A R T I C L E S
Vicario et al.
3
3
1H, CH), 6.74 (d, JHH ) 8.1 Hz, 1H), 6.80 (t, JHH ) 7.7 Hz, 1H),
7.23 (t, 3JHH ) 7.7 Hz, 1H), 7.34 (t, 3JHH ) 8.1 Hz, 1H), 7.41 (d, 3JHH
from heptane. 1H NMR (400 MHz, CDCl3): δ 0.87 (s, 9H, CH3), 3.00
2
3
2
(d, JHH ) 15.0 Hz, 1H, CH2), 3.37 (dd, JHH ) 5.5 Hz, JHH ) 15.0
3
3
) 5.9 Hz, 1H), 7.42 (d, JHH ) 5.5 Hz, 1H), 7.47 (d, JHH ) 8.1 Hz,
1H), 7.55 (d, 3JHH ) 8.4 Hz, 1H), 7.77 (d, 3JHH ) 7.7 Hz, 1H), 7.79 (d,
3JHH ) 7.7 Hz, 1H), 7.87 (dd, 3JHH ) 3.3, 3JHH ) 5.8 Hz, 1H), 7.89 (d,
3JHH ) 8.1 Hz, 1H), 7.94 (d, 3JHH ) 8.4 Hz, 1H), 8.03 (dd, 3JHH ) 3.3,
3JHH ) 5.5 Hz, 1H). 13C NMR (75 MHz, CDCl3): δ 18.5 (CH3), 20.9
(CH3), 31.2 (CH), 36.2 (CH2), 56.3 (CH), 118.8 (CH), 119.6 (CH),
123.2 (CH), 124.2 (CH), 125.2 (CH), 125.8 (CH), 125.9 (CH), 126.6
(CH), 126.7 (CH), 126.8 (CH), 126.9 (CH), 127.3 (CH), 128.6 (CH),
129.1 (C), 130.7 (CH), 131.0 (C), 132.4 (C), 137.1 (C), 137.9 (C),
139.3 (C), 139.7 (C), 140.3 (C), 148.2 (C), 150.4 (C). m/z (EI, %) )
372 (M+, 46), 329 (100). HRMS (EI): calcd for C29H24, 372.186; found,
372.188.
Hz, 1H, CH2), 3.97 (s, 3H, OCH3), 4.39 (d, 3JHH ) 5.5, 1H, CH), 6.62-
4
3
6.66 (m, 2H), 6.96 (dd, JHH ) 2.2 Hz, JHH ) 8.4 Hz, 1H), 7.15 (m,
3
3
3
1H), 7.34 (dd, JHH ) 7.3 Hz, JHH ) 7.7 Hz, 1H), 7.46 (dd, JHH
)
7.7 Hz, 3JHH ) 7.7 Hz, 1H), 7.53 (d, 3JHH ) 7.7 Hz, 1H), 7.63 (d, 3JHH
3
3
) 7.7 Hz, 1H), 7.72 (d, JHH ) 8.4 Hz, 1H), 7.75 (d, JHH ) 8.1 Hz,
1H), 7.87-7.90 (m, 2H), 7.93 (d, JHH ) 7.7 Hz, 1H). 13C NMR (75
3
MHz, CDCl3): δ 28.8 (CH3), 35.8 (C), 37.4 (CH2), 55.7 (OCH3), 59.7
(CH), 111.5 (CH), 112.6 (CH), 117.9 (CH), 120.0 (CH), 123.0 (CH),
124.8 (CH), 125.2 (CH), 125.9 (CH), 126.6 (CH), 127.0 (CH), 127.1
(CH), 128.7 (CH), 129.1 (C), 130.4 (CH), 132.1 (C), 134.2 (C), 137.1
(C), 139.1 (C), 139.4 (C), 141.1 (C), 147.5 (C), 149.8 (C), 149.9 (C),
158.7 (C). m/z (EI, %) ) 416 (M+, 25), 359 (100). HRMS (EI): calcd
for C31H28O, 416.214; found, 416.215.
UV Monitoring of the Rotary Cycle. A UV-vis spectrum of a
solution of 9a (2.31 × 10-6 M) or 9b (a 2.15 × 10-6 M) at -20 °C or
9c (1.78 × 10-6 M) at -60 °C in hexane was taken before and after
irradiation, showing a shift in the absorption in the region 390-400
nm to 425-440 nm and indicating formation of the less stable isomer.
Warming of the samples resulted in the same UV-vis spectra as before
irradiation, indicating thermal isomerization. λmax (ꢀ): 9ast, 392 (20.500);
9aunst, 415 (17.900); 9bst, 390 (21.300); 9bunst, 430 (18.100); 9cst, 398
(20.800); 9cunst, 442 (18.300) nm (see Figure 3 for representative spectra
of 9a and Supporting Information for spectra of 9b and 9c).
CD Monitoring of the Rotary Cycle. A molar CD spectrum of an
enantiopure solution of 9a (7.32 × 10-6 M) or 9b (a 8.01 × 10-6 M)
at -20 °C or 9c (9.04 × 10-6 M) at -60 °C in hexane was taken
before and after 10 min irradiation, showing in all cases complete
inversion of the CD spectra and indicating the formation of the unstable
isomer by cis/trans isomerization. Warming of the samples to room
temperature showed again inversion of the CD signal to the original
spectra, indicating formation of the stable isomer by thermal isomer-
9-(2-tert-Butyl-2,3-dihydro-cyclopenta[a]naphthalen-1-ylidene)-
9H-fluorene (9c). The general procedure B was followed, using 2-tert-
butyl-2,3-dihydro-cyclopenta[a]naphthalen-1-thione 15b (0.254 g, 1
mmol) and 9-diazo-9H-fluorene 17 (0.384 g, 2 mmol), affording 0.251
g (65%) of the alkene 9c as a yellow solid. 1H NMR (400 MHz,
CDCl3): δ 0.87 (s, 9H, CH3), 3.02 (d, 2JHH ) 15.0 Hz, 1H, CH2), 3.41
3
2
3
(dd, JHH ) 5.5 Hz, JHH ) 15.0 Hz, 1H, CH2), 4.56 (d, JHH ) 5.5,
3
1H, CH), 6.70-6.76 (m, 2H), 7.21 (t, JHH ) 7.3 Hz, 1H), 7.34 (t,
3JHH ) 8.1 Hz, 1H), 7.39-7.42 (m, 2H), 7.46 (t, JHH ) 8.1 Hz, 1H),
3
7.54 (t, 3JHH ) 8.4 Hz, 1H), 7.75-7.77 (m, 2H), 7.86 (dd, 3JHH ) 3.7,
3JHH ) 7.0 Hz, 1H), 7.89 (d, JHH ) 8.1 Hz, 1H), 7.94 (d, JHH ) 8.1
Hz, 1H), 8.35 (dd, 3JHH ) 3.7, 3JHH ) 7.0 Hz, 1H). 13C NMR (75 MHz,
CDCl3): δ 28.7 (CH3), 35.9 (C), 37.3 (CH2), 59.5 (CH), 118.6 (CH),
119.5 (CH), 123.0 (CH), 125.1 (CH), 125.2 (CH), 125.8 (CH), 126.0
(CH), 126.2 (CH), 126.6 (CH), 126.8 (CH), 126.9 (CH), 127.0 (CH),
128.7 (CH), 129.1 (C), 130.4 (CH), 131.1 (C), 132.1 (C), 137.3 (C),
139.1 (C), 139.3 (C), 139.6 (C), 140.7 (C), 147.6 (C), 149.8 (C). m/z
(EI, %) ) 386 (M+, 31), 329 (100). HRMS (EI): calcd for C30H26,
386.203; found, 386.203.
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3
ization. λmax (∆ꢀ): 9ast, 235 (-133.3), 276 (+73.0), 286 (+50.1); 9aunst
,
9-(2-Methyl-2,3-dihydro-cyclopenta[a]naphthalen-1-ylidene)-9H-
fluorene (4). The general procedure A was reported with 39% yield.21
Procedure B was followed, using 2-methyl-2,3-dihydro-cyclopenta[a]-
naphthalene-1-thione 15c (0.212 g, 1 mmol) and 9-diazafluorene 17
(0.384 g, 2 mmol), affording 0.441 g (65%) of alkene 4 as a yellow
solid. Spetroscopic data are in agreement with literature values.
trans-9-(2-tert-Butyl-2,3-dihydro-cyclopenta[a]naphthalen-1-yl-
idene)-2-methoxy-9H-fluorene (trans-20). The general procedure B
was followed, using 2-tert-butyl-2,3-dihydro-cyclopenta[a]naphthalen-
1-thione 15b (0.254 g, 1 mmol) and 2-methoxy-9-diazafluorene 19
(0.444 g, 2 mmol), affording 0.262 (63%) of a mixture cis/trans-20
(1:2 ratio) as a yellow solid. Separation of the isomers was carried out
by column chromatography (SiO2/AgNO3 9:1, pentane/Et2O 95:5), and
61 mg of pure trans-20 was obtained after two consecutive crystal-
237 (+80.6), 275 (-47.8); 9bst, 235 (-118.6), 270 (+88.0); 9bunst
,
238 (+76.4), 280 (-65.3); 9cst, 235 (-118), 269 (+103.8), 287 (+94.4);
9cunst, 242 (-85.2), 261 (-65.1), 286 (-59.2) nm (see Figure 4 for
representative spectra of 9a and Supporting Information for spectra of
9b and 9c).
1H NMR Monitoring of the Rotary Cycle. Irradiation (366 ( 5
nm) of a solution of 9a or 9b at -40 °C, 9c at -60 °C, or cis-20 and
1
trans-20 at -85 °C in toluene-d8 was performed in a MeOH bath. H
NMR spectra of the samples before and after irradiation were taken at
the same temperature as during the irradiation experiment, showing a
completely different spectrum and indicating formation of the unstable
isomer. Upon warming of the samples to room temperature only the
1
stable isomer could be observed by H NMR.
1
2
1
9ast. H NMR (500 MHz, toluene-d8): δ 2.87 (d, JHH ) 15.2 Hz,
lizations from heptane. H NMR (400 MHz, CDCl3): δ 0.89 (s, 9H,
3
2
2
1H, CH2), 3.57 (dd, JHH ) 6.6 Hz, JHH ) 15.2 Hz, 1H, CH2), 5.20
CH3), 2.82 (s, 3H, OCH3), 3.03 (d, JHH ) 15.4 Hz, 1H, CH2), 3.41
3
3
3
3
2
3
(d, JHH ) 6.6 Hz, 1H, CH), 6.66 (dd, JHH ) 7.2 Hz, JHH ) 7.8 Hz,
(dd, JHH ) 5.5 Hz, JHH ) 15.4 Hz, 1H, CH2), 4.45 (d, JHH ) 5.5,
1H), 6.83 (d, 3JHH ) 6,9 Hz, 1H), 6.88 (dd, 3JHH ) 7.5 Hz, 3JHH ) 7.8
4
4
3
1H, CH), 6.29 (d, JHH ) 2.2 Hz, 1H), 6.77 (dd, JHH ) 2.2 Hz, JHH
3
) 8.4 Hz, 1H), 7.27-7.47 (m, 4H), 7.55 (d, 3JHH ) 8.1 Hz, 1H), 7.60
Hz, 1H), 6.95-7.15 (m, 9H overlapped with toluene), 7.19 (dd, JHH
) 6.9 Hz, 3JHH ) 7.8 Hz, 1H), 7.47 (d, 3JHH ) 8.1 Hz, 1H), 7.56-7.60
3
3
3
(d, JHH ) 8.4 Hz, 1H), 7.73 (d, JHH ) 7.3 Hz, 1H), 7.80 (d, JHH
)
3
3
8.1 Hz, 1H), 7.87 (d, 3JHH ) 8.1 Hz, 1H), 7.92 (d, 3JHH ) 8.1 Hz, 1H),
(m, 3H), 7.65 (d, JHH ) 7.8 Hz, 1H), 8.01 (d, JHH ) 8.4 Hz, 1H).
9aunst. 1H NMR (500 MHz, toluene-d8): δ 3.09-3.21 (m, 2H, CH2),
4.39 (dd, 3JHH ) 7.3 Hz, 3JHH ) 7.7 Hz, 1H, CH), 6.72 (dd, 3JHH ) 7.3
Hz, 3JHH ) 7.6 Hz, 1H), 6.76 (dd, 3JHH ) 6.0 Hz, 3JHH ) 7.3 Hz, 1H),
8.27 (d, JHH ) 7.7 Hz, 1H). 13C NMR (75 MHz, CDCl3): δ 28.7
3
(CH3), 35.9 (C), 37.3 (CH2), 54.6 (OCH3), 59.5 (CH), 109.9 (CH), 115.4
(CH), 118.8 (CH), 119.4 (CH), 123.1 (CH), 125.0 (CH), 125.1 (CH),
125.2 (CH), 126.8 (CH), 127.0 (CH), 127.3 (CH), 128.7 (CH), 129.0
(C), 130.4 (CH), 131.4 (C), 132.1 (C), 132.5 (C), 138.6 (C), 139.0
(C), 139.3 (C), 140.8 (C), 147.6 (C), 149.7 (C), 158.2 (C). m/z (EI, %)
) 416 (M+, 25), 359 (100). HRMS (EI): calcd for C31H28O, 416.214;
found, 416.215.
3
6.95-7.15 (m, 10H overlapped with toluene), 7.18 (dd, JHH ) 7.3
Hz, 3JHH ) 7.6 Hz, 1H), 7.29 (d, 3JHH ) 6.0 Hz, 1H), 7.42 (d, 3JHH
)
7.6 Hz, 1H), 7.19 (d, 3JHH ) 7.6 Hz, 1H), 7.61 (d, 3JHH ) 6.0 Hz, 1H),
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3
7.62 (d, JHH ) 8.3 Hz, 1H), 8.04 (d, JHH ) 8.3 Hz, 1H).
1
3
9bst. H NMR (500 MHz, toluene-d8): δ 0.38 (d, JHH ) 6.6 Hz,
3
cis-9-(2-tert-Butyl-2,3-dihydro-cyclopenta[a]naphthalen-1-ylidene)-
2-methoxy-9H-fluorene (cis-20). Following separation of the isomers
by column chromatography (SiO2/AgNO3 9:1, pentane/Et2O 95:5), 29
mg of pure cis-20 was obtained after three consecutive crystallizations
3H, CH3), 0.95 (d, JHH ) 6.6 Hz, 3H, CH3), 2.21 (m, 1H, CH), 2.58
2
3
2
(d, JHH ) 15.3 Hz, 1H, CH2), 3.02 (dd, JHH ) 5.6 Hz, JHH ) 15.3
Hz, 1H, CH2), 4.08 (dd, 3JHH ) 4.2 Hz, 3JHH ) 5.6 Hz, 1H, CH), 6.66
(dd, 3JHH ) 7.0 Hz, 3JHH ) 8.4 Hz, 1H), 6.93-7.16 (m, 3H overlapped
9
5134 J. AM. CHEM. SOC. VOL. 128, NO. 15, 2006