Synthesis and experimental study of through-space hydrogen-fluorine and carbon-fluorine spin-spin coupling in 4,5-substituted 1-acetyl-8-fluoronaphthalenes

Article abstract of DOI:10.1016/S1386-1425(99)00215-2

The synthesis and NMR study (¹H, ¹³C, and ¹⁹F) of a complete series of 4,5-substituted 1-acetyl-8-fluoronaphthalenes are reported. This data revealed a ⁶J(H,F) and a ⁵J(C,F) through space coupling between the fluorine and the methyl on the acetyl group (¹H and ¹³C). The magnitude of this coupling constant changes depending on the nature of the substituent at C-4, the internuclear distance, and the solvent.

Full text of DOI:10.1016/S1386-1425(99)00215-2

Spectrochimica Acta Part A 56 (2000) 1167–1178
www.elsevier.nl/locate/saa
Synthesis and experimental study of through-space
hydrogen–fluorine and carbon–fluorine spin–spin coupling
in 4,5-substituted 1-acetyl-8-fluoronaphthalenes
Saul Jaime-Figueroa a,*, Lilia J. Kurz a, Yanzhou Liu a, Raymundo Cruz b
a Medicinal Chemistry Department, Neurobiology Business Unit, Roche Bioscience, 3401 Hill6iew A6enue, Palo Alto,
CA 94303, USA
b Instituto de Qu´ımica UNAM, Circuito Exterior C.U., D.F. 04510 Mexico
Received 28 April 1999; received in revised form 16 August 1999; accepted 13 September 1999
Abstract
The synthesis and NMR study (1H, 13C, and 19F) of a complete series of 4,5-substituted 1-acetyl-8-fluoronaphthale-
6
5
nes are reported. This data revealed a J(H,F) and a J(C,F) through space coupling between the fluorine and the
methyl on the acetyl group (1H and 13C). The magnitude of this coupling constant changes depending on the nature
of the substituent at C-4, the internuclear distance, and the solvent. © 2000 Elsevier Science B.V. All rights reserved.
Keywords: 1H NMR; 13C NMR; 19F NMR; Through-space coupling; Long range spin–spin coupling; Acetylfluoronaphthalenes
series, attracted our attention because of the
strong coupling of the fluorine atom at C-8 with
both the hydrogens and the carbon of the acetyl
moiety. A literature search revealed that 1-acetyl-
1. Introduction
Long range hydrogen–fluorine (H–F) and car-
bon–fluorine (C–F) NMR spin–spin couplings
have been the object of numerous studies. Never-
theless there still is considerable discussion and
controversy regarding the nature of the coupling
mechanism [1–12]. In connection with one of our
medicinal chemistry programs, we recently syn-
thesized a series of fluoronaphthalenes. The 1H
and 13C NMR spectra of 1-acetyl-4,8-difl-
uoronaphthalene (1a) (Fig. 1), one member of this
8-fluoronaphthalene (16 ) had been the subject of
both experimental and theoretical NMR studies
[1–5]. In these studies it was demonstrated that
these 5J(F, C) and 6J(H, F) couplings are likely to
be transmitted predominantly via a through-space
mechanism. As a consequence we synthesized sev-
eral 4-substituted-1-acetyl-8-fluoronaphthalenes
wherein the electronic nature of the substituent
was varied in a rational manner, and measured
the long range H–F and C–F NMR coupling
constants for these compounds (Schemes 1 and 2).
We also synthesized and studied by NMR a well
* Corresponding author. Tel.: +1-650-852-1875; fax: +1-
650-852-1555.
E-mail address: saul.jaime@roche.com (S. Jaime-Figueroa)
1386-1425/00/$ - see front matter © 2000 Elsevier Science B.V. All rights reserved.
PII: S1386-1425(99)00215-2

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S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
Fig. 1. 1H NMR of 1a in benzene (C6D6) recorded at 25°C.
defined series of 4,5-disubstituted-1-acetyl-8-
fluoronaphthalenes where the internuclear dis-
tance was varied (F, –CH3) (Scheme 3). The
synthesis and the experimental NMR studies of
these substances constitute the subject of this
paper.
NaOMe, NaSMe and NaN3 produced (1b) (1c)
and (1f), respectively. The sulfide (1c) and the
azide (1f) were converted into the sulfoxide (1d),
sulfone (1e) and the amine (1g) by standard tech-
niques (Section 3). The iminophosphorane (1h)
was obtained from (1f) and triphenylphosphine
(Scheme 1).
2. Results and discussion
2.1. 1-Acetyl-8-fluoronaphthalene and
4-substituted congeners
2.1.1. Synthesis
A literature search revealed that only the syn-
thesis of 1-acetyl-8-fluoronaphthalene (16 ) had
been reported. None of the other compounds of
the series described herein were known. Adcock
et. al. [1–3] and Contreras et al. [4,5] had synthe-
sized (16 ) using different synthetic pathways. We
prepared this substance more efficiently (30%
overall) from commercially available 1-bromo-8-
hydroxymethylnaphthalene (2
sequence shown in Scheme 2. The synthesis of the
4-substituted analogs of (1) commenced with 1,5-
difluoronaphthalene (5) [13–16]. Acetylation of
(5) under Friedel-Crafts conditions gave 1-acetyl-
4,8-difluoronaphthalene (1a), which served as the
precursor of the 4-substituted congeners of (1).
Thus, displacement of the 4-fluoro group with
6 ) via the five step
6
6
6
6
Scheme 1.

S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
1169
Table 1
Magnitude (Hz) of coupling constant for compounds 16 –1h
a
G
|
J(C, F)
J(H, F)
NOEb (%)
6.75
1h –N=
PPh3
–
10.97
4.82
1g –NH2
1b –OCH3 −0.27
1c –SCH3
1f –N3
1a –F
−0.66
10.05
9.88
9.50
9.48
9.06
8.95
8.28
4.32
4.15
3.94
3.82
3.64
3.40
3.15
5.18
5.21
4.48
3.77
8.18
2.87
2.50
0.00
+0.15
+0.06
0.00
Scheme 2. (a) TBSC1, Et3N, 4-DMAP, CH2Cl2. (b) 1.-nBuLi,
−78°; 2. −NFSI, −78° –r.t., THF. (c) Swern oxidation. (d)
MeLi, −78°, THF. (e) Swern oxidation.
1
6
–H
1d –
SOCH3
1e –
SO2CH3
+0.49
+0.72
8.45
3.20
5.07
a |(para) of Hammet from the literature [17].
b Observed NOEs in the fluorine nucleus, by irradiation of
the hydrogens in the methyl group
Table 2
Solvent and temperature effect on the coupling constant (Hz)
in 1a
Solvent
ma
6J(H, F)
5J(C, F)
Scheme 3.
DMSO-d6
DMF-d7
49.0
36.7
36.2
20.7
8.9
2.51
2.56
2.83
2.86
3.29
3.64
3.36
6.78
7.24
7.61
7.81
8.53
9.06
8.68
2.1.2. NMR analysis
A complete NMR study of the 4-substituted-1-
acetyl-8-fluoronaphthalenes showed that the cou-
pling constant J(F, C) and J(H, F) is sensitive
to the nature of the substituent at C-4. It is clear
that when the substituent is an electron donating
MeCN-d3
Acetone-d6
CH2Cl2-d2
CHCl3-d1
Benzene-d6
4.7
2.2
5
6
a m=Dielectric constant [18].

1170
S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
conformer has a similar dihedral angle (69°), that
where the oxygen is ‘anti’ to the fluorine atom at
C-8 (Fig. 3). Considering the observed NOE re-
sults (Table 1) between F/–CH3, we can assume
that the lowest energy conformer in solution is
similar to that in the solid state and that it is the
product of both steric and coulombic forces of
repulsion between the oxygen and the fluorine
nuclei. It is reasonable that any change in the
electronic density of the carbonyl group by a
substituent or solvent would change the internu-
clear (F, –CH3) distance resulting in a change in
magnitude of the coupling constant.
2.2.
4,5-Disubstituted-1-acetyl-8-fluoronaphthalenes
2.2.1. Synthesis
We synthesized a number of acetyl-fluoronaph-
thalenes, where the internuclear distance (F,
–CH3) was varied systematically (Table 3). Gener-
ation of the lithio compound from 1-bromo-4,5-
Fig. 2. Plots of the coupling constants 5J(F, C), 6J(H, F) and
the dielectric constant of the NMR solvent for 1a.
dimethylnaphthalene (66 ) [19] (Scheme 3) and
n-butyllithium and subsequent reaction of this
species with N-fluorobenzenesulfonimide gave the
fluoronaphthalene (6b). Friedel-Crafts acetylation
of this substance gave 1-fluoro-4,5-dimethyl-8-
group, the coupling constant is larger than when
it is an electron withdrawing group. There is a
distinct but not linear correlation between the
(s-para) Hammett [17] constant and the magni-
tude of this coupling constant (Table 1). We
acetylnaphthalene (76 ). The commercially available
5-bromoacenaphthene (6a) was converted into
(6c), by the methodology used to prepare (6b).
Acetylation of (6c) afforded (7a) [20], a known
compound for which the synthesis is poorly de-
scribed. Oxidation of (7a) with DDQ produced
confirmed, as has been observed for (16 ) by Ad-
cock et el. [1], that the coupling constant was
solvent dependent (Table 2). Variation from a low
(CDCl3, m=4.7) to high (DMSO-d6, m=49.0)
dielectric constant solvents [18], produced sub-
stantial changes in the magnitudes of the through
the acenaphthylene (86 ) (Scheme 3).
5
6
space J(F, C) and J(H, F) for (1a) which corre-
late linearly to the solvent dielectric constant (Fig.
2). It is important to mention that we did not use
protic solvents in this study, in order to avoid
hydrogen bonding interactions with the carbonyl
group.
2.2.2. NMR analysis
Interestingly the analysis of the NMR data in
all of these compounds (1), (7), (7a), (8) and (8a),
6
6
6
showed a clear dependence of the coupling con-
stant on the internuclear distance between the
fluorine and the methyl group in the acetyl moiety
(Table 3). If we consider this distance as a func-
tion of the calculated peri-angle q1–8 (MM2,
Chem3Dpro 4.0, using the dihedral driver), it is
expected that an increase in the magnitude of the
peri-angle will increase the internuclear distance
and thus diminish the coupling constant.
The X-ray structure of (1a) (Fig. 3) shows a
dihedral angle of 65° between the plane of the
aromatic ring and that containing the carbonyl
moiety. Similarly, molecular mechanics calcula-
tions in (1a) (MM2, Chem3Dpro 4.0, using a
dihedral driver) predict that the lowest energy

S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
1171
Fig. 3. Left, experimental X-ray structure of 1a and experimental dihedral angle. Right, MM2-calculated structure for the lowest
energy rotational conformer of 1a and the theoretical dihedral angle.
Table 3
Relationship between peri-angle q1–8 (MM2 calculations) and the experimental coupling constants 5J(F, C), 6J(F, H)
q (°)
J(C, F) (Hz)
J(H, F) (Hz)
b
b
8aa
125.29
131.02
130.55
123.62
120.35
8
6
7.90
8.73
8.95
9.92
2.78
3.20
3.40
4.13
7a
1
6
7
6
a NMR data from the literature [23].
b No coupling was detected.

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S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
3. Experimental
BDMSi), 0.89 (s 9H, t-BDMSi), 5.71 (s, 2H,
–CH2OSi), 7.21 (dd, J=8.2, 7.4 Hz, 1H, H-3),
7.48 (dd, J=8.2, 7.3 Hz, 1H, H-6), 7.72 (apparent
d, J1=8.2, Hz, 1H, H-5), 7.79 (dd, J=8.2, 1.3
Hz, 1H, H-4), 7.80 (dd, J=7.4, 1.3 Hz, 1H, H-2),
7.72–7.69 (ddd, J=7.3, 1.5, 1.4 Hz, 1H, H-7);
MS (m/z, % rel int) 352 (M++2)(5), 350 (M+
)(5), 295 (100), 219 (60), 140 (45). Calc. for
C17H23BrOSi (351.35): C, 58.11; H, 6.60. Found:
C, 58.38; H, 6.57%.
1
The H NMR and 13C NMR were measured on
a Bruker Avance DPX-300 NMR or on a Bruker
AMX-300 NMR spectrometers, operating at a
proton (1H) frequency of 300.13 MHz and carbon
(13C) frequency of 75.43 MHz, and a fluorine
(19F) frequency of 282.16 MHz. The experiments
were run in CDCl3 solutions with internal te-
tramethylsilane as the reference unless otherwise
noted. The 13C assignments were proven by con-
ventional NMR experiments (Table 4), including
the one-dimensional DEPT and selective nuclear
Overhauser effect (NOE), as well as the two-di-
mensional COSY, HMQC, HMBC and NOESY.
X-ray crystallography studies were performed on
a Siemens P4/PC. The mass spectra were recorded
on a Finnigan-MAT 8230 or on a VG ZabSpec-
QFPD spectrometers. The IR spectra were mea-
sured neat unless specified otherwise. The
following abbreviations are used: EtOAc, ethyl
acetate; DMF, dimethylformamide; THF, te-
trahydrofuran; NMP, 1-methyl-2-pyrrolidinone;
DMSO, dimethylsulfoxide; CFCl3, trichloro-
fluoromethane; PhCF3, trifluorotoluene; mCPBA,
m-chloroperbenzoic acid; and DDQ, 2,3-dichloro-
5,6-dicyano-1,4-benzoquinone.
3.2. 1-Fluoro-8-hydroxymethylnaphthalene (3a)
To a solution of (36 ) (350 mg, 1 mmol) in 20 ml
of THF at –78°C was added n-buthyllithium (1
N, 1 ml, 1 mmol). The reaction was stirred for 30
min. at the same temperature, and then N-
fluorobenzenesulphonimide (315 mg, 1 mmol) in
20 ml of THF was added slowly. The reaction was
warmed to room temperature and stirred 12 h.
Then the mixture was poured into water (50 ml),
was extracted with hexane (3×50 ml), dried
(Na2SO4), and evaporated under vacuum. The
residue was diluted with 10 ml of a solution of
acetic acid/THF/H2O (50:25:25) and stirred for 12
h at 60°C. The solution was evaporated to dryness
and purified by column chromatography (hex-
ane:EtOAc, 80:20, SiO2) to give 82 mg (47% yield)
of (3a) as a white solid: m.p. 78–80°C (sublimes
3.1. 1-Bromo-8-(t-butyldimethyl-silyloxy)methyl-
naphthalene (36 )
at 60°C/0.5 mmHg); IR (neat) 3256, 806 cm−1
;
1H NMR (CDCl3) l 2.29 (bs, 1H, –OH), 5.18 (d,
J=3.3 Hz, 2H, CH2OH), 7.17 (ddd, J=13.8, 7.7,
1.2 Hz, 1H, H-2), 7.39 (td, J=8.1, 7.7, 5.2 Hz,
1H, H-3), 7.46 (dd, J=8.2, 7.1 Hz, 1H, H-6), 7.59
(dd, J=8.2, 1.1 Hz, 1H, H-7), 7.65 (dd, J=8.2,
1.1 Hz, 1H, H-4), 7.80 (apparent d, J=7.1 Hz,
1H, H-5); 13C NMR (CDCl3) l 65.22 (JC-F=13.6
Hz), 111.37 (JC-F=23.6 Hz), 121.19 (JC-F=14
Hz), 124.92 (JC-F=3.8 Hz), 125.62 (JC-F=9.3
Hz), 126.47 (JC-F=1.7 Hz), 126.54, 127.97 (JC-
F=3.1 Hz), 135.34 (JC-F=5.5 Hz), 136.21 (JC-
F=5.8 Hz), 159.53 (JC-F=250.3 Hz); 19F NMR
(CDCl3, PhCF3 as external reference), l −52.26;
MS (m/z, % rel int) 176 (M+)(44), 147 (100), 159
(15). Calc. for C11H9FO (176.19): C, 74.99; H,
5.15. Found: C, 75.06; H, 5.11%.
To a solution of 1-bromo-8-hydroxy-methyl-
naphtalene (237 mg, 1 mmol) (Maybridge Chemi-
cal) in methylene chloride[SJ1][SJ2] (10 ml) was
added t-butyldimethylsilyl chloride (t-BDMSiCl)
(181 mg, 1.2mmol), triethylamine (152 mg, 1.5
mmol), and 4-dimethylaminopyridine (4-DMAP)
(10 mg) at room temperature. The solution was
stirred for 8 h, then was washed with water (3×
20 ml), extracted with methylene chloride (3×20
ml), and evaporated under vacuum. The product
was isolated by column chromatography on silica
gel using hexane (100%) as eluent to give 336 mg
of product (3
0.04 mmHg; IR (neat) 2955, 1257, 1109, 775
cm−1 1H NMR (CDCl3) l 0.06 (s, 6H, t-
6 ) as an oil (95% yield): b.p. 118°C/
;

Table 4
13C chemical shiftsa(l) and J(C, F) coupling constantsb of 4-substituted 1-acetyl-8-fluoronaphthalenes recorded at 25°C in CDCl3
C-1
C-2
C-3
C-4
C-4a
C-5
C-6
C-7
C-8
C-8a
Carbonyl
Me–
Other
l
J(C,
l
J(C,
d
J(C,
l
J(C,
d
J(C,
l
J(C,
l
J(C,
l
J(C,
l
J(C,
l
J(C,
l
J(C,
l
J(C,
l
F)
F)
F)
F)
F)
F)
F)
F)
F)
F)
F)
F)
c
c
c
c
1
6
137.91
124.4
126.45
129.79
2.93 135.65 4.4
124.84 3.84
126.94 8.75
127.74 7.65
111.89 21.32
113.29 21.34
158.24 252.26 119.69 14.98
158.21 252.47 121.58 16.51
205.4
31.78
31.81
8.95
9.06
c
c
1a
134.32 6.71
125.22 9.07
110.29 20.66 159.65 255.7 126.08 17.94 117.73 5.88
204.25
/
1.33
5.23
5.38
4.21
4.77
5.10
c
1b
131.27
127.19 1.45
104.86 1.00 158.01
4.33 128.77 5.72 119.98 3.82
3.40 132.75 4.82 120.53 3.83
2.56 131.75 4.34 119.49 4.16
127.24 6.95
126.62 8.94
129.85 8.98
113.77 21.3
111.95 21.35
113.93 21.21
159.16 250.72 122.10 16.32
158.03 251.93 119.63 15.28
159.69 254.71 121.06 15.07
205.57
204.28
205.21
32.47
31.18
32.75
9.88
9.50
8.28
–
OMe,
57.19
c
c
c
c
c
1c
1d
134.35
124.83
121.83
139.10
–
SMe,
15.56
c
141.77 1.88
125.06
124.15 1.34 145.13
5
–
SOMe
,
(
44.40
c
c
c
1e
143.66
122.14
130.17 1.17 136.71
3.08 130.57 3.76 120.63 4.20
129.69 9.09
112.75 20.89
158.20 254.23 120.41 15.08
203.24
31.24
8.45
167
–
SO2M
e,
178
44.24
c
c
c
c
1f
132.26
122.62
111.91 1.41 136.64
c
4.64 126.16 5.09 117.93 3.96
127.40 5.58 119.70 3.76
125.00 8.69
127.85 9.07
123.94 8.82
110.9 21.16
114.55 21.89
111.76 21.67
155.79 251.77 118.78 16.12
160.96 251.48 123.48 15.70
158.09 251.15 121.50 12.69
202.04
206.55
204.29
29.39
9.4
c
c
1g
1h
130.37
129.38
111.10
146.92
*
33.42 10.05
30.64
c
c
c
125.22
127.65
112.92
151.62
3.74 133.71 5.28 121.85 2.94
23.99d
e
11.24d
10.97
a Chemical shifts in ppm. (CDCl3, relative to Me4Si).
b Coupling constants in Hz.
c No coupling constant was detected.
d J(C, P) coupling constant.
e See experimental for the other signals.

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S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
3.3. 1-Formyl-8-fluoronaphthalene (4
6
)
49–51°C (sublimes at 50°C/0.7 mmHg) (248 mg,
90% yield); IR (neat) 3422 cm−1 1H NMR
;
To a solution of DMSO (665 mg, 0.6 ml, 8.51
mmol) in 100 ml of methylene chloride was added
oxalyl chloride (721 mg, 0.48 ml, 5.67 mmol) at
−78°C. The reaction was stirred for 30 min at the
same temperature, and then the alcohol (3a) (500
mg, 2.86 mmol) was added into the reaction mix-
ture at −78°C, and it was stirred for 30 min at
−45°C. After that triethylamine (1.43 g, 1.97 ml,
14.19 mmol) was added slowly at −78°C. The
reaction was warmed to room temperature and
stirred for 30 min. The mixture was poured into
water (200 ml) and the product was extracted with
methylene chloride (3×100 ml). The product was
purified by column chromatography on silica gel
using hexane/EtOAc (80:20) as eluent to give 484
(CDCl3) l 1.58 (dd, J=6.3, 1.8 Hz, 3H, –CH3),
2.15 (bs, 1H, –OH), 5.88 (apparent q, 1H,
CH(OH)CH3), 7.15 (ddd, J=14.3, 7.7, 1.2 Hz,
1H, H-2), 7.37 (ddd, J=8.1, 8.0, 5.0 Hz, 1H,
H-3), 7.49 (dd, J=7.8, 7.3 Hz, 1H, H-6), 7.64
(dd, J=8.0, 1.2 Hz, 1H, H-4), 7.74 (apparent d,
J=7.8 Hz, 1H, H-7), 7.87 (d, J=7.3 Hz, 1H,
H-5); 13C NMR (CDCl3) l 25.69 (JC-F=2.1 Hz),
68.00 (JC-F=15.9 Hz), 111.57 (JC-F=24.3 Hz),
120.47 (JC-F=13.8 Hz), 122.91, 125.05 (JC-F=3.8
Hz), 125.37 (JC-F=9.3 Hz), 126.50 (JC-F=1.7
Hz), 127.43 (JC-F=2.9 Hz), 136.12 (JC-F=5.9
Hz), 141.57 (JC-F=6.7 Hz), 159.24 (JC-F=251.5
Hz); 19F NMR (CDCl3, PhCF3 as external refer-
ence), l −48.38; MS (m/z, % rel int) 190 (M+
)(85), 175 (100), 147 (90). Calc. for C12H11FO
(190.21): C, 75.77; H, 5.83. Found: C, 75.89; H,
5.68%.
mg (98% yield) of pure product (46 ) as a white
solid; m.p. 64–65°C (sublimes at 50°C/1 mmHg);
1
IR (neat) 1682 cm−1; H NMR (CDCl3) l 7.36
(ddd, J=13.3, 7.7, 1.1 Hz, 1H, H-7), 7.52 (ddd,
J=8.2, 7.5, 5 Hz, 1H, H-6), 7.62 (dd, J=8.2, 7.3
Hz, 1H, H-3), 7.76 (dd, J=8.2, 1.2 Hz, 1H, H-5),
8.10 (ddd, J=8.2, 2.1, 1.3 Hz, 1H, H-4), 8.24 (dd,
J=7.3, 1.3 Hz, 1H, H-2), 11.00 (d, J=2.7 Hz,
3.5. 1-Acetyl-8-fluoronaphthalene (16 )
To a solution of DMSO (266 mg, 0.24 ml, 3.4
mmol) in 40 ml of methylene chloride at −78°C
was added oxalyl chloride (288 mg, 0.195 ml, 2.27
mmol). The reaction mixture was stirred for 30
min at the same temperature. Then alcohol (4a)
(200 mg, 1.13 mmol) was added to the reaction
mixture at −78°C, which was stirred for 30 min.
at −45°C. After that, triethylamine (574 mg,
0.791 ml, 5.67 mmol) was added slowly at −
78°C. The reaction mixture was warmed to room
temperature and stirred for 30 min. The mixture
was poured into water (50 ml) and the product
was extracted with methylene chloride (3×50
ml). The product was purified by column chro-
matography on silica gel, using hexane/EtOAc
1H, CHO); 13C NMR (CDCl3) l 112.76 (JC-F
22.6 Hz), 121.12 (JC-F=15.9 Hz), 124.93 (JC-F
=
=
3.5 Hz), 125.84 (JC-F=1.5 Hz), 126.07 (JC-F=8.8
Hz), 128.32, 131.95 (JC-F=7.7 Hz), 133.64 (JC-
F=2.7 Hz), 135.44 (JC-F=6.6 Hz), 158.97 (JC-
F=252.4 Hz), 192.50 (JC-F=20.5 Hz); 19F NMR
(CDCl3, CFCl3 as external reference), l −108.1;
MS (m/z, % rel int) 174 (M+)(8), 173 (15) 146
(100). Calc. for C11H7FO (174.17): C, 75.86; H,
4.05. Found: C, 75.80; H, 3.97%.
3.4. 1-Fluoro-8-(1-hydroxyethyl)naphthalene (4a)
To a solution of (4
6
) (250 mg, 1.43 mmol) in
(90:10) as the eluent. The product (1
6 ) was ob-
THF (50 ml) was added methyllithium (0.98 ml,
1.58 mmol, 1.6M) at −78°C. After the addition
was completed the temperature was raised to 0°C,
and the reaction was stirred 30 min at the same
temperature. The mixture was poured into water
(100 ml), the product was extracted with Et2O
(3×100 ml) and purified by column chromatog-
raphy on silica gel (hexane:EtOAc, 80:20). The
alcohol (4a) was obtained as a white solid, m.p.
tained as an oil (78% yield); IR (neat) 1701 cm−1
;
1H NMR (CDCl3) l 2.62 (d, J=3.4 Hz, 3H,
–COMe), 7.23 (ddd, J=11.9, 7.7, 1.0 Hz, 1H,
H-7), 7.39 (dd, J=7.0, 1.1 Hz, 1H, H-2), 7.43-
7.54 (m, 2H, H-3,6), 7.70 (apparent d, J=8.25,
1H, H-4), 7.91 (dd, J=8.3, 1.0 Hz, 1H, H-5); 13C
NMR (CDCl3) (Table 4); 19F NMR (CDCl3,
CFCl3 as external reference), l −110.42; MS
(m/z, % rel int) 188 (M+)(34), 173 (100), 145 (65).

S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
1175
Calc. for C12H9FO (188.20): C, 76.58; H, 4.82.
Found: C, 76.25; H, 4.81%.
CFCl3 as external reference), l −109.61; MS
(m/z, % rel int) 218 (M+)(35), 203 (100), 175 (20).
Calc. for C13H11FO2 (218.22): C, 71.55; H, 5.01.
Found: C, 71.41; H, 4.86%.
3.6. 1-Acetyl-4,8-difluoronaphthalene (1a)
To a solution of 1,5-difluoronaphthalene (56 )
3.8. 1-Acetyl-8-fluoro-4-thiomethoxynaphthalene
(1c)
[13–16] (1.64 g, 10 mmol) in DCE (50 ml) was
added at 0°C AlCl3 (2.66 g, 20 mmol). At the
same temperature was added slowly over 20 min.
Ac2O (1.02 g, 0.94 ml, 10 mmol). The reaction
mixture was stirred 30 min and was then poured
into ice water/HCl (10%). The product was ex-
tracted with CH2Cl2 (2×100 ml). The organic
phase was dried (Na2SO4) and evaporated. The
reaction mixture was purified by column chro-
matography on silica gel using pentane:Et2O
(90:10) as eluent. The pure product (1a) was ob-
tained (1.5 g, 73% yield) as a white solid m.p.
To a solution of (1a) (50 mg, 0.24 mmol) in
DMSO (1 ml) was added sodium thiomethoxide
(17 mg, 0.24 mmol) at room temperature. The
solution was stirred 1 h at the same temperature
after which the reaction mixture was diluted with
20 ml of Et2O:hexane (50:50). The organic phase
was washed with water (3×20 ml) and dried over
sodium sulfate. Evaporation of solvents gave a
white solid (93% yield) (1c) m.p. 72–73°C (sub-
1
limes 60°C/0.4 mmHg); IR (neat) 1697 cm−1; H
46–47°C (hexane); IR (neat) 1703 cm−1 1H
;
NMR (CDCl3) l 2.59 (d, J=3.94 Hz, 3H, –
COMe), 2.60 (s,3H, –SMe), 7.27 (ddd, J=11.9,
7.7, 0.9 Hz, 1H, H-7), 7.32 (d, J=7.6 Hz, 1H,
H-3), 7.34 (d, J=7.6 Hz, 1H, H-2), 7.52 (ddd,
J=8.5, 7.7, 5.5 Hz, 1H, H-6), 8.09 (dd, J=8.5,
0.9 Hz, 1H, H-5); 13C NMR (CDCl3)) (Table 4);
19F NMR (CDCl3, CFCl3 as external reference), l
−108.45; MS (m/z, % rel int) 234 (M+)(50), 219
(100). Calc. for C13H11FOS (234.29): C, 66.64; H,
4.73. Found: C, 66.57; H, 4.68%.
NMR (CDCl3) l 2.60 (d, J=3.64 Hz, 3H, -
COMe), 7.18 (dd, J=9.9, 7.9, 1H, H-3), 7.28 (m,
1H, H-7), 7.36 (dd, J=7.9, 5.2 Hz, 1H, H-2), 7.52
(ddd, J=8.4, 7.7, 5.1 Hz, 1H, H-6), 7.92 (appar-
ent d, J=8.4 Hz, 1H, H-5); 13C NMR (CDCl3))
(see Table 4); 19F NMR (CDCl3, CFCl3 as exter-
nal reference), l −109.42, −118.23; MS (m/z, %
rel int) 206 (M+)(32), 191 (100), 163 (54). Calc.
for C12H8F2O (206.19): C, 69.90; H, 3.91. Found:
C, 70.11; H, 3.90%.
3.7. 1-Acetyl-8-fluoro-4-methoxynaphthalene (1b)
3.9. 1-Acetyl-8-fluoro-4-methansulfinylnaphtha-
lene (1d)
A solution of 1-acetyl-4,8-difluoronaphthalene
(1a) (50 mg, 0.24 mmol) in NaOMe (2 ml, 1
mmol, solution 0.5M in methanol) was heated at
reflux for 8 h. The reaction mixture was poured
into HCl (1 N). The product was extracted with
CH2Cl2 (20 ml). After drying (Na2SO4) and evap-
oration, the residue was purified by column chro-
matography on silica gel (hexane:EtOAc, 90:10),
to obtain the pure product (1b) as an oil (48 mg,
To a solution of (1c) (57 mg, 0.24 mmol) in
methylene chloride (15 ml) at 0°C was added
mCPBA (50 mg at 80%, 0.24 mmol). The reaction
mixture was stirred at 0°C. The reaction was
washed with aqueous Na2S2O7 (10%) (20 ml). The
organic phase was washed with aqueous solution
of sodium bicarbonate (20 ml) and dried with
sodium sulfate. After evaporation the crude mix-
ture was purified by column chromatography on
silica gel using EtOAc (100%). The pure product
(1d) (56 mg, 93% yield) was obtained as a white
92% yield); IR (neat) 1695 cm−1 1H NMR
;
(CDCl3) l 2.58 (d, J=4.15 Hz, 3H, –COMe),
4.02 (s,3H, –OMe), 6.81 (d, J=7.9, 1H, H-3),
7.25 (ddd, J=12.1, 7.7, 1.1 Hz, 1H, H-7), 7.39 (d,
J=7.9, 1H, H-2), 7.45 (ddd, J=8.0, 7.7, 5.3 Hz,
1H, H-6), 8.11 (dd, J=8.0, 1.0 Hz, 1H, H-5); 13C
NMR (CDCl3)) (see Table 4); 19F NMR (CDCl3,
solid m.p.108–109°C; IR (KBr) 1701, 1059 cm−1
;
1H NMR (CDCl3) l 2.66 (d, J=3.15 Hz, 3H,
–COCH3), 2.84 (s,3H, –SOMe), 7.34 (ddd, J=
11.8, 7.7, 0.9 Hz, 1H, H-7), 7.58 (d, J=7.4, 1H,

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S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
H-2), 7.62 (m, 1H, H-6), 7.75 (dd, J=8.4, 0.9 Hz,
1H, H-5), 8.25 (d, J=7.4 Hz, 1H, H-3); 13C
NMR (CDCl3) (Table 4); 19F NMR (CDCl3,
CFCl3 as external reference), l −106.56; MS
(m/z, % rel int) 250 (M+)(100), 207 (95). Calc. for
C13H11FO2S (250.29): C, 62.38; H, 4.43. Found:
C, 62.17; H, 4.39%.
to give (1f) (35 mg, 64%) as a white solid; m.p.
64–66°C (t-butylmethylether: hexane); IR (neat)
1
2120, 1703 cm−1; H NMR (CDCl3) l 2.60 (d,
J=3.82 Hz, 3H, –CH3), 7.26 (d, J=7.6 Hz, 1H,
H-2), 7.27 (m, 1H, H-7), 7.40 (d, J=7.6 Hz, 1H,
H-3), 7.48 (ddd, J=8.5, 7.7, 5.3 Hz, 1H, H-6),
7.96 (dd, J=8.5, 0.9 Hz, 1H, H-5); 13C NMR
(CDCl3) (Table 4); 19F NMR (CDCl3, CFCl3 as
external reference) l −109.30; MS (m/z, % rel
int) 229 (M+), 201 (100). Calc. for C12H8FON3
(229.21): C, 62.88; H, 3.52; N,18.33. Found: C,
63.18; H, 3.48, N, 18.03%.
3.10. 1-Acetyl-8-fluoro-4-methansulfonylnaphtha-
lene (1e)
To a solution of (1d) (47 mg, 0.18 mmol) in
methylene chloride (4 ml) was added mCPBA (40
mg at 80%, 0.18 mmol) at room temperature. The
reaction mixture was stirred for 6 h. at room
temperature. The reaction was washed with
aqueous Na2S2O7 (10%) (20 ml). The organic
phase was washed with aqueous solution of
sodium bicarbonate (20 ml) and dried with
sodium sulfate. After evaporation the crude mix-
ture was purified by column chromatography on
silica gel using hexane: EtOAc (70:30) as the
eluent, to give (1e) (48 mg, 96% yield) as a white
solid m.p. 144–145°C (CH2Cl2/tBu(Me)O); IR
3.12. 1-Acetyl-8-fluoro-4-aminonaphthalene (1g)
The mixture of (1f) (50 mg, 0.21 mmol), Pd/C
10% (50 mg), and EtOAc (5 ml) was stirred under
H2 atmosphere for 6 h. The suspension was
filtered through a celite pad. The filtrate was
evaporated under vacuum and purified by column
chromatography on silica gel using hexane:
EtOAc (70:30) as eluent. The pure product (1g)
(40 mg, 90% yield) was obtained as a white solid
m.p. 191–192°C (CH2Cl2–hexane); IR (neat)
1
(neat) 1709, 1143, 1307 cm−1; H NMR (CDCl3)
1
l 2.65 (d, J=3.20 Hz, 3H, -COCH3), 3.22 (s, 3H,
–SO2Me), 7.40 (dd, J=11.5, 7.8 Hz, 1H, H-7),
7.48 (d, J=7.5 Hz, 1H, H-2), 7.77 (ddd, J=8.7,
8.1, 5.6 Hz, 1H, H-6), 8.41 (d, J=7.5, Hz, 1H,
H-3), 8.63 (d, J=8.7 Hz, 1H, H-5); 13C NMR
(CDCl3) (Table 4); 19F NMR (CDCl3, PhCF3 as
external reference) l −43.32; MS (m/z, % rel int)
266 (M+), 251 (100), 144 (52). Calc. for
C13H11FO3S(266.29): C, 58.64; H, 4.16. Found: C,
58.65; H, 4.11%.
3468, 3370, 1656 cm−1; H NMR (CDCl3) l 2.56
(d, J=4.32 Hz, 3H, –CH3), 4.44 (br s, 3H,
–NH2), 6.72 (d, J=7.7 Hz, 1H, H-3), 7.21 (ddd,
J=12.0, 7.7, 0.9 Hz, 1H, H-7), 7.32 (d, J=7.7,
1H, H-2), 7.41 (ddd, J=8.4, 7.7, 5.3 Hz, 1H,
H-6), 7.51 (dd, J=8.4, 0.9 Hz, 1H, H-5); 13C
NMR (CDCl3) (Table 4); 19F NMR (CD2Cl2,
CFCl3 as external reference) l −106.24; MS (m/
z, % rel int) 203 (M+)(55), 188 (100); HRMS calc.
for C12H10FNO (M+) 203.074642, found
203.074574.
3.11. 1-Acetyl-8-fluoro-4-azidonaphthalene (1f)
To a solution of (1a) (50 mg, 0.24 mmol) in
DMSO (1 ml) was added sodium azide (160 mg,
2.4 mmol). The reaction was stirred for 12 h at
100°C. The reaction was poured into water (20
ml) and the product was extracted with Et2O:
hexane (1:1) (3×20 ml). The organic layer was
washed with water (3×20 ml), dried (sodium
sulfate), and evaporated under vacuum. The
residue was purified by column chromatography
on silica gel using hexane:EtOAc (70:30) as eluent
3.13. 1-Acetyl-8-fluoro-4-(triphenylphosphoram-
idyl)naphthalene (1h)
To a solution of (1f) (229 mg, 1 mmol) in THF
(20 ml) was added triphenylphosphine (262 mg, 1
mmol) at room temperature. The reaction was
stirred for 12 h. After the evaporation of solvent,
the product was purified by column chromatogra-
phy on silica gel (hexane:EtOAc, 80:20). The pure
product (1h) (403 mg, 87% yield) was obtained as

S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
1177
a foam; IR 3443, 1410 cm−1; 1H NMR (CDCl3) l
3.16. 5-Fluoroacenaphthene (6c) [21,22]
2.50 (d, J=4.82 Hz, 3H, –CH3), 6.31 (dd, J=
7.9, 1.2 Hz, 1H, H-3), 7.10 (d, J=7.9 Hz, 1H,
H-2), 7.19 (ddd, J=12.3, 7.6, 1.1 Hz, 1H, H-7),
7.37–7.59 (m, 10H, H-6, –PPh3), 7.77–7.85 (m,
6H, –PPh3); 13C NMR (CDCl3)) (Table 4); 19F
NMR (CDCl3, CFCl3 as external reference), l
−109.7; MS (m/z, % rel int) 463 (M+)(100), 448
(80). Calc. for C30H23FNOP.1H2O: C, 74.83; H,
5.23; N, 2.91. Found: C, 75.03; H, 5.23, N, 2.99%.
This compound was prepared using 5-bromo-
acenaphthene (6a) (Aldrich) as a starting material
and following the same preparation procedure
described for 3a. Compound 6c was obtained as a
1
solid at 53% yield: H NMR (CDCl3) l 3.31–3.45
(m, 4H, –CH2–CH2–), 7.04–7.16 (m, 2H, H-4,3),
7.30 (apparent d, J=6.9 Hz, 1H, H-8), 7.47 (dd,
J=8.2, 6.9 Hz, 1H, H-7), 7.72 (dd, J=8.2, 0.8
Hz, 1H, H-6).
3.14. 1,5-difluoronaphthalene (56 ) [13–16]
3.17. 1-Acetyl-8-fluoro-4,5-dimethylnaphthalene
(76 )
This compound was prepared as described by
Schiemann et al. [16], [SJ3][SJ4]m.p. 67–68°C
(sublimes at 40°C/0.7 mmHg) (38% yield); IR
This compound was obtained as an oil, in 59%
yield using the method described for the prepara-
1
(neat) 772, 920, 1404 cm−1; H NMR (CDCl3) l
tion of 1a and as starting material 6b: IR (neat)
7.19 (ddd, J=10.3, 7.7, 0.8 Hz, 2H, H-2,6),
7.43(ddd, J=8.6, 7.7, 4.7 Hz, 2H, H-3,7), 7.86
(apparent d, J=8.6 Hz, 2H, H-4,8); 13C NMR
(CDCl3) l 110.52, 116.52, 125.43, 126.13, 158.58
(JC-F=251.9 Hz); 19F NMR (CDCl3, CFCl3 as
external reference), l −125.99; MS (m/z, % rel
int) 164 (M+)(100). Calc. for C10H6F2 (164.15): C,
73.17; H, 3.68. Found: C, 73.34; H, 3.61%.
1244, 1701, 2976 cm−1; H NMR (CDCl3) l 2.34
1
(d, J=4.13 Hz, 3H, –COMe), 2.88 (s, 3H, –Me),
2.91 (s, 3H, –Me), 7.04 (dd, J=11.3, 7.9 Hz, 1H,
H-7), 7.19 (d, J=7.2 Hz, 1H, H-2), 7.21 (dd,
J=7.9, 6.9 Hz, 1H, H-6), 7.28 (d, J=7.2 Hz, 1H,
H-3); 13C NMR (CDCl3) l 25.78, 25.92, 31.33(JC-
F=9.92 Hz), 123.38, 129.51(JC-F=8.7 Hz),
129.54(JC-F=1.2 Hz), 131.96(JC-F=4.1 Hz),
134.41(JC-F=3.5 Hz), 136.62, 137.63(JC-F=2.9
Hz), 156.92(JC-F=248.4 Hz), 205.23(JC-F=2.3
Hz); 19F NMR (CDCl3, PhCF3 as external refer-
ence), l −47.24; MS (m/z, % rel int) 216 (M+
)(60), 201 (100). Calc. for C14H15FO (216.25): C,
77.76; H, 6.06. Found: C, 77.91; H, 5.98%.
3.15. 1-Fluoro-4,5-dimethylnaphthalene (6b)
This compound was prepared using 1-bromo-
4,5-dimethylnaphthalene (66 ) [19] as a starting ma-
terial, following the same preparation procedure
for (3a). Compound (6b) was obtained as a solid
at 47% yield; m.p. 78–79°C (sublimes at 45°C/0.3
3.18. 5-Acetyl-6-fluoroacenaphthene (7a) [20,21]
mmHg); IR (neat) 794, 1415, 2932 cm−1 1H
;
NMR (CDCl3) l 2.88 (s, 3H, –Me), 2.92 (s, 3H,
–Me), 6.97 (dd, J=9.9, 7.7 Hz, 1H, H-2), 7.15
(dd, J=7.8, 6.2 Hz, 1H, H-3), 7.26–7.38 (m, 2H,
H-6,7), 7.80 (apparent d, J=8.1 Hz, 1H, H-8);
This compound was obtained as an oil at 31%
yield using the method described for the prepara-
tion of 1a and using as starting material 5-
fluoroacenaphthene (6c): IR (neat) 819, 841, 1693,
1
13C NMR (CDCl3) l 25.56, 25.66, 108.31 (JC-F
19.7 Hz), 119.51 (JC-F=8.6 Hz), 125.44 (JC-F
=
=
2924 cm−1; H NMR (CDCl3) l 2.63 (d, J=3.20
Hz, 3H, –COMe), 3.33-3.43 (m, 4H, –CH2–
CH2), 7.13–7.28 (m, 3H, H-3,7,8), 7.49 (d, J=
7.23 Hz, 1H, H-4); 13C NMR (CDCl3) l 31.36,
32.49 (JC-F=8.73 Hz), 32.63, 115.40 (JC-F=22.4
Hz), 115.41 (JC-F=17.2 Hz), 121 (JC-F=1.4 Hz),
121.59 (JC-F=7.8 Hz), 129.32, 134.76 (JC-F=3.8
Hz), 142.71 (JC-F=6.6 Hz) 143.47 (JC-F=3.51
Hz), 150.68 (JC-F=2.8 Hz), 157.02 (JC-F=250.4
1.9 Hz), 128.28 (JC-F=8.4 Hz), 131.15 (JC-F=4.4
Hz), 133.96 (JC-F=3.2 Hz), 126.54, 135.60 (JC-
F=2.7 Hz), 157.86 (JC-F=248.4 Hz); 19F NMR
(CDCl3, PhCF3 as external reference), l −61.37;
MS (m/z, % rel int) 174 (M+)(100), 159 (80).
Calc. for C11H9FO (174.21): C, 82.73; H, 6.36.
Found: C, 82.95; H, 6.27%.

1178
S. Jaime-Figueroa et al. / Spectrochimica Acta Part A 56 (2000) 1167–1178
Hz), 205.54; 19F NMR (CDCl3, PhCF3 as external
reference), l −54.17; MS (m/z, % rel int) 214
(M+)(55), 199 (100). HRMS calc. for C14H11FO
(M+) 214.079393, found 214.079311. An insepa-
rable mixture (1:1) of 3-acetyl-5-fluoroacenaph-
thene and 3-acetyl-6-fluoroacenaphthene was also
obtained in 48% yield.
distance (Table 3). All of these experimental data
are consistent with the observation by Adcock et.
al. and Contreras et. al. [1–5] and confirm that
this magnetic phenomenon occurs mainly by the
through space mechanism.
References
[1] W. Adcock, D.G. Matthews, S.Q.A Risvi, Aust. J. Chem.
24 (1971) 1829–1838.
3.19. 5-Acetyl-6-fluoroacenaphthylene (86 )
[2] W. Adcock, S.Q.A Risvi, Aust. J. Chem. 26 (1973) 2659–
2663.
[3] W. Adcock, M. Bullpitt, W. Kitching, J. Org. Chem. 42
(1977) 2411–2418.
[4] R.H. Contreras, I.D. Rae, A. Staffa, et al., Aust. J.
Chem. 40 (1987) 1923–1940.
[5] R.H. Contreras, D.J. Keavy, E.R. Olson, et al., Magn.
Res. Chem. 29 (1991) 422–432.
[6] L.C. Hsee, D.J. Sardella, Magn. Reson. Chem. 28 (1990)
688–692.
[7] G.W. Gribble, E.R. Olson, J. Org. Chem. 58 (1993)
1631–1634.
[8] J.W. Lyga, R.N. Henrie, G.A. Meier, R.W. Creekmore,
R.M. Patera, Magn. Reson. Chem. 31 (1993) 323–328.
[9] J.J. Parlow, C.R. Jones, D.M. Schnur, Heterocycl. Chem.
33 (1996) 1835–1838.
[10] A. Mele, G. Salani, F. Viani, P. Bravo, Magn. Reson.
Chem. 35 (1997) 168–174.
[11] R.H. Contreras, I.D. Rae, J.A. Weigold, G. Yamamoto,
Magn. Reson. Chem. 30 (1992) 1047–1050.
[12] R.H. Contreras, I.D. Rae, J.A. Weigold, R.R. Biekofsky,
Magn. Reson. Chem. 31 (1993) 836–840.
[13] A.G. Schultz, G. Zihong, Tetrahedron Lett. 36 (5) (1995)
659–662.
[14] W. Adcock, J. Alste, S.Q.A. Risvi, M. Aurangzeb, J. Am.
Chem. Soc. 98 (7) (1976) 1701–1711.
[15] W. Adcock, D. Doddrell, M. Barfield, M. Aurangzeb, D.
Jordan, J. Chem. Soc. Perkin II, (1976) 402–412.
[16] G. Schiemann, W. Gueffray, W. Winkelmuller, Justus
Liebigs Ann. Chem. 487 (1931) 270.
A solution of 5-acetyl-6-fluoroacenaphthene
(7a) (56 mg, 0.26 mmol) and DDQ (178 mg, 0.78
mmol) in benzene (10 ml) was boiled under reflux
for 24 h. After evaporation, the crude mixture
was purified by column chromatography on silica
gel using hexane:EtOAc (90:10). The pure product
(86
) (26 mg, 45% yield) was obtained as an oil: IR
(neat) 843, 1238, 1442, 1697, 3010 cm−1
;
1H
NMR (CDCl3) l 2.69 (d, J=2.78 Hz, 3H, –
COMe), 6.99 (d, J=5.3 Hz, 1H, H-2), 7.07 (d,
J=5.3 Hz, 1H, H-1), 7.17 (dd, J=12.1, 7.5 Hz,
1H, H-7) 7.55 (d, J=7.1 Hz, 1H, H-3), 7.57(dd,
J=7.5, 3.8 Hz, 1H, H-8), 7.66 (d, J=7.1 Hz, 1H,
H-4); 13C NMR (CDCl3) l 32.07 (JC-F=7.90 Hz),
113.34 (JC-F=23.2 Hz), 115.47 (JC-F=17.39 Hz),
123.94, 125.54 (JC-F=8.6 Hz), 127, 128.81 (JC-
F=4.6 Hz), 129.85 (JC-F=6.3 Hz), 131.23,
135.91 (JC-F=4.0 Hz), 137.36 (JC-F=2.8 Hz),
141.61 (JC-F=2.1 Hz), 159.35 (JC-F=260.9 Hz),
203.64; 19F NMR (CDCl3, CFCl3 as external ref-
erence), l −109.8; MS (m/z, % rel int) 212
(M+)(55), 197 (100), 169 (60). HRMS calc. for
C14H9FO (M+) 212.063743, found 212.063549.
[17] C. Hansch, A. Leo, Substituent Constants for Correlation
Analysis in Chemistry and Biology, Wiley, New York,
1979, pp. 49–52.
4. Conclusions
[18] A.J. Gordon, R.A. Ford, The Chemist, Wiley, s Compan-
ion’. New York, 1972, pp. 3–13.
[19] W.J. Mitchell, R.D. Topsom, J. Vaughan, J. Chem. Soc.,
(1962) 2526–2528.
[20] L.W. Deady, P.M. Gray, R.D. Topsom, J. Org. Chem. 37
(21) (1972) 3335–3338.
[21] L.W. Deady, P.M. Gray, R.D. Topsom, Appl. Spectrosc.
28 (6) (1974) 552–554.
In summary, 12 new acetylfluoronaphthalenes
were synthesized and studied by NMR spectrome-
try. We can draw the following conclusions re-
garding 5J(F,C) and 6J(H,F) coupling in the
1-acetyl-8-fluoronaphthalene system: (a) the cou-
pling is sensitive to the nature of the substituent
at C-4 (Table 1); (b) the magnitude of this con-
stant is solvent dependent (Table 2); (c) the cou-
pling constant is sensitive to the internuclear
[22] M.J.S. Dewar, J. Michl, Tetrahedron 26 (1970) 375–384.
[23] F.B. Mallory, E.D. Luzik Jr, C.W. Mallory, P.J. Carroll,
J. Org. Chem. 57 (1992) 366–367.
.