Photo-induced intramolecular arene-olefin meta-cycloaddition of 5-phenyl-fluorinated-pent-1-enes

Article abstract of DOI:10.1016/S0022-1139(99)00042-1

A series of fluorinated angular and linear triquinanes and their aza-analogues have been synthesized by photo-induced intramolecular meta-cycloaddition of 5-phenyl-fluorinated-pent-1-enes.

Full text of DOI:10.1016/S0022-1139(99)00042-1

Journal of Fluorine Chemistry 97 (1999) 149±156
Photo-induced intramolecular arene-ole®n meta-cycloaddition
of 5-phenyl-¯uorinated-pent-1-enes
Xiao-Chuan Guo, Qing-Yun Chen*
Laboratory of Organo¯uorine Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Lu, Shanghai 200032, China
Received 9 November 1998; received in revised form 17 December 1998; accepted 17 December 1998
Dedicated to Prof. Yoshiro Kabayashi on the occasion of his 75th birthday
Abstract
A series of ¯uorinated angular and linear triquinanes and their aza-analogues have been synthesized by photo-induced intramolecular
meta-cycloaddition of 5-phenyl-¯uorinated-pent-1-enes. # 1999 Elsevier Science S.A. All rights reserved.
Keywords: Fluorinated triquinanes; Intramolecular meta-cycloaddition; Photochemistry
1. Introduction
photochemistry of 5-phenyl-¯uorinated-pent-1-ene and its
aza-analogues.
The meta- or 1,3-photoaddition of ole®ns to arenes is
unique among the cycloaddition reactions. From the readily
available materials under mild conditions, it provides a
cycloadduct having three new rings and up to six stereo-
centers which can hardly be prepared by usual methods [1].
There are a variety of excellent examples of the synthetic use
of the intramolecular meta-cycloaddition, but the synthetic
potential of the reaction has by no means been fully
exploited [2,3]. Thus, the intramolecular meta-cycloaddition
of 5-phenylpent-1-ene derivatives has been recently used
elegantly as the key step in the synthesis towards polyqui-
nanes and fenestranes [4,5]. The former is the general
skeleton for numerous natural products and the latter of
theoretical importance with potential for use in materials and
medicinal research [6,7]. In connection with the special
character of ¯uorine atom, the introduction of ¯uorine into
this intramolecular meta-cycloaddition would be of interest.
However, to the best of our knowledge, no attempt has been
made to introduce ¯uorine into the side chain of 5-phenyl-
pent-1-ene system although several examples of ¯uorine
atom or tri¯uoromethyl group ®xed on the different position
of the phenyl ring giving the normal photo adducts have
been reported [8,9]. Herein, we present the results on the
2. Results and discussion
The vinyl bromide 1 was prepared by aldol condensation
of o-anisaldehyde and acetone followed by saturation of the
double bond with bromine and dehydrobromination with
Et3N. Two isomers 1a and 1b were obtained but not sepa-
rated by usual ¯ash chromatography. In connection with our
previous ®nding that some inexpensive tri¯uoromethylating
agents, such as FSO2CF2CO2Me, FO2SCF2CF2OCF2-
CO2Me and XCF2CO2Me (XˆCl, Br, I) can successfully
replace halogen in vinyl, allyl, aryl and alkyl halides. Here,
FSO2CF2CO2Me was found the most suitable as the tri-
¯uoromethylating agent to the halides 1a and 1b giving the
corresponding products 2a and 2b in high yields because of
its lower decomposition temperature (808C) as compared
with other tri¯uoromethylating agents [10±13]. Hydrogena-
tion of a mixture of 2a and 2b in the presence of Ranny
nickel resulted in 3a and 3b, which then reacted with vinyl
magnesium bromide to give the photo precursors 4a and 4b
(Scheme 1).
Irradiation (500 W Hg lamp, quartz vessel) of 4a and 4b
as a 0.2% (W/V) solution in hexane caused the rapid
disappearance of the bichromophores and the clean forma-
tion of intramolecular meta adducts, angular triquinane 5a
and 5b (Scheme 2) in 2.0 h. At this step, 5a and 5b can be
successfully separated by ¯ash chromatography.
*Corresponding author. Tel.: +86-21-641-63300; fax: +86-21-641-
66128; e-mail: chenqy@pub.sioc.ac.cn
0022-1139/99/$ ± see front matter # 1999 Elsevier Science S.A. All rights reserved.
PII: S 0 0 2 2 - 1 1 3 9 ( 9 9 ) 0 0 0 4 2 - 1

150
X.-C. Guo, Q.-Y. Chen / Journal of Fluorine Chemistry 97 (1999) 149±156
Scheme 1. a. 5% NaOH, H2O; b. Br2CCl4, hn; c. Et3N, CH2Cl2; d. FSO2CF2CO2 Me, Cul, DMF, 808C; e. Ranny Ni, 50 atm, MeOH; f. CH2 ˆ CHBr, Mg,
THF.
The structures of the photo adducts were established by
1D- and 2D-NMR measurements. The triquinane skeleton
of 5a and 5b was determined by H, H COSY and 13C,
1H COSY. NOESY data con®rmed the relative stereochem-
istry of the products. In 5a, crosspeaks were observed due to
H(10)±Me(9) and H(8)±Me(9) interactions establishing that
H(8), Me(9) and H(10) were positioned cis with each other.
Similarly, in compound 5b, crosspeaks were also observed
for H(2)±H(11) and H(8)±Me(9), showing that the positions
of H(8), Me(9) and H(11) were cis with each other.
1
1
Interestingly, the cis relationship between CF3 and OH
groups was also found in both 5a and 5b. The cis relation-
ship of 5a can be ascribed to the preparation of photo
precursor 4. 4 was prepared by the Grignard reaction of
vinyl bromide with ketone 3 (Scheme 1). In our opinion, the
nucleophilic attack may follow the Felkin±Anh Model [14],
that is, the Grignard reagent attacks the carbonyl group
opposite to more steric hindered benzyl group to give the
conformer 6, in which the relative stereochemistry of CF3
Scheme 2.

X.-C. Guo, Q.-Y. Chen / Journal of Fluorine Chemistry 97 (1999) 149±156
151
There is no big difference in the intramolecular meta-
photocycloaddition reaction between alcohols and their
tri¯uoroacetates except that the ratio of 9:10 rises from
1:2 to 1:1 when tri¯uoroacetates were employed instead of
alcohols (Fig. 1).
The structures of compounds 9 and 10 were determined
by NMR. An X-ray crystal diffraction of 9b was also
obtained, which gave the most direct support of the structure
of the stereochemistry, especially of the relative positions of
MeO and OCOCF3 groups.
It is known that this photochemical methodology can also
be applied to gain access to the potentially useful azatri-
quinanes [18,19]. How will tri¯uoroacetylated 3-benzyl-
aminopropene act in the photocycloaddition? It was found
that photo precursor 11 underwent highly selective intra-
molecular meta-photocycloaddition yielding only the linear
azatriquinane 12 (Scheme 6).
Scheme 3.
and OH is ®xed due to the hydrogen bonding between OH
and MeO groups. The cis relationship between CF3 and OH
is, thus, retained during the photo reaction (Scheme 3).
The relationship between OH and MeO was also only cis
due to an intramolecular hydrogen bonding between the two
groups when the addition reaction took place as shown in 6,
which is similar to that in the non-¯uorinated systems re-
ported by Zhang et al. [15,16] and Crimmins and Choy [17].
The formation of angular product 5 can be described as
bonding between C(2) and C(4) (Scheme 4). The regio-
selectivity controlled by the donating MeO group at the
benzene ring is understandable because this group strongly
stabilizes the partial positive charge of the zwitterion 7.
When 5-(o-methoxyphenyl)pent-1-en-3-ols or their tri-
¯uoroacetates, 8 , were irridiated under the same conditions
as above, both angular adduct 9 and linear adduct 10 were
obtained (Scheme 5).
For bichromophores 11a and 11b, the shorter bond
lengths and smaller angles of the ±CH2±N±CH2± tether,
compared to hydrocarbon analogues, result in asymmetry of
the S1 arene [18,19]. In transition state of photo-precursor
11, the intramolecular cycloaddition of the ethene to the S1
benzene ring may not be a synchronous process. Thus C-10
becomes tetrahedral before C-30 and so cyclopropane ring
formation between C-20 and C-60 is favored giving the linear
isomer with high selectivity.
Scheme 4.

152
X.-C. Guo, Q.-Y. Chen / Journal of Fluorine Chemistry 97 (1999) 149±156
Scheme 5.
signi®cant role for this cycloaddition in the synthesis of
polyquinanes and their ¯uorinated analogues.
3. Experimental
IR spectra were taken on Schimadzu-440 and Perkin-
1
Elmer 983 spectrometers. H NMR spectra were recorded
on Varian EM-360A (60 MHz), FX-90Q (90 MHz) and
Bruker AM 300 (300 MHz) NMR spectrometers.
19F NMR spectra were recorded on a Varian EM-360L
(56.4 MHz) NMR spectrometer. Chemical shifts were
reported in parts per million relative to TMS as an internal
standard for 1H NMR and to CF3COOH as an external
standard for 19F NMR. The solvent for NMR measurement
was CDCl3. MS and HRMS spectra were recorded on
HP5989A and Finnigan MAT mass spectrometers. X-ray
structure was recorded on Rigaku AFC7R diffractometer.
A 500 W medium pressure Hg lamp was used as the light
source.
Fig. 1. X-ray crystal structure of 9b.
For non-substituted 11c, only fragmentation instead of
intramolecular cycloaddition reaction occurred and gave no
photo adducts. It shows that a donating substituent is
essential to this reaction due to the introduction of tri¯uor-
oacetyl group into this system.
In conclusion, we have achieved the meta-photocycload-
dition of side-chain tri¯uoromethylated or tri¯uoroacety-
lated arene to ole®n and their aza-analogues. The facility
and effectiveness of this methodology clearly suggest a
3.1. Trifluoromethylation of the vinyl bromide 1
A mixture of vinyl bromide (1, 1.30 g, 5.1 mmol), CuI
(970 mg, 5.1 mmol) and FSO2CF2CO2Me (4.86 g,
25.5 mmol) in dried DMF (10 ml) was stirred at 808C under
nitrogen for 15 h. Then, Cu was ®ltered off and the solution
was poured into water. The mixture was extracted with ether
(3Â25 ml). The combined organic layer was washed with
water (3Â10 ml) and dried over anhydrous Na2SO4. After
removal of the solvent under vacuum, the crude material
was puri®ed with ¯ash chromatography (petroleum
ether:etherˆ10:1) to give 2 (1.20 g) as light yellowish
oil. Yield: 96%.
IR (Film), ꢀ: 2470 (w), 1705 (vs), 1641 (m), 1600 (m),
1485 (s), 1465 (s), 1438 (m), 1294 (vs), 1281 (vs), 1179 (vs),
1
1
1159 (vs), 1026 (m), 756 (s) cm . H NMR (90 MHz,
CDCl3) ꢁ: 2.20 (s, 3H, E), 2.50 (s, 3H, Z), 3.90 (s, 3H), 6.90±
7.60 (stack, 5H, 2b), 6.90±7.60 (stack, 4H, 2b), 8.07 (s, 1H,
2a) ppm. 19F NMR (56.4 MHz, CDCl3) ꢁ: 20.7 (s, 2b),
Scheme 6.

X.-C. Guo, Q.-Y. Chen / Journal of Fluorine Chemistry 97 (1999) 149±156
153
‡
‡
15.0 (s, 2a) ppm. EIMS (m/z): 245 (M ‡1, 20), 244 (M ,
¯ash chromatography (petroleum ether:ether ˆ10:1ꢀ5:1) to
give 5a and 5b as light yellowish oil.
‡
‡
7.8), 229 (M ±Me, 16), 213 (M ±OMe, 100), 195 (5.7), 151
(8.9), 133 (7.6), 109 (5.2), 89 (3.9), 77 (2.3). HRMS Calc.
for C12H11O2F3 (M ): 244.0711; Found: 244.0695.
5a. Yield: 250 mg (32%). IR (Film), ꢀ: 3490 (br), 2941
(m), 2834 (w), 1592 (m), 1497 (s), 1246 (vs), 1141 (m),
‡
1
1
1105 (s), 1026 (m), 754 (m) cm . H NMR (300 MHz,
CDCl3, 1H, 1H COSY, 13C, 1H COSY and NOESY), ꢁ: 1.25
(s, 3H, Me), 1.53 (dd, 1H, Jˆ13.2, 7.4 Hz, H-7), 2.00±2.10
(stack, 2H, H-11,H-11), 2.08±2.15 (stack, 2H, H-6, H-8),
2.19 (m, 1H, H-4), 2.44 (dd, 1H, Jˆ14.5, 9.8 Hz, H-7), 2.65
(m, 1H, H-10), 3.36 (s, 3H, OMe), 5.54 (d, 1H, Jˆ1.0 Hz, H-
2), 5.58 (m, 1H, H-3) ppm. 13C NMR (75 MHz, CDCl3) ꢁ:
22.44 (t), 23.64 (q, Me), 24.60 (t), 35.56 (d), 40.43 (d), 53.76
(q, C-10, Jˆ24 Hz), 57.07 (q, OMe), 65.64 (s), 68.86 (d),
80.22 (s), 90.07 (s), 125.59 (d), 128.07 (q, CF3, Jˆ280 Hz),
137.00 (d) ppm. 19F NMR (56.4 MHz, CCl4 ), ꢁ: 12.7 (d,
3.2. Preparation of 3
A mixture of 2a and 2b (2.28 g, 9.34 mmol, 2a:2bˆ3:2)
in MeOH (15 ml) was hydrogenated under freshly made
Ranny Ni at 50 atm for 6 h, then, the catalyst was ®ltered off
and the solvent was removed under vacuum. The crude
material was puri®ed with ¯ash chromatography (petroleum
ether:etherˆ15:1) to give 3 (1.20 g 3a:3bˆ3:2) as colorless
oil. Yield: 100%.
IR (Film), ꢀ: 2950 (m), 1730 (s), 1600 (m), 1500 (s), 1470
(s), 1440 (m), 1360 (s), 1250 (vs), 1160 (s), 1105 (vs), 1050
(m), 1030 (m), 760 (s) cm . 1H NMR (90 MHz, CDCl3) ꢁ:
‡
‡
Jˆ8.0 Hz) ppm. EIMS (m/z): 274 (M , 18), 257 (M -OH,
1
‡
‡
16), 256 (M ±H2O, 11), 236 (M -2F, 44), 216 (27), 201
(7.7), 187 (8.4), 151 (7.5), 121 (100), 109 (9.3), 91 (50), 77
2.10 (s, 3H), 2.25 (m, 1H), 3.08 (d, 1H), 3.52 (d, 1H), 3.85 (s,
3H), 6.80±7.20 (stack, 4H) ppm. 19F NMR (56.4 MHz,
‡
(11), 71 (57). HRMS: Calc. for C14H17O2F3 (M ):
274.1181; Found: 274.1195.
‡
CCl4) ꢁ: 10.7 (d, Jˆ8 Hz) ppm. EIMS (m/z): 246 (M ,
100), 213 (4.4), 203 (18), 183 (6.0), 177 (5.8), 151 (7.1), 121
(88), 108 (16), 91 (59), 77 (13), 43 (79).
5b. Yield: 180 mg (23%). R (Film), ꢀ: 3477 (br), 2940
(m), 1800 (w), 1497 (s), 1466 (m), 1373 (m), 1315 (m), 1246
(vs), 1142 (s), 1107 (s), 1053 (m), 1032 (m), 932 (m), 754 (s)
1
3.3. Preparation of 4
cm . 1H NMR (300 MHz, CDCl3, 1H, 1H COSY and 13C,
1H COSY) ꢁ: 1.38 (s, 3H, Me), 1.63 (m, 2H, H-7, H-7), 2.03
(d, 1H, Jˆ1.9 Hz, H-10), 2.06 (s, 1H, H-10), 2.21±2.25
(stack, 2H, H-4, H-6), 2.49 (dd, 1H, Jˆ12.0, 6.8 Hz, H-8),
3.15 (m, 1H, H-11), 3.33 (s, 3H, OMe), 5.72 (dd, 1H, Jˆ6.0,
2.2 Hz, H-2), 5.75 (m, 1H, H-3) ppm. 13C NMR ꢁ: 16.38 (t),
23.94 (q, Me), 27.91 (t), 35.08 (d), 35.24 (d), 57.10 (q,
OMe), 60.67 (q, C11, Jˆ25 Hz), 65.88 (s), 73.89 (s), 75.24
(d), 88.14 (s), 125.94 (d), 129.07 (q, CF3, Jˆ276 Hz),
133.78 (d) ppm. 19F NMR d: 11.0 (d, Jˆ8.0 Hz) ppm.
A mixture of 3a and 3b (550 mg, 2.2 mmol) in dried THF
(5.0 ml) was added dropwise to Grignard reagent prepared
from Mg (840 mg,35 mmol) and vinyl bromide (3.2 g,
30 mmol) in THF (45 ml). sat. NH4Cl (50 ml) was added
after stirring for 3 h and stirred for another 10 min. The
mixture was extracted with ether (3Â20 ml). The combined
organic layer was washed with brine (3Â10 ml) and dried
over anhydrous Na2SO4. After removal of the solvent under
vacuum, the crude material was puri®ed with ¯ash chro-
matography (petroleum ether:etherˆ5:1) to give 4 (630 mg,
4a:4bˆ3:2) as light yellowish oil. Yield: 87%.
‡
EIMS (m/z): 275 (M ‡1, 6.0), 245 (5.5), 233 (6.4), 222
(6.6), 207 (6.1), 195 (7.4), 177 (5.6), 149 (11), 128 (8.0), 119
(17), 95 (15), 91 (22), 77 (17), 57 (29), 44 (100). HRMS
‡
IR (Film), ꢀ: 3481 (br), 2952 (m), 2845 (w), 1800 (m),
1497 (s), 1467 (m), 1371 (w), 1246 (s), 1142 (m), 1096 (s),
Calc. for C14H17O2F3 (M ): 274.1181; Found: 274.1201.
1-(o-Methoxyphenyl)pentan-3-one and 5-(o-methoxy-
phenyl)-2,2-dimethyl-pentan-3-one were prepared by aldol
condensation of o-anisaldehyde and 3,3-dimethylbutan-2-
one or butan-2-one followed by catalytic hydrogenation
according to standard procedures. These two ketones were
used to prepare the respective 8a and 8c as follows:
1
1
1028 (m), 930 (m) cm . H NMR (300 MHz, CDCl3) ꢁ:
1.29 (s, 3H, Me, 4b), 1.43 (s, 3H, Me, 4a), 1.50 (s, 1H, OH),
2.62±2.82 (stack, 2H), 3.12 (m, 1H), 3.78 (s, 3H, OMe, 4a),
3.81 (s, 3H, OMe, 4b), 5.16 (ddd, 1H, Jˆ26.7, 10.5, 1.0 Hz),
5.39 (ddd, 1H, Jˆ24.0, 17.1, 1.1 Hz), 6.04 (m, 1H), 6.83±
6.94 (stack, 2H), 7.15±7.25 (stack, 2H) ppm. 19F NMR
(56.4 MHz, CDCl3) ꢁ: 14.5 (d, Jˆ8 Hz, 4b), 15.7 (d,
3.5. Preparation of 8a and 8c
‡
‡
Jˆ8 Hz, 4a) ppm. EIMS (m/z): 274 (M , 6.9), 256 (M ±
H2O, 4.1), 236 (21), 216 (17), 201 (5.4), 185 (4.6), 173 (3.5),
149 (3.5), 121 (50), 108 (12), 91 (57), 77 (15), 71 (100).
Ketone (4.5 mmol) in dried THF (5.0 ml) was added
dropwise to Grignard reagent prepared from Mg (25 mmol)
and vinyl bromide (22.5 mmol) in THF (20 ml). sat. NH4Cl
(20 ml) was added after stirring for 1 h and stirred for
another 10 min. The mixture was extracted with ether
(3Â20 ml). The combined organic layer was washed with
brine (3Â10 ml) and dried over anhydrous Na2SO4. After
removal of the solvent under vacuum, the crude material
was puri®ed with ¯ash chromatography (petroleum
ether:etherˆ15:1) to give 8 (980 mg) as colorless oil.
‡
HRMS Calc. for C14H17O2F3 (M ): 274.1181; Found:
274.1149.
3.4. Irradiation of 4
A solution of 4a and 4b (780 mg, 2.8 mmol) in 450 ml
hexane was irradiated in a quartz vessel for 2.0 h. After
removal of the solvent, the crude material was separated by

154
X.-C. Guo, Q.-Y. Chen / Journal of Fluorine Chemistry 97 (1999) 149±156
8a. Yield: 87%. IR (Film), ꢀ: 3544 (br), 2959 (s), 1599
(m), 1495 (s), 1465 (m), 1242 (s), 1051 (m), 1034 (m),
3.7. Irradiation of 8
1
1
920 (m), 754 (s) cm . H NMR (300 MHz, CDCl3) ꢁ:
0.93 (s, 9H, 3Me), 1.67 (br, 1H, OH), 1.82±1.87 (stack,
2H), 2.49±2.57 (stack, 2H), 3.83 (s, 3H, OMe), 5.28
(td, 2H, Jˆ15, 1.6 Hz), 5.96 (dd, 1H, Jˆ17, 11 Hz),
6.83±6.91 (stack, 2H), 7.12±7.18 (stack, 2H) ppm. EIMS
A solution of 8 (4.0 mmol) in hexane (450 ml) was
irradiated in a quartz vessel for 2.0 h. After removal of
the solvent, the crude material was separated by ¯ash
chromatography (petroleum ether:etherˆ15:1ꢀ10:1) to
give 9 and 10.
9a. Yield: 23%, yellow oil. IR (Film), ꢀ: 3569 (m), 3493
(w), 3037 (w), 2962 (vs), 2955 (vs), 2941 (s), 1591 (w),
1439 (m), 1392 (m), 1215 (m), 1116 (m), 766 (m) cm
1H NMR (300 MHz, CDCl3) ꢁ: 0.80 (s, 9H, 3Me), 1.39±
1.50 (stack, 2H), 1.72 (m, 1H), 1.95±2.17 (stack, 6H), 3.38
(s, 3H, OMe), 5.40±5.44 (stack, 2H) ppm. 13C NMR
(75 MHz, CDCl3) ꢁ: 25.28 (t), 25.69 (t), 25.88 (q, 3C),
35.82 (d), 37.59 (s), 39.45 (t), 40.32 (d), 57.05 (q, OMe),
63.08 (d), 68.58 (s), 86.45 (s), 89.97 (s), 124.73 (d), 138.18
‡
‡
‡
(m/z): 248 (M , 0.25), 231 (M ±OH, 2.0), 203 (M ±
‡
3Me, 0.67), 191 (M ±t-Bu, 46), 173 (2.2), 161 (2.0),
1
135 (4.7), 121 (100), 105 (2.7), 91 (31), 77 (5.2). Analysis
Calc. for C16H24O2, C, 77.37; H, 9.74; Found: C, 77.30; H,
10.02.
.
8c. Yield: 87%. IR (Film), ꢀ: 3470 (br,m), 2935 (s), 2835
(s), 1600 (m), 1587 (m), 1495 (s), 1465 (m), 1245 (vs),
1
1054 (m) cm
.
1H NMR (300 MHz, CDCl3) ꢁ: 0.92
(t, 3H, Jˆ7.5 Hz,Me), 1.58±1.66 (stack, 2H), 1.78±1.85
(stack, 3H), 2.63±2.69 (dd, 2H, Jˆ7.2,3.4 Hz), 3.84
(s, 3H, OMe), 5.18 (dd,1H, Jˆ17.4, 1.2 Hz), 5.88 (dd,
1H, Jˆ17.4, 10.9 Hz), 6.84±6.93 (stack, 2H), 7.14±7.22
‡
‡
(d) ppm. EIMS (m/z): 248 (M , 2.9), 231 (M ±OH, 73), 217
‡
‡
‡
(M ±OMe, 46), 199 (51), 191 (M ±t-Bu, 42), 173 (M ±
H2O±t-Bu, 100), 159 (31), 143 (17), 131 (53), 121 (88), 105
(19), 91 (47). Analysis Calc. for C16H24O2 C, 77.37; H, 9.74
Found: C, 77.19; H, 10.13.
‡
‡
(stack, 2H) ppm. EIMS (m/z): 220 (M , 2.1), 202 (M ±
‡
‡
H2O, 2.6), 191 (M ±Et, 11), 173 (M ±H2O±Et, 26), 136
(30), 121 (100), 107 (20), 91 (44), 77 (11). Analysis
Calc. for C14H20O2: C 76.31, H 9.15; Found: C 75.81,
H 9.40.
10a. Yield: 47%, white crystal. IR (KBr) ꢀ: 3460 (m),
2961 (s), 2907 (m), 2808 (m), 1584 (w), 1570 (m), 1556 (m),
1
1
1116 (m), 1072 (m), 741 (m) cm . H NMR (300 MHz,
CDCl3) ꢁ: 0.90 (s, 9H, 3Me), 1.39 (m, 1H), 1.48 (m, 1H),
1.76 (m, 1H), 1.98 (brs, 1H), 2.12±2.33 (stack, 4H), 3.34
(dd, 1H, Jˆ5.2, 2.5 Hz), 3.40 (s, 3H, OMe), 5.52 (m, 1H),
5.60 (dd, 1H, Jˆ5.5, 2.2 Hz) ppm. 13C NMR (75 MHz,
CDCl3) ꢁ: 24.09 (t), 26.17 (q, 3C, t-Bu), 36.85 (s), 37.89 (t,
2C), 41.74 (d), 47.66 (d), 51.58 (s), 54.21 (d), 56.48 (q,
OMe), 84.94 (s), 89.01 (s), 127.21 (d), 132.89 (d). EIMS
3.6. Preparation of 8b and 8d
To 8a or 8c (1.0 mmol) was added (CF3CO)2O
(4.0 mmol), pyridine (3.0 mmol) and catalytic DMAP in
dried CH2Cl2 (10 ml) at 08C and stirred for 12 h, then, ether
was added. The mixture was washed with sat. NaHCO3, 2N
HCl, CuSO4 solution and brine, dried over anhydrous
Na2SO4. After removal of the solvent under vacuum, the
crude material was puri®ed with ¯ash chromatography
(petroleum ether:etherˆ15:1) to give 8b or 8d as light
yellowish oil.
‡
‡
‡
(m/z): 248 (M , 1.0), 231 (M ±OH, 14), 215 (M ±H2O±t-
‡
‡
Bu, 21), 199 (16), 191 (M ±Bu, 37), 173 (M ±Bu±H2O,
63), 159 (33), 147 (17), 131 (60), 121 (100), 105 (23), 91
(62). Analysis: Calc. for C16H24O2 C, 77.37; H, 9.74;
Found: C, 77.73; H, 10.26.
8b: Yield: 89%. IR (Film), ꢀ: 2970 (m), 2953 (m), 1782
(s), 1610 (w), 1495 (m), 1244 (s), 1221 (s), 1169 (s), 752 (m)
9b. Yield: 30%, white crystal. IR (Film), ꢀ: 2974 (m),
2941 (m), 1776 (s), 1713 (w), 1601 (w), 1477 (w), 1460 (w),
1448 (w), 1373 (m), 1366 (m), 1215 (s), 1165 (s), 1155 (s),
1
1
cm . H NMR (300 MHz, CDCl3) ꢁ: 1.14 (s, 9H, 3Me),
2.35±2.41 (stack, 2H), 2.60±2.66 (stack, 2H), 3.87 (s, 3H,
OMe), 5.00 (d, 2H, Jˆ7.1 Hz), 5.48 (t, 1H, Jˆ7.1 Hz),
6.86±6.90 (stack, 2H), 7.12±7.26 (stack, 2H) ppm.
19F NMR (56.4 MHz, CDCl3) ꢁ: 3.0 ppm. EIMS (m/z):
1
1
1001 (w), 760 (w) cm . H NMR (300 MHz, CDCl3) ꢁ:
0.91 (s, 9H, 3Me), 1.61±1.70 (stack, 3H), 2.06±2.28 (stack,
3H), 2.36±2.43 (stack, 2H), 3.25 (s, 3H, OMe),3.30 (m, 1H),
5.53±5.58 (stack, 2H) ppm. 13C NMR (75 MHz, CDCl3) ꢁ:
25.30 (t), 25.55 (t), 26.64 (q, 3C), 33.79 (t), 35.05 (d), 39.40
(s), 40.66 (d), 56.70 (q, OMe), 64.50 (d), 67.64 (s), 90.01 (s),
105.20 (s), 114.76 (q, CF3, Jˆ286 Hz), 125.80 (d), 137.42
(d), 156.78 (t, CO, Jˆ41 Hz) ppm. 19F NMR (56.4 MHz,
‡
‡
344 (M , 3.5), 241 (M ±OCOCF3, 0.77), 231 (0.76), 211
(0.88), 173 (3.2), 159 (1.2), 135 (1.8), 121 (100), 91 (34), 77
(3.7). HRMS Calc. for C18H23O3F3: 344.1599; Found:
344.1591.
‡
‡
8d: Yield: 93%. IR (Film), ꢀ: 3030 (m), 2971 (m), 1772
1
CCl4): 1.9 ppm. EIMS (m/z): 344 (M , 2.4), 287 (M ±t-
‡
(vs), 1440 (m), 1221 (m), 1165 (s) cm
.
1H NMR
Bu, 3.3), 249 (5.2), 231 (M ±OCOCF3, 40), 215 (30), 199
‡
(90 MHz, CCl4) ꢁ: 1.05 (t, 3H, Me), 1.80±2.87 (stack,
6H), 3.97 (s, 3H, OMe), 5.42 (m, 1H), 5.58 (m, 1H),
6.17 (m, 1H), 6.82±7.27 (stack, 4H) ppm. 19F NMR
(16), 183 (9.1), 173 (M ±OCOCF3±t-Bu, 100), 159 (17),
143 (20), 135 (32), 121 (32), 91 (35). Analysis Calc.
for C18H23O3F3: C, 62.78; H, 6.73; Found: C, 62.91; H,
6.97.
X-Ray Details: C18H23O3F3; colorless, prismatic;
Crystal System, orthorhombic; Lattice Type, Primitive;
Lattice Parameter, aˆ13.264 A, bˆ15.203A, cˆ8.630A,
‡
(56.4 MHz, CDCl3) ꢁ: 2.5 ppm. EIMS (m/z): 316 (M ,
‡
‡
1.0), 220 (M ±COCF3, 9.8), 203 (M ±OCOCF3, 6.8), 192
‡
(27), 173 (M ±OCOCF3±Et, 100), 158 (15), 135 (14), 121
(92), 91 (47).

X.-C. Guo, Q.-Y. Chen / Journal of Fluorine Chemistry 97 (1999) 149±156
155
Vˆ1740 A3, Space Group, P212121 (#19); Z valueˆ4;
No. Observations, I>3.00s (I); Residuals, Rˆ0.056,
Rwˆ0.059.
10d. Yield: 21%, yellow oil. IR (Film), ꢀ: 3040 (w), 2971
(m), 2939 (m), 1771 (vs), 1440 (m), 1378 (s), 1221 (vs),
1
1
1163 (vs), 1126 (m), 975 (w) cm . H NMR (300 MHz,
CDCl3) ꢁ: 0.86 (t, 3H, Jˆ7.5 Hz), 1.67±1.75 (stack, 3H),
2.11±2.26 (stack, 6H), 2.80±2.90 (stack, 2H), 3.26 (s, 3H,
OMe), 5.53 (dd, 1H, Jˆ5.6, 1.2 Hz), 5.59 (dd, 1H, Jˆ5.5,
2.4 Hz) ppm. 13C NMR (75 MHz, CDCl3) ꢁ: 7.70 (q, Me),
23.63 (t), 28.79 (t), 37.15 (t), 39.31 (d), 40.15 (t), 50.20 (d),
50.46 (s), 51.42 (d), 56.81 (q, OMe), 90.34 (s), 95.91 (s),
114.66 (q, CF3, Jˆ285 Hz), 128.30 (d), 132.21 (d), 156.12
(q, CO, Jˆ12 Hz) ppm. 19F NMR (56.4 MHz, CDCl3) ꢁ:
10b. Yield: 28%, yellow oil. IR (Film), ꢀ: 2940 (m), 2934
(m), 1780 (s), 1364 (w), 1219 (m), 1169 (s), 1155 (s), 1128
1
(m), 745 (s) cm . 1H NMR (300 MHz, CDCl3) ꢁ: 0.97 (s,
9H, t-Bu), 1.58 (m, 1H), 1.67 (m, 1H), 1.95 (m, 1H), 2.13
(brs, 1H), 2.30±2.39 (stack, 4H), 3.28 (m, 1H), 3.39 (s, 3H,
OMe), 5.54 (m, 1H), 5.67 (m, 1H) ppm. 19F NMR
(56.4 MHz, CDCl3) ꢁ: 4.0(s) ppm. EIMS (m/z): 344
‡
‡
‡
(M , 2.6), 287 (M ±t-Bu, 1.0), 247 (M ±COCF3, 1.0),
‡
‡
‡
‡
231 (M ±1-OCOCF3, 30), 230 (M ±1-OCOCF3, 30), 215
‡
2.3 ppm. EIMS (m/z): 316 (M , 1.7), 302 (M ±CH2,
‡
(40), 199 (42), 183 (9.3), 174 (M ±OCOCF3±t-Bu, 25), 173
‡
0.16), 285 (1.3), 251 (1.2), 219 (M ±OCOCF3, 2.0), 203
(12), 187 (16), 173 (100), 159 (19), 131 (19), 121 (35), 91
(38), 79 (13).
(M ±1-OCOCF3±t-Bu, 100), 158 (22), 143 (24), 121 (29).
‡
HRMS Calc. for C18H23O3F3 (M ): 344.1599; Found:
344.1608.
The elemental analyses of 9d and 10d could not be
determined due to their slow decomposition at room tem-
perature.
9c. Yield: 28%, yellow oil. IR (Film), ꢀ: 3442 (m, br),
2937 (s), 1745 (m), 1462 (m), 1393 (m), 1215 (m), 1178 (m),
1
1019 (m) cm . 1H NMR (300 MHz, CDCl3) ꢁ: 0.87 (t, 3H,
Me, Jˆ7.5 Hz), 1.24 (m, 1H), 1.42±1.56 (stack, 2H), 1.67±
2.20 (stack, 8H), 2.45 (br, 1H), 3.30 (s, 3H, OMe), 5.48±5.52
(stack, 2H) ppm. 13C NMR (75 MHz, CDCl3) ꢁ: 8.76 (q,
Me), 22.94 (t), 23.42 (t), 30.90 (t), 35.53 (d), 40.14 (t), 40.42
(d), 56.89 (q, OMe), 67.11 (d), 77.53 (s), 83.32 (s), 90.18 (s),
3.8. Preparation of compound 11
3-(o-Methoxybenzyl)aminoprop-1-ene (or 3-benzylami-
noprop-1-ene) was prepared by condensation of o-anisal-
dehyde (or benzaldehyde) and allylic amine followed by
reduction with NaBH4 in MeOH according to standard
procedures.
3-(o-Methylbenzyl)aminoprop-1-ene was prepared by
condensation of o-methylbenzyl chloride and allylic amine
followed by reduction with LiAlH4 in dried THF according
to standard procedures. The amines obtained were tri-
¯uoroacetylated to 11 as follows:
‡
124.30 (d), 138.40 (d) ppm. EIMS (m/z): 220 (M , 5.3), 203
‡
‡
‡
‡
(M ±OH, 15), 202 (M ±H2O, 8.7), 191 (M ±Et, 22), 173
(M ±H2O±Et, 84), 159 (7.7), 135 (25), 121 (100), 105 (13),
‡
91 (54), 85 (29). HRMS Calc. for C14H20O2 (M ):
220.1463; Found: 220.1437.
10c. Yield: 48%, white crystal. IR (Film), ꢀ: 3458 (br, s),
3050 (w), 2934 (vs), 1661 (w), 1586 (w), 1451 (s), 1398 (s),
1
1
1298 (s), 1130 (s) cm . H NMR (300 MHz, CDCl3) ꢁ:
0.90 (t, 3H, Jˆ4.2 Hz), 1.43±1.57 (stack, 4H), 1.80±2.02
(stack, 4H), 2.14 (m, 1H), 3.32 (m,1H), 3.37 (s, 3H, OMe),
5.50 (m,1H), 5.59 (m,1H) ppm. 13C NMR (100 MHz,
CDCl3) ꢁ: 8.36 (q, Me), 23.67 (t), 33.34 (t), 37.36 (t),
40.26 (d), 41.10 (t), 51.07 (d), 51.50 (s), 52.87 (d), 56.41
(q, OMe), 80.05 (s), 89.31 (s), 127.43 (d), 132.38 (d). EIMS
To the amine (8.1 mmol) was added (CF3CO)2O
(24 mmol), pyridine (8.1 mmol) and catalytic amount of
DMAP in dried ether (10 ml) at 08C and stirred or re¯uxed
for 8±16 h, the mixture was poured into ice-water and
extracted with ether(60 mlÂ3), washed with water until
pH 7, then dried over anhydrous Na2SO4. After removal
of the solvent under vacuum, the crude material was puri®ed
with ¯ash chromatography (petroleum ether: etherˆ15:1) to
give 11 as colorless oil.
‡
‡
‡
(m/z): 220 (M , 2.3), 202 (M ±H2O, 20), 191 (M ±Et,
‡
100), 173 (M ±Et±H2O, 31), 171 (33), 170 (75), 169 (18),
160 (13), 159 (36), 155 (65), 141 (43), 129 (23), 115 (32),
11a. Yield: 92%. IR (Film), ꢀ: 2942 (w), 2840 (w), 1691
(s), 1603 (w), 1591 (w), 1495 (m), 1460 (m), 1442 (m), 1291
‡
105 (9.8), 91 (20), 77 (10). HRMS Calc. for C14H20O2 (M ):
220.1463; Found: 220.1451.
1
(w), 1207 (m), 1146 (s), 1115 (m), 757 (m) cm 1H NMR
9d. Yield: 19%, yellow oil. IR (Film), ꢀ: 2939 (m), 1772
1
(s), 1449 (m), 1378 (m), 1165 (s) cm
(300 MHz, CDCl3) ꢁ: 3.83 (s, 3H, OMe), 3.97±4.14 (stack,
2H), 4.66 (s, 2H), 5.09±5.30 (stack, 2H), 5.77 (m, 1H), 6.88±
7.09 (stack, 2H), 7.20±7.34 (stack, 2H) ppm. 19F NMR
.
1H NMR
(300 MHz, CDCl3) ꢁ: 0.85 (t, 3H, Me), 1.62±1.77 (stack,
3H), 2.08±2.26 (stack, 6H), 2.76±2.87 (stack, 2H), 3.25 (s,
3H, OMe), 5.54 (m, 1H), 5.58 (m, 1H) ppm. 13C NMR
(75 MHz, CDCl3) ꢁ: 8.44 (q), 15.29 (d), 24.51 (t), 25.45 (t),
29.49 (t), 34.81 (d), 38.78 (t), 40.32 (d), 56.40 (q), 66.80 (d),
77.52 (s), 90.06 (s), 98.38 (s), 125.83 (d), 137.17 (d), 116.56
(q, CF3), 156.48 (q, CO). 19F NMR (56.4 MHz, CDCl3) ꢁ:
‡
(56.4 MHz, CDCl3) ꢁ: 9.3 ppm. EIMS (m/z): 273 (M -
2, 10), 232 (100), 226 (0.82), 209 (1.3), 191 (0.63), 176
(1.6), 149 (4.8), 137 (5.1), 121 (31), 107 (62), 91 (52).
Analysis: Calc. for C13H14O2NF3: C, 57.14; H, 5.16; N 5.13;
Found: C, 56.79; H, 5.55; N, 5.04.
11b : Yield: 98%. IR (Film), ꢀ: 2931 (w), 1693 (vs), 1450
(m), 1290 (s), 1207 (s), 1145 (s), 992 (m), 937 (w), 747 (w)
‡
‡
2.1 (s) ppm. EIMS (m/z): 316 (M , 1.5), 301 (M ±Me,
‡
1
1
0.5), 216 (M ±Me±COCF3‡1,24), 203 (11), 191 (21), 173
cm . H NMR (300 MHz, CDCl3) ꢁ: 2.27 (s, 3H, Me),
3.94 (dd, 2H, Jˆ20, 5.9 Hz), 4.68 (s, 2H), 5.09±5.33 (stack,
2H), 5.76 (m, 1H), 7.06±7.26 (stack, 4H) ppm. 19F NMR
(90), 154 (100), 131 (26), 121 (62), 105 (33), 91 (67), 77
(34).

156
X.-C. Guo, Q.-Y. Chen / Journal of Fluorine Chemistry 97 (1999) 149±156
‡
(56.4 MHz, CDCl3) ꢁ: 9.3 ppm. EIMS (m/z): 258 (M ‡1,
49.34 (s), 52.47 (t), 57.50 (d), 62.50 (s), 116.42 (q, CF3,
Jˆ286 Hz), 127.76 (d), 133.36 (d), 155.25 (q, CO,
Jˆ37 Hz) ppm. 19F NMR (60 MHz, CDCl3) ꢁ:
‡
‡
‡
21), 257 (M , 22), 256 (M -1, 100), 216 (M -1-allyl, 10),
205 (3.0), 191 (3.3), 174 (4.8), 161 (2.0), 149 (4.2), 136 (16),
115 (3.8), 105 (15), 91 (4.9). Analysis Calc. for
C13H14ONF3: C, 60.69; H, 5.48; N 5.45; Found: C,
60.41; H, 5.40; N, 5.21.
11c. Yield: 78%. IR (Film), ꢀ: 3067 (w), 3031 (w), 2933
(w), 1669 (vs), 1604 (w), 1456 (m), 1295 (w), 1207 (s), 1145
(s), 1004 (w) cm . H NMR (90 MHz, CCl4) ꢁ: 3.85 (d,
2H), 4.60 (s, 2H), 5.05±5.40 (stack, 2H), 5.75 (m, 1H), 7.05±
7.45 (stack, 5H) ppm. 19F NMR (60 MHz, CDCl3) ꢁ:
‡
‡
5.7 ppm. EIMS (m/z): 257(M , 3.6), 242 (M ±Me,
3.4), 216 (56), 203 (0.75), 188 (3.2), 176 (8.5), 129 (6.9),
115 (8.9), 107 (22), 91 (100), 77 (11). Analysis: Calc. for
C13H14ONF3: C, 60.69; H, 5.48; N, 5.45; Found: C, 60.48;
H, 5.43; N, 5.22.
1
1
Acknowledgements
‡
‡
9.5 ppm. EIMS (m/z): 243 (M , 6.5), 217 (M ±C2H2,
‡
‡
1.6), 202 (M -allyl, 100), 174 (M ±CF3, 0.74), 152 (3.5),
132 (7.1), 107 (18), 91 (67), 79 (19).
We would like to thank Prof. Cong Zhang for his helpful
discussion and the Chinese National Natural Science Foun-
dation for the ®nancial support.
3.9. Irradiation of 11
A solution of 11 (5.9 mmol) in hexane (450 ml) was
irradiated in a quartz vessel for 2.0 h. After removal of
the solvent, the crude material was separated by ¯ash
chromatography (petroleum ether:ether ˆꢀ10:1) to give
12 as light yellowish oil.
References
[1] P.A. Wender, T.W. von Geldern, B.H. Levine, J. Am. Chem. Soc. 110
(1988) 4858.
[2] J. Cornelisse, Chem. Rev. 93 (1993) 615.
[3] D. De Keukeleire, S.-L. He, Chem. Rev. 93 (1993) 359.
[4] P.A. Wender, S.K. Singh, Tetrahedron Lett. 31 (1990) 2517.
[5] D. De Keukeleire, S.-L. He, J. Chem. Soc., Chem. Commun. (1992)
419.
12a. Yield: 32.5%. IR (Film), ꢀ: 2938 (m), 1691 (vs),
1589 (w), 1516 (w), 1458 (m), 1350 (w), 1256 (m), 1207 (s),
1
1172 (s), 1145 (s), 760 (w) cm
.
1H NMR (300 MHz,
[6] J. Mani, S. Schuettel, C. Zhang, P. Bigler, Ch. Mueller, R. Keese,
Helv. Chim. Acta 72 (1989) 487.
CDCl3) ꢁ: 1.86±2.07 (stack, 3H), 2.22 (m, 1H), 2.38 (m,
1H), 3.37 (s, 3H, OMe), 3.43±3.99 (stack, 6H), 5.60 (m,
1H), 5.66 (m, 1H) ppm. 19F NMR (56.4 MHz, CDCl3) ꢁ:
6.0 ppm. 13C NMR (75 MHz, CDCl3) ꢁ: 38.07 (d), 45.24
(t), 45.92 (t), 52.83 (d), 52.94 (t), 52.99 (d), 56.98 (q), 77.30
(s), 89.58 (s), 116.31 (q, CF3, Jˆ286 Hz). 127.35 (d), 133.28
(d), 154.60±156.06 (q, CO, Jˆ36 Hz) ppm. EIMS (m/z): 273
[7] C. Zhang, D. Bourgin, R. Keese, Tetrahedron 47 (1991) 3059.
[8] H.A. Neijenesch, E.J. Ridderikhoff, C.A. Ramsteijn, J. Cornelisse, J.
Photochem. Photobiol., A; Chem. 48 (1989) 317.
[9] H.A. Neijenesch, R.J.P.J. De Ruiter, E.J. Ridderikhoff, J.O. van den
Ende, L.J. Laarhoven, L.J. van Putten, J. Cornelisse, J. Photochem.
Photobiol., A; Chem. 60 (1991) 325.
[10] Q.-Y. Chen, S.-W. Wu, J. Chem. Soc., Chem. Commun. (1989) 705.
[11] Q.-Y. Chen, J.-X. Duan, J. Chem. Soc., Chem. Commun. (1993)
1390.
‡
(M , 3.0), 232 (31), 204 (1.9), 176 (3.1), 161 (5.4), 148
(3.3), 121 (15), 107 (21), 91 (40), 77 (20), 69 (100).
Analysis: Calc. for C13H14O2NF3: C, 57.14; H, 5.16; N,
5.13; Found: C, 56.75; H,5.67; N, 5.05.
[12] D.-B. Su, J.-X. Duan, Q.-Y. Chen, Tetrahedron Lett. 32 (1991)
7689.
[13] J.-X. Duan, D.-B. Su, Q.-Y. Chen, J. Fluorine Chem. 61 (1993) 279.
[14] Y.-D. Wu, K.N. Houk, J. Am. Chem. Soc. 109 (1987) 908.
[15] C. Zhang, X.-C. Guo, Synth. Commun. 24 (1994) 3157.
[16] C. Zhang, X.-C. Guo, X.-M. Shen, Y.-F. Xu, Synth. Commun. 25
(1995) 775.
12b. Yield: 38%. IR (Film), ꢀ: 3034 (w), 2928 (m), 2867
(m), 1796 (w), 1683 (vs), 1457 (m), 1256 (m), 1206 (s),
1
1
1142 (s), 756 (m) cm . H NMR (300 MHz, CDCl3) ꢁ:
1.31 (s, 3H, Me), 1.70±1.79 (stack, 2H), 1.93 (m, 1H), 2.53
(m, 1H), 2.98 (dd, 1H, Jˆ5.1, 2.2 Hz), 3.43±3.94 (stack,
4H), 5.46 (m, 1H), 5.63 (m, 1H) ppm. 13C NMR (75 MHz,
CDCl3) ꢁ: 13.43 (q), 38.59 (d), 41.44 (d), 46.25 (t), 47.04 (t),
[17] M.T. Crimmins, A.L. Choy, J. Am. Chem. Soc. 119 (1997) 10237.
[18] D.C. Blackmore, A. Gilbert, Tetrahedron Lett. 35 (1994) 5267.
[19] D.C. Blackmore, A. Gilbert, Tetrahedron Lett. 36 (1995) 2307.