6): d 1.21 (br, 6H, CH3), 3.58 (q, 2H, CH2),
3.91 (q, 2H, CH2), 7.19 (m, 1H, H-3-Phenyl), 7.36 (m, 1H, H-5-
Phenyl), 7.68 (m, 1H, H-6-Phenyl), 10.68 (s, 1H, NH);
13C (75.45 MHz, CDCl3):
d
11.47 (CH3), 13.33 (CH3), 47.84 (CH2),
48.03 (CH2), 104.80 (dd, 2JC,F = 28.1 Hz, 2JC,F = 25.8 Hz, C-3-Phenyl),
2
4
112.92 (dd, JC,F = 21.2 Hz, JC,F = 3.4 Hz, C-5-Phenyl), 116.68 (dd,,
2JC,F = 11.5 Hz,
4JC,F = 4.0 Hz,
C-1-Phenyl),
134.24
3
(dd,
3
3JC,F = 10.3 Hz, JC,F = 3.4 Hz, C-6-Phenyl), 159.07 (d, JC,F = 4.0 Hz,
CO), 161.19 (d, 1JC,F = 251.8 Hz, 3JC,F = 12.6 Hz, C-2-Phenyl), 165.74
1
3
(d, JC,F = 257.3 Hz, JC,F = 12.6 Hz, C-4-Phenyl), 178.38 (CS);
19F NMR (282.34 MHz, CDCl3):
d
ꢁ101.8, ꢁ107.2;
4.2. N-(Diethylcarbamothioyl)benzamide (1) [5]
Colorless crystals, mp 98–99 8C;
HRMS (ESI) m/z calcd. for C12H14F2N2OS: 273.0868 (M + H)+,
found 273.0864.
1H NMR (200.14 MHz, CDCl3):
d
1.31 (br, 6H, CH3), 3.59 (br, 2H,
4.5. N-(Diethylcarbamothioyl)-2,6-difluorobenzamide (4)
CH2), 3.99 (br, 2H, CH2), 7.81 (2H, H-2,6-Phenyl), 7.40–7.60 (3H, H-
3,4,5-Phenyl), 8.44 (br, 1H, NH);
1H NMR (400.02 MHz, CDCl3):
d 1.33 (t, 6H, CH3), 3.67 (br, 2H,
(600.13 MHz, DMSO-d6):
d
1.18 (t, 3H, CH3), 1.25 (t, 3H, CH3),
CH2), 3.96 (br, 2H, CH2), 6.97 (t, 2H, H-3,5-Phenyl), 7.42 (m, 1H, H-
4-Phenyl);
3.52 (q, 2H, CH2), 3.95 (q, 2H, CH2), 7.50 (t, 2H, H-3,5-Phenyl)
7.59 (t, 1H, H-4-Phenyl), 7.92 (d, 2H, H-2,6-Phenyl), 10.52 (s, 1H,
NH);
(400.02 MHz, DMSO-d6):
d 1.21 (t, 6H, CH3), 3.62 (q, 2H, CH2),
3.90 (q, 2H, CH2), 7.18 (t, 2H, H-3,5-Phenyl) 7.55 (m, 1H, H-4-
Phenyl), 11.08 (s, 1H, NH);
13C (50.33 MHz, CDCl3):
d 11.60 (CH3), 13.33 (CH3), 47.86
(2xCH2), 128.07 (C-3,5-Phenyl), 129.05 (C-2,6-Phenyl), 132.87 (C-
1-Phenyl), 132.97 (C-4-Phenyl), 163.84 (CO), 179.45 (CS).
Anal Calc. for C12H14F2N2OS: C, 52.9; H, 5.1; N, 10.3; S 11.8.
Found: C, 53.0; H, 5.2; N, 10.0; S, 12.0.
Diethyl ammonium salt 40,
4.3. N-(Diethylcarbamothioyl)-2-fluorobenzamide (2)
Colorless crystals, mp 93–94 8C;
C
16H25F2N3OS (345.46); mp108–110 8C;
1H NMR (200.14 MHz, DMSO-d6):
d
1.13 (t, 6H, CH3-salt), 1.21
(br, 3H, CH3), 1.23 (br, 3H, CH3), 2.58 (q, 4H, NCH2-salt), 3.64 (br,
2H, CH2), 3.91 (br, 2H, CH2), 6.59 (br, 2H, NH2-salt), 6.88 (t, 2H, H-
3,5-Phenyl), 7.25 (m, 1H, H-4-Phenyl);
1H NMR (200.14 MHz, CDCl3):
d 1.26 (br, 6H, CH3), 3.57 (br, 2H,
CH2), 3.94 (br, 2H, CH2), 7.10 (m, 1H, H-3-Phenyl), 7.21 (m, 1H, H-5-
Phenyl), 7.45 (m, 1H, H-4-Phenyl), 7.92 (m, 1H, H-6-Phenyl), 8.61
(d, 1H, NH, J = 10.6 Hz);
13C (50.33 MHz, CDCl3):
d 11.90 (CH3), 12.81 (CH3-salt), 13.56
(CH3), 43.69 (NCH2-salt), 45.71 (CH2), 46.77 (CH2), 111.76 (m,
2
(200.14 MHz, DMSO-d6):
d
1.25 (br, 3H, CH3), 1.32 (br, 3H, CH3),
AXX’, C-3,5-Phenyl), 117.97 (t, JC,F = 21.9 Hz, C-1-Phenyl), 130.22
3
3.63 (br, 2H, CH2), 4.03 (br, 2H, CH2), 7.22–7.34 (m, 2H, Phenyl),
7.51–7.64 (m, 2H, Phenyl), 10.64 (s, 1H, NH);
(t, JC,F = 9.9 Hz, C-4-Phenyl), 157.81 (br, CO), 159.86 (dd,
1JC,F = 249.8 Hz, JC,F = 8.0 Hz, C-2,6-Phenyl), 185.99 (CS);
3
13C (50.33 MHz, CDCl3):
(2xCH2), 116.51 (d, JC,F = 24.0 Hz, C-3-Phenyl), 120.09 (d,
2JC,F = 11.1 Hz, C-1-Phenyl), 125.16 (d, JC,F = 3.4 Hz, C-5-Phenyl),
d
11.52 (CH3), 13.35 (CH3), 47.91
19F NMR (376.39 MHz, CDCl3):
d
ꢁ111.7, (DMSO-d6): ꢁ114.4.
d
2
Anal Calc. for C16H25F2N3OS: C, 55.6; H, 7.3; N, 12.2; S 9.3.
Found: C, 55.6; H, 7.1; N, 11.9; S, 8.8.
4
132.33 (d, 3JC,F = 1.5 Hz, C-6-Phenyl), 134.81 (d, 3JC,F = 9.5 Hz, C-4-
Phenyl), 159.87 (d, 3JC,F = 3.4 Hz, CO), 160.68 (d, 1JC,F = 249.9 Hz, C-
2-Phenyl), 178.50 (CS);
4.6. N-(Diethylcarbamothioyl)-4-fluorobenzamide (5)
Colorless crystals, mp 133–135 8C;
19F NMR (188.32 MHz, CDCl3):
d
ꢁ112.0;
HRMS (ESI) m/z calcd. for C12H15FN2OS: 255.0962 (M + H)+,
1H NMR (200.14 MHz, CDCl3):
d 1.31 (br, 6H, CH3), 3.59 (br, 2H,
found: 255.0961.
CH2), 3.99 (br, 2H, CH2), 7.11 (t, 2H, H-3,5-Phenyl), 7.84 (t, 2H, H-
2,6-Phenyl), 8.59 (br, 1H, NH);
4.4. N-(Diethylcarbamothioyl)-2,4-difluorobenzamide (3)
Colorless crystals, mp 71–72 8C;
(300.06 MHz, DMSO-d6): d 1.20 (t, 3H, CH3), 1.22 (t, 3H, CH3),
3.51 (q, 2H, CH2), 3.94 (q, 2H, CH2), 7.33 (t, 2H, Phenyl), 8.00 (dd,
2H, Phenyl), 10.58 (s, 1H, NH);

L. Hennig et al. / Journal of Fluorine Chemistry 130 (2009) 453–460
459
13C (50.33 MHz, CDCl3):
d
11.56 (CH3), 13.37 (CH3), 47.73 (CH2),
1H NMR (600.13 MHz, H,H-COSY, HMQC, HMBC, DMSO-d6):
d
3.71 (m, 2H, OCH2), 3.74 (m, 2H, OCH2), 3.79 (t, 2H, NCH2), 3.94 (t,
2H, NCH2), 4.89 (t, 1H, OH), 5.71 (br, 1H, OH), 7.28 (m, 1H, H-3-
Phenyl), 7.29 (m, 1H, H-5-Phenyl), 7.56 (m, 1H, H-4-Phenyl), 7.62
(m, 1H, H-6-Phenyl), 10.86 (s, 1H, NH);
2
48.00 (CH2), 116.01 (d, JC,F = 22.2 Hz, C-3,5-Phenyl), 128.84 (d,
4JC,F = 2.5 Hz, C-1-Phenyl), 130.59 (d, JC,F = 9.5 Hz, C-2,6-Phenyl),
3
1
163.01 (CO), 165.59 (d, JC,F = 254.5 Hz, C-4-Phenyl), 179.36 (CS);
19F NMR (188.32 MHz, CDCl3):
d
ꢁ105.9;
HRMS (ESI) m/z calcd. for C12H15FN2OS: 255.0962 (M + H)+,
(600.13 MHz, CDCl3): d 3.48 (br, 1H, OH), 3.76 (br, 1H, OH),
found 255.0959.
3.88–3.94 (br, 4H, NCH2/OCH2), 4.08–4.14 (br, 4H, NCH2/OCH2),
7.17 (m, 1H, H-3-Phenyl), 7.28 (m, 1H, H-5-Phenyl), 7.55 (m, 1H, H-
4-Phenyl), 7.98 (m, 1H, H-6-Phenyl), 9.42 (br, 1H, NH);
4.7. N-(Diisopropylcarbamothioyl)-2-fluorobenzamide (6)
Colorless crystals, mp 100–101 8C;
13C (150.90 MHz, HMQC, HMBC, DMSO-d6):
d 54.92 (NCH2),
55.02 (NCH2), 57.62 (OCH2), 59.22 (OCH2), 116.19 (d, 2JC,F = 21.7 Hz,
1H NMR (200.14 MHz, CDCl3):
d
1.47 (br, 12H, CH3), 4.37 (br, 2H,
C-3-Phenyl), 123.47 (d, JC,F = 13.4 Hz, C-1-Phenyl), 124.58 (d,
2
3
CH), 7.14 (m, 1H, H-3-Phenyl), 7.26 (m, 1H, H-5-Phenyl), 7.48 (m,
1H, H-4-Phenyl), 8.03 (m, 1H, H-6-Phenyl), 8.38 (br, 1H, NH);
4JC,F = 3.4 Hz, C-5-Phenyl), 130.26 (d, JC,F = 2.7 Hz, C-6-Phenyl),
3
3
133.33 (d, JC,F = 8.8 Hz, C-4-Phenyl), 163.02 (d, JC,F = 1.3 Hz, CO),
159.24 (d, 1JC,F = 250.3 Hz, C-2-Phenyl), 180.44 (CS);
(300.05 MHz, DMSO-d6): d 1.20 (d, 12H, CH3), 3.32 (sep, 2H, CH),
7.04 (m, 1H, H-3-Phenyl), 7.13 (m, 1H, H-5-Phenyl), 7.39 (m, 1H, H-
4-Phenyl), 7.84 (m, 1H, H-6-Phenyl), 8.45 (br, 1H, NH);
19F NMR (564.62 MHz, DMSO-d6):
MS: m/z 286 [M]+ (2), 123 (100);
d
ꢁ112.3;
13C (50.33 MHz, CDCl3):
d
19.96 (br, CH3), 52.21 (br, CH), 116.40
Anal. Calc for C12H15FN2O3S: C, 50.3; H, 5.3; N, 9.8; S 11.2.
Found: C, 50.1; H, 5.7; N, 9.7; S, 11.6.
2
2
(d, JC,F = 24.4 Hz, C-3-Phenyl), 120.41 (d, JC,F = 11.1 Hz, C-1-
4
Phenyl), 125.07 (d, JC,F = 3.4 Hz, C-5-Phenyl), 132.335 (d,
3JC,F = 1.5 Hz, C-6-Phenyl), 134.56 (d, JC,F = 9.5 Hz, C-4-Phenyl),
4.11. N-[Bis(2-hydroxyethyl)carbamothioyl]-4-fluorobenzamide (10)
Colorless crystals, mp 154–156 8C;
3
160.64 (br, CO), 160.66 (d, 1JC,F = 249.5 Hz, C-2-Phenyl), 177.76 (br,
CS);
19F NMR (564.62 MHz, CDCl3):
d
ꢁ112.1;
1H NMR (600.13 MHz, H,H-COSY, HMQC, HMBC, DMSO-d6):
d
MS: m/z 282 [M]+ (44), 123 (100);
3.69 (br, 2H, OCH2), 3.71 (br, 2H, NCH2), 3.76 (m, 2H, OCH2), 3.99 (t,
2H, NCH2), 4.85 (t, 1H, OH), 5.56 (br, 1H, OH), 7.33 (m, 2H, H-3,5-
Phenyl), 7.93 (m, 2H, H-2,6-Phenyl), 10.86 (s, 1H, NH);
Anal. Calc for C14H19FN2OS: C, 59.6; H, 6.8; N, 9.9; S 11.4. Found:
C, 59.2; H, 6.7; N, 9.9; S, 11.4.
13C (150.90 MHz, HMQC, HMBC, DMSO-d6):
d 55.05 (NCH2),
4.8. 2-Fluoro-N-(morpholine-4-carbamothioyl)benzamide (7)
Colorless crystals, mp 141–142 8C;
55.09 (NCH2), 57.51 (OCH2), 59.17 (OCH2), 115.57 (d,
2JC,F = 22.1 Hz, C-3,5-Phenyl), 130.01 (d, 4JC,F = 3.1 Hz, C-1-Phenyl),
3
130.70 (d, JC,F = 9.5 Hz, C-2,6-Phenyl), 163.50 (CO), 164.47 (d,
1H NMR (600.13 MHz, CDCl3):
d
3.68 (br, 2H, NCH2), 3.84 (br,
1JC,F = 250.3 Hz, C-4-Phenyl), 181.09 (CS);
2H, OCH2), 3.84 (br, 2H, NCH2), 4.23 (br, 2H, OCH2), 7.18 (m, 1H, H-
3-Phenyl), 7.29 (m, 1H, H-5-Phenyl), 7.56 (m, 1H, H-4-Phenyl), 8.02
(m, 1H, H-6-Phenyl), 8.84 (d, 1H, NH, J = 12.2 Hz);
19F NMR (564.62 MHz, DMSO-d6):
MS: m/z 286 [M]+ (24), 154 (100);
d
ꢁ108.0;
Anal. Calc for C12H15FN2O3S: C, 50.3; H, 5.3; N, 9.8; S 11.2.
Found: C, 50.3; H, 5.4; N, 9.4; S, 11.4.
(600.13 MHz, H,H-COSY, HMQC, HMBC, DMSO-d6):
d 3.67 (br,
2H, NCH2), 3.68 (br, 2H, OCH2), 3.71 (br, 2H, OCH2), 4.13 (br, 2H,
OCH2), 7.29 (m, 1H, H-3-Phenyl), 7.30 (m, 1H, H-5-Phenyl), 7.58
(m, 1H, H-4-Phenyl), 7.64 (m, 1H, H-6-Phenyl), 10.95 (s, 1H, NH);
Acknowledgments
13C (150.90 MHz, HMQC, HMBC, DMSO-d6):
d 50.28 (br, NCH2),
We are grateful to Deutsche Akademische Austauschdienst for
financial support, and we thank Dr. Michael Kampf for preparation
of 4.
2
51.07 (br, NCH2), 65.62 (2xOCH2), 116.16 (d, JC,F = 21.8 Hz, C-3-
2
Phenyl), 122.99 (d, JC,F = 13.7 Hz, C-1-Phenyl), 124.42 (d,
3
4JC,F = 3.8 Hz, C-5-Phenyl), 130.24 (d, JC,F = 2.3 Hz, C-6-Phenyl),
133.41 (d, 3JC,F = 8.4 Hz, C-4-Phenyl), 159.37 (d, 1JC,F = 251.0 Hz, C-
References
3
2-Phenyl), 161.82 (d, JC,F = 1.1 Hz, CO), 178.90 (CS);
19F NMR (564.62 MHz, CDCl3):
d
ꢁ111.7, (DMSO-d6):
d
ꢁ113.9;
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MS: m/z 268 [M]+ (33), 123 (100);
Anal. Calc for C12H13FN2O2S: C, 53.7; H, 4.9; N, 10.4; S 12.0.
Found: C, 53.7; H, 5.3; N, 10.3; S, 12.1.
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4.9. N-[Bis(2-hydroxyethyl)carbamothioyl]benzamide (8) [6]
Colorless crystals, mp 118–120 8C;
1H NMR (600.13 MHz, H,H-COSY, HMQC, HMBC, DMSO-d6):
d
3.70 (br, 2H, OCH2), 3.72 (br, 2H, NCH2), 3.77 (br, 2H, OCH2), 3.99
(br, 2H, NCH2), 4.87 (t, 1H, OH), 5.65 (br, 1H, OH), 7.51 (t, 2H, H-3,5-
Phenyl), 7.60 (t, 1H, H-4-Phenyl), 7.86 (d, 2H, H-2,6-Phenyl), 10.88
(s, 1H, NH);
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Chem. Eur. J. 5 (1999) 492–497;
13C (150.90 MHz, HMQC, HMBC, DMSO-d6):
d 54.98 (NCH2),
(b) I.G. Shenderovich, A.P. Burtsev, G.S. Denisov, N.S. Golubev, H.H. Limbach,
Magn. Reson. Chem. 39 (2001), S 18–29;
(c) P. Lorente, I.G. Shenderovich, N.S. Golubev, G.S. Denisov, G. Buntkowsky, H.H.
Limbach, Magn. Reson. Chem. 39 (2001), S 91–99;
55.09 (NCH2), 57.58 (OCH2), 59.23 (OCH2), 127.86 (C-2,6-Phenyl),
128.60 (C-3,5-Phenyl), 132.36 (C-4-Phenyl), 133.52 (C-1-Phenyl),
164.53 (CO), 181.15 (CS).
(d) I.G. Shenderovich, P.M. Tolstoy, N.S. Golubev, S.N. Smirnov, G.S. Denisov, H.H.
Limbach, J. Am. Chem. Soc. 125 (2003) 11710–11720.
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4.10. N-[Bis(2-hydroxyethyl)carbamothioyl]-2-fluorobenzamide (9)
Colorless crystals, mp 110–112 8C;
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