C. The solution of 10 (102 mg, 0.36 mmol) with 1 mol equiv.
of tert-butoxide was stirred at Ϫ70 ЊC for 40 min and then
poured into water (50 cm3). Work up gave three fractions, the
major of which, a pale yellow solid (64 mg), contained
unchanged 10 (ca. 58%), 8 and 6 in a ratio of 30:2:2. When the
reaction was repeated at Ϫ40 ЊC more uncharacterisable
material was obtained but unchanged 10 was the major com-
ponent of the product mixture.
1-[(4-Fluorophenyl)phenylmethylidene]-1H-cyclopropa[b]-
naphthalene 12
With 4-fluorobenzophenone and 18-crown-6 compound 12 was
obtained in 65% yield; mp 105–106 ЊC and identical to the
sample recorded above.
1-Fluoren-9Ј-ylidene-1H-cyclopropa[b]naphthalene 17
From fluoren-9-one the first chromatographic fraction con-
tained unchanged 10 and hydrocarbon 6 (ca. 15% each). The
second fraction contained compound 17 (70%); mp 258–259 ЊC
(lit.,20 92%, mp 259–260 ЊC).
Reactions of 1,1-bis(trimethylsilyl)-1H-cyclopropa[b]-
naphthalene 10 with potassium hydroxide
General method. A solution of 10 (96–194 mg, 0.34–68
mmol) in THF (5 cm3) was added dropwise to a stirred suspen-
sion of freshly powdered KOH (0.05–1.10 mol equiv.) in THF
(10 cm3) at the specified temperature and under an inert nitro-
gen atmosphere in a cooling/heating bath. Work up, including
warming to RT, was as for the tert-butoxide reactions described
above.
1-[4-(Dimethylamino)phenyl]methylidene-1H-cyclopropa[b]-
naphthalene 18
From 4-(dimethylamino)benzaldehyde compound 18 was
obtained in 84% yield; mp 142–144 ЊC (lit.,6 94%, mp 141–
142 ЊC).
A. Disilane 10 (100 mg, 0.35 mmol) and KOH (20 mg, 0.35
mmol) were stirred at Ϫ70 ЊC for 40 min then water (1 cm3,
55.55 mmol) was added. Work up gave 1H-cyclopropa[b]-
naphthalene 6 (41 mg, 84%) as white needles; mp, mmp 86–
87 ЊC. In like manner use of deuterium oxide (1 cm3, 55.42
mmol), 10 (194 mg, 0.68 mmol) and KOH (38 mg, 0.68 mmol)
gave white needles of [1,1-2H2]-1H-cyclopropa[b]naphthalene
[2H2]6 (95.5 mg, 70%). Two recrystallisations (light petroleum)
gave an analytical sample (12 mg, 13%); mp 85–86 ЊC (Found:
C, 92.93; H, 5.53; the H value equates to 6.95% for 3H:1D.
C11H6D2 requires C, 92.92; H, 4.25; D, 2.82; 7.07% H for
3H:1D); νmax/cmϪ1 3067, 3046, 1669, 1593, 1522, 1364, 1250,
1175, 1142, 945, 874, 847, 762, 727 and 467; δH 7.45–7.49 (BBЈ,
4/5-H), 7.60 (s, 2/7-H), 7.88–7.91 (AAЈ, 3/6-H); δC C-1 not
observed, 112.3 (C-2/7), 123.3 (C-1a/7a), 125.4 (C-4/5), 128.4
(C-3/6), 136.6 (C-2a/6a); m/z 143 (11, M ϩ 1), 142 (100, M), 141
(83, M Ϫ 1), 140 (28, M Ϫ 2H).
1-(Phenylmethylidene)-1H-cyclopropa[b]naphthalene 19
From benzaldehyde and 18-crown-6 compound 18 was obtained
in 37% yield; mp 153–155 ЊC (lit.,12 68%, mp 114–117 ЊC).
Spectroscopic data matched those reported previously.12
Acknowledgements
Generous support of this work from Victoria University
through the Internal (1996–97) and Science Faculty (1997–98)
Grants Committees is gratefully acknowledged.
References
1 For the previous part see ref. 10.
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With 10 (149 mg, 0.52 mmol), catalytic KOH (1.5 mg, 0.027
mmol) and water at Ϫ70 ЊC as above, a white solid (69 mg) that
contained unchanged disilane 10, 8 and 6 in a 3:1:130 ratio (1H
NMR) was obtained.
B. The suspension of 1 mol equiv. of KOH with 10 (98 mg,
0.35 mmol) at Ϫ70 ЊC in THF was stirred at Ϫ70 ЊC for 40 min
and then poured into water (50 cm3). Work up gave colourless
prisms of unchanged 10 (92 mg, 94%), mp, mmp 95–97 ЊC. At
temperatures of Ϫ40, Ϫ10, 0 and 17 ЊC the reactions also gave
almost quantitative recovery of unchanged 10; traces of 8 and 6
were detected by NMR from the ambient temperature reaction.
With aqueous KOH (20 mg, 0.36 mol, in 1 cm3 water) at
22 ЊC, disilane 10 (99 mg, 0.35 mmol) gave a pale yellow solid
(61 mg) that contained recovered 10, 8 and 6 in a ratio of ca.
11:3:19 representing approximately 30, 8 and 51% yields,
respectively.
C. Alkylidenecyclopropa[b]naphthalenes were provided
from disilane 10 (103 mg, 0.36 mmol) in THF (5 cm3) that
was added to a suspension of KOH (20 mg, 0.36 mmol) in
THF (10 cm3) containing the carbonyl compound (0.36
mmol) at 0 ЊC (except as specified) and the mixture stirred for
24 h while attaining RT. Reactions employing 18-crown-6
were performed using one molar equivalent (132 mg, 0.36
mmol) of the compound.
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1-(Diphenylmethylidene)-1H-cyclopropa[b]naphthalene 11
At Ϫ70 ЊC with benzophenone, chromatography afforded white
needles of cyclopropanaphthalene 6 (1.2 mg, 3%) as the most
mobile component from the crude product mixture. Further
elution (light petroleum) provided a bright yellow oil (103 mg)
which on trituration (diethyl ether) gave bright yellow needles
of compound 11 (98 mg, 90%), mp 109–111 ЊC (lit.,12 95%, mp
110–111 ЊC). Repetitions of the reaction at 0 ЊC provided 11 in
yields of 85–95%.
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Paper 8/03969K
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J. Chem. Soc., Perkin Trans. 2, 1998, 2505–2508