R. Goumont, K. Magder, M. Tordeux, J. Marrot, F. Terrier, C. Wakselman
FULL PAPER
Cycloadduct 6c was obtained as an oil in quantitative
Comparison of the cyclopentadiene adducts 6a؊d and
1
yield upon treatment of 4c with cyclopentadiene. The H- 9a؊d showed that the triflone derivatives are clearly more
NMR spectra appeared to be similar to those of 6a and 6b, stable than the nonaflones ones. This higher stability al-
and contained signals for two new ethylenic protons Ha lowed us to study the structure of 6a in great detail by
(δ ϭ 5.74) and Hb (δ ϭ 6.53) as a doublet of doublets [3J(3- NMR and X-ray analysis. Both methods showed that Diel-
HϪHa) ϭ 9.8 Hz and 3J(HaϪHb) ϭ 15.2 Hz] and a doublet sϪAlder cycloaddition resulted in endo isomers of 6a؊d.
[3J(HaϪHb) ϭ 15.2 Hz], respectively.
The NMR data of compounds 6a؊d and 9a؊d are also
Treatment of 4d with cyclopentadiene 5 led, after purifi- very similar. It can therefore be concluded that the stereo-
cation, to a 50% yield of adduct 6d. Detailed NMR analysis chemistry of the nonaflones derivatives 9a؊d is also endo,
in CDCl3 solution (Table 3), including NOE experiments, whereas they were previously considered to be exo cycload-
identified the stereochemistry as endo. Saturation of 3-H ducts.[15] Addition of (E)-4a؊d or (E)-8a؊d to cyclopen-
resulted in a positive NOE with the bridge proton 7-H (δ ϭ tadiene involves secondary orbital interactions with the aro-
2.33) and saturation of 2Ј-H gave rise to two positive re- matic ring and the ester group. That no trace of the exo
sponses, with 3-H (δ ϭ 4.30) and 4-H (δ ϭ 3.52).
diastereoisomer could be detected in the present study may
be due to the larger steric constraints of the nonafluorobut-
anesulfonyl or trifluoromethanesulfonyl group in the exo
approach.
b. Reaction of Nonaflones 8a؊d with Cyclopentadiene
As described by Hanack,[15] vinyl nonaflones reacted
with dienes like cyclopentadiene to give cycloadducts 9a؊d
(Schemes 4 and 5). These adducts[15] were obtained in good
yields, but they appeared to be somewhat less stable than
Conclusion
We have shown that vinyl triflones may be prepared easily
6a؊d. However, their spectral data (Table 4) agree well with and in good yields by the Knoevenagel condensation reac-
the data collected for compounds 6a؊d. NOE experiments tion. These esters may be dealkylated/decarboxylated by an-
were carried out, showing that the stereochemistry of ad- hydrous lithium iodide in dimethylformamide to produce a
ducts 8a؊d is endo. Moreover, saturation of 3-H showed in new series of vinyl triflones. Alternatively, these compounds
all cases a positive NOE with the bridge proton 7-H.
may be used in the Michael condensation reaction[1] be-
Table 4. NMR data for the adducts 9a؊d
Product
1H NMR
13C NMR
19F NMR
9a
7.10 (dd, J ϭ 7.9 Hz, J ϭ 5.3 Hz, 2 H, 2Ј-H), 164.12 (CO), 162.11 (d, J ϭ 246.9 Hz, C-4Ј), Ϫ126.1 (m, 2 F, CF2CF3),
6.95 (“t”, J ϭ 8.7 Hz, 2 H, 3Ј-H), 6.68 (dd, 138.88 (C-6), 138.65 (C-5), 134.24 (d, J ϭ 3.3 Ϫ121.3 (m, F,
2
J ϭ 5.3 Hz, J ϭ 3.2 Hz 1 H, 6-H), 6.54 (dd, Hz, C-1Ј), 130.61 (d, J ϭ 8.2 Hz, C-2Ј), 114.78 CF2CF2ϪSO2), Ϫ115.4 (s, 1
J ϭ 5.3 Hz, J ϭ 3.4 Hz, 1 H, 5-H), 4.18 (m, (d, J ϭ 21.3 Hz, C-3Ј), 89.23 (C-2), 62.67 F, C6H4ϪF), Ϫ105.3 (m, 2
1 H, 3-H), 3.87 (m, 1 H, 1-H), 3.86 (ABX3, 2 (CH2), 53.0 (C-3), 51.66 (C-1), 48.95 (C-4), F, CF2SO2), Ϫ81.1 (m, 3 F,
H, J ϭ 10.8 Hz, CH2), 3.10 (m, 1 H, 4-H), 48.20 (C-7), 12.83 (CH3)
2.48 (d, J ϭ 9.5 Hz, 1 H, 7-H), 1.65 (d, J ϭ
9.5 Hz, 1 H, 7Ј-H), 0.85 (t, J ϭ 6.9 Hz, 3
H, CH3)
CF3)
9b
9c
7.31 (m 1H, 4Ј-H), 7.26 (m, 2 H, 3Ј-H), 7.13 164.27 (CO), 138.87 (C-2Ј), 138.59 (C-4Ј), Ϫ126.1 (m, 2 F, CF2CF3),
(m, 2 H, 2Ј-H), 6.69 (m, 1 H, 6-H), 6.56 (m, 138.52 (C-1Ј), 129.01 (C-3Ј), 127.94 (C-5), Ϫ121.4
1 H, 5-H), 4.17 (m, 1 H, 3-H), 3.89 (m, 1 H, 127.38 (C-6), 89.68 (C-2), 62.55 (CH2), 53.81 CF2CF2ϪSO2), Ϫ103.3 (m,
1-H), 3.8 (ABX3, 2 H, J ϭ 11.8 Hz, CH2), (C-3), 51.70 (C-1), 49.06 (C-4), 48.24 (C-7), 2 F, CF2ϪSO2), Ϫ81.1 (m, 3
(m,
2
F,
3.13 (m, 1 H, 4-H), 2.5 (d, J ϭ 9.6 Hz, 1 H, 12.67 (CH3)
7-H), 1.65 (d, J ϭ 9.5 Hz, 1 H, 7Ј-H), 0.77 (t,
J ϭ 7.2 Hz, 3 H, CH3)
F, CF3)
7.33Ϫ7.30 (m, 5 H, 2Ј-H, 3Ј-H, 4Ј-H), 6.56 163.66 (CO), 140.57 (C-5), 137.38 (C-6), Ϫ126.2 (m, 2 F, CF2CF3),
(dd, J ϭ 5.6 Hz, J ϭ 3.3 Hz, 1 H, 5-H), 6.53 136.94 (C-1Ј), 132.24 (Cb), 129.22 (Ca), 128.55 Ϫ121.6
(m,
2
F,
(d, J ϭ 15.4 Hz, 1 H, Hb), 6.39 (d, J ϭ 5.6 (C-2Ј), 127.48 (C-4Ј), 126.27 (C-3Ј), 85.52 (C- CF2CF2ϪSO2), Ϫ108.9 (m,
Hz, 1 H, 6-H), 5.78 (dd, J ϭ 15.8 Hz, J ϭ 9.8 2), 62.7 (CH2), 52.01 (C-1), 51.58 (C-4), 49.47 2 F, CF2ϪSO2), Ϫ81.9 (m, 3
Hz, 1H, Ha), 4.20 (ABX3, J ϭ 11.2 Hz, 2 H, (C-3), 46.22 (C-7), 13.63 (CH3)
CH2), 3.96 (m, 1 H, 1-H), 3.85 (d, J ϭ 9.8 Hz,
F, CF3)
1 H, 3-H), 3.06 (m, 1 H, 4-H), 2.36 (d, J ϭ
9.8 Hz, 1 H, 7-H), 1.57 (dd, J ϭ 9.5 Hz, J ϭ 1
Hz, 1 H, 7Ј-H), 1.22 (t, J ϭ 7.2 Hz, 3 H, CH3)
9d
7.32 (dd, J ϭ 7.6 Hz, J ϭ 1 Hz, 1 H, 2Ј-H), 159.12 (CO), 148.61 (C-1Ј), 141.75 (C-5), Ϫ126.3 (m, 2 F, CF2CF3),
7.26 (t, J ϭ 7.7 Hz, 1 H, 4Ј-H), 7.19 (t, J ϭ 135.93 (C-6), 129.01 (C-2Ј), 128.03 (C-4Ј), Ϫ121.3
(m,
2
F,
7.6 Hz, 1 H, 3Ј-H), 6.97 (dd, J ϭ 8.1 Hz, J ϭ 125.42 (C-3Ј), 119.90 (C-6Ј), 117.02 (C-5Ј), CF2CF2ϪSO2), Ϫ107.1 (m,
1.5 Hz, 1 H, 5Ј-H), 6.28 (dd, J ϭ 5.6 Hz, J ϭ 75.80 (C-2), 54.93 (C-1), 51.81 (C-4), 46.12 2 F, CF2ϪSO2), Ϫ81.2 (m, 3
2.9 Hz, 1 H, 6-H), 6.23 (dd, J ϭ 5.6 Hz, J ϭ (C-7), 44.74 (C-3)
3 Hz, 1 H, 5-H), 4.30 (m, 1 H, 1-H), 4.27 (d,
J ϭ 3.6 Hz, 1 H, 3-H), 3.51 (m, 1 H, 4-H),
2.33 (d, J ϭ 9.8 Hz, 1 H, 7-H), 1.66 (dt, J ϭ
9.8 Hz, J ϭ 1.4 Hz, 1 H, 7Ј-H)
F, CF3)
2974
Eur. J. Org. Chem. 1999, 2969Ϫ2976