Experimental
Cation 3:
To a solution of 4,6,8-trimethylazulene 2 (10 mmol, 1.7 g) in ether (30 ml), HBF4
(3 ml of 54% solution in ether) was added dropwise under nitrogen. A white precipitate
formed. After 10 min., ferrocene carboxaldehyde 1 (20 mmol, 4.2 g) was added and
the mixture stirred for 14 h. A dark green precipitate appeared which was filtered off,
washed carefully with ether, and dried in vacuum. Yield 4.5 g of green powder (quantitative).
C24H23BF4Fe, calc. C, 63.5; H, 5.1; found C, 63.1; H, 4.8%.
M.p. > 320 oC, 1H-NMR (d6-acetone): 2.92 (s, 3H); 3.06 (s, 3H); 3.48 (s, 3H); 4.55
(s, 5H); 5.42 (s, 2H); 5.56 (s, 2H); 7.73 (d, 4.9 Hz, 1H); 8.30 (d, 4.9 Hz, 1H);
8.44 (s, 2H); 9.23 (s, 1H). 13C-NMR (d6-acetone): 26.2, 28.0, ca. 30 (under solvent): CH3;
74.0 (ferrocene, unsubst.); 75.5, 81.1 (ferrocene, subst. ring, CH); 83.5 (ferrocene, quart. C);
129.2, 140.4, 143.7, 144.1, 158.2 (azulene, quart. C); 135.3, 145.6, 153.6, 153.9, 155.8,
157.1 (azulene, CH).
Amine 4:
To a solution of cation 3 (2.0 mmol, 910 mg) in dichloromethane (10 ml)
was added (S)-(-)-phenylethylamine (5.0 mmol, 0.64 ml). The colour changed to
dark violet. After 30 min., water (10 ml) was added, and the organic layer was
dried with sodium sulfate. The crude material contained two diastereoisomeric
amines in the ratio 6:1. Recrystallization from dichloromethane / hexane yielded
the major isomer, yield 480 mg (49 %), m.p. 138 - 140 oC.
C32H33FeN, calc. C, 78.9; H, 6.8; N, 2.9; found C, 79.1; H, 6.9; N, 3.0%.
The minor diastereoisomer could not be obtained in pure form, but was identified
by NMR spectroscopy.
Major diastereoisomer:
1H-NMR (CDCl3): 1.32 (d, 6.0 Hz, 3H); 2.39 (s, 3H); 2.53 (s, 3H);
2.86 (s, 3H); 3.60 (m, 1H); 3.82 (s, br, 1H); 3.95 (s, br, 1H); 4.04 (s, br, 1H);
4.14 (s, br, 1H); 4.06 (s, 5H); 5.20 (s, 1H); 6.77 (s, 1H); 6.94 (s, 1H);
7.44 (d, 5.0 Hz, 1H); 7.93 (d, 5.0 Hz, 1H); 7.20 - 7.35 (m, 5H).
13C-NMR (CDCl3): 25.3, 25.7, 28.1, 28.4 (CH3); 52.5, 55.1
(CH); 66.5, 67.5, 67.9 (ferrocene, subst. ring, CH); 68.1 (ferrocene, unsub.);
96.6 (ferrocene, quart.); 115.7, 126.5, 128.8, 133.4 (azulene, CH); 126.7,
126.9, 128.3 (phenyl, CH); 132.4, 134.2, 137.5, 144.6, 145.1, 146.0, 146.4
(quart. C).
Minor diastereoisomer:
1.32 (d, 6.1 Hz, 3H); 2.52 (s, 3H); 2.82 (s, 3H); 2.86 (s, 3H); 3.86 (m, 1H);
3.57 (s, br, 1H); 3.98 (s, br, 1H); 4.30 (s, br, 2H); 4.06 (s, 5H); 5.51 (s, 1H); 6.87 (s, 1H); 7.05 (s, 1H); 7.39 (d, 5.2 Hz, 1H);
7.92 (d, 5.2 Hz, 1H); 7.20 - 7.31 (m, 5H).
Alcohols 6:
To a solution of 4,6,8-trimethylazulene (2.0 mmol, 340 mg) in dry THF (20 ml)
at -70 oC under nitrogen, a solution of LDA (2 mmol, 3 ml) in THF was added.
Upon warming to -10 oC, an orange colour evolved. The ferrocene derivative
5 (2.0 mmol) was added at this temperature, and the colour turned to violet.
After warming to room temperature, 20 ml of water were added, and the aqueous
layer was extracted with 4 times 20 ml of ether. The combined organic phases
were dried, and the solvent was evaporated. Chromatography (silicagel, dichloromethane)
yielded the products as a 9:1 mixture of regioisomers 6 and 7 which
could not be separated, but were identified by NMR.
6a (R = H, from ferrocene carboxaldehyde):
Yield 32%, 1H-NMR (CDCl3): 2.83 (s, 6H); 3.02 (d, 6.6 Hz, 1H);
3.44 (m, 1H); 4.60 (dt, 6.6 Hz, 1.5Hz, 1H); 4.80 (m, 1H);
3.98 (m, 1H); 4.08 (m, 1H); 4.20 (m, 1H); 4.30 (m, 1H); 4.15 (s, 5H);
6.95 (s, 2H); 7.33 (d, 4.0 Hz, 2H); 7.66 (t, 4.0 Hz, 1H).
13C-NMR (CDCl3): 25.0 (CH3); 51.5 (CH2);
64.9 (CH); 67.3, 67.5, 67.9, 71.5 (ferrocene, subst. ring, CH);
68.2 (ferrocene, unsub.); 92.8 (ferrocene, quart.); 115.9, 127.4, 132.8 (azulene,
CH); 136.3, 145.3, 145.9 (azulene, quart.).
6b (R = methyl, from acetylferrocene): Yield 25%, 1H-NMR (CDCl3):
1.52 (s, 3H); 2.80 (s, 6H); 3.06 (d, 12.8 Hz, 1H); 3.10 (d, 12.8 Hz, 1H);
3.90 (m, 1H); 4.10 (m, 1H); 4.17 (m, 2H);
4.21 (s, 5H); 6.80 (s, 2H); 7.33 (d, 5.5 Hz, 2H);
7.68 (t, 5.5 Hz, 1H).
6c (R = phenyl, from benzoylferrocene): Yield 32%, 1H-NMR
(CDCl3):
2.64 (s, 6H); 3.35 (d, 15.5 Hz, 1H); 3.49 (d, 15.5 Hz, 1H); 4.02 (m, 2H); 4.11
(s, 5H); 4.15 (m, 1H); 4.20 (m, 1H); 6.63 (s, 2H); 7.17 (m, br, 5H);
7.22 (d, 5.6 Hz, 2H); 7.60 (t, 1H). 13C-NMR (CDCl3):
25.1 (CH3); 56.0 (CH2); 67.0 (CH) ; 68.5 (ferrocene, unsub.);
67.5, 67.8, 75.5, 76.0 (ferrocene, CH);
99.8 (ferrocene, quart.); 115.6, 125.9, 127.5 (azulene, CH);
126.4, 127.4, 129.6 (phenyl, CH); 133.1, 138.8, 144.2, 146.1 (quart. C).
Alkenes 8a and 9a
To a solution of a mixture of the alcohols 6a and 7a
(0.3 mmol, 120 mg) in dichloromethane (20 ml) was added triethylamine
(0.2 ml). Methanesulfonyl chloride (0.6 mmol, 0.5 ml) was added at -70 deg.
and the mixture stirred at room temperature for 16 h. After aqueous workup,
the organic solution was purified by chromatography (basic alumina, ether)
to give a mixture of the alkenes (yield 85%, ratio 5:1). The major isomer could be
be obtained in pure form by chromatography (silicagel, hexane), m.p. 58 - 60 oC.
C24H22Fe, calc. C, 78.7; H, 6.1; found C, 78.9; H, 6.0%.
Major isomer 8a: 1H-NMR (CDCl3): 2.92 (s, 3H); 6.83 (d, 16.4 Hz,
1H); 7.09 (d, 16.4 Hz, 1H); 4.16 (s, 5H); 4.35 (m, 2H); 4.51 (m, 2H); 7.26
(s, 2H); 7.32 (d, 5.0 Hz, 2H); 7.65 (m, 1H). 13C-NMR (CDCl3):
25.4 (CH3); 69.4 (ferrocene, unsub.); 67.4, 69.7 (ferrocene, subst. ring,
CH); 82.8 (ferrocene, quart.); 130.0, 131.4 (alkene); 116.4, 123.8, 132.8 (azulene,
CH); 136.3, 143.9, 145.2 (azulene, quart.).
Minor isomer 9a: 1H-NMR (CDCl3): 2.68 (s, 3H); 2.86 (s, 3H);
4.17 (s, 5H); 4.35 (m, 2H); 4.54 (m, 2H); 7.16 (d, 16.0 Hz, 1H); 7.64 (d, 16.0 Hz, 1H);
7.03 (s, 1H); 7.41 (s, 1H); 7.37 (m, 1H); 7.55 (m, 1H); 7.68 (m, 1H). 13C-NMR
(CDCl3): 25.2, 29.0 (CH3); 69.7 (ferrocene, unsub.);
67.5, 69.7 (ferrocene, CH); 82.7 (ferrocene, quart.); 127.4, 133.5 (alkene);
115.2, 116.7, 121.7, 126.8, 132.2 (azulene, CH); 134.9, 136.5, 143.7, 145.6
(azulene, quart.).