Cycloallenes. Part 15:1 3δ2-1H-naphthalene (2,3-didehydro-1,2- dihydronaphthalene) from 3-bromo-1,2-dihydronaphthalene

Article abstract of DOI:10.1016/S0040-4020(00)00341-0

As a test as to whether the title intermediate 13 can be liberated from 3-bromo-1,2-dihydronaphthalene (19), the latter was treated with potassium tert-butoxide (KOtBu). Being the major products, naphthalene (20) and 3-tert- butoxy-1,2-dihydronaphthalene (21) provide unambiguous evidence for the intermediacy of 13. When the reaction was carried out in the presence of furan, 2,5-dimethylfuran and spiro[2,4]hepta-4,6-diene, expected (31, 32, 33, 34) and unexpected compounds (30, 35-37) were formed, which either directly resulted from the cycloaddition of 13 or were consecutive products of cycloadducts. Performed in the presence of benzophenone, the generation of 13 gave, inter alia, naphth-2-yldiphenylmethanol (27). This product testifies the intermediacy of the naphth-2-yl anion (24), which emerged from the deprotonation of 13 and was trapped by benzophenone. (C) 2000 Elsevier Science Ltd.

Full text of DOI:10.1016/S0040-4020(00)00341-0

TETRAHEDRON
Pergamon
Tetrahedron 56 (2000) 4163±4171
Cycloallenes. Part 15:1 3d2-1H-Naphthalene
(2,3-Didehydro-1,2-dihydronaphthalene) from
3-Bromo-1,2-dihydronaphthalene
*
Stefan Groetsch, Joanna Spuziak and Manfred Christl
È
È
È
È
Institut fur Organische Chemie, Universitat Wurzburg, Am Hubland, D-97074 Wurzburg, Germany
Dedicated to Professor Rolf Huisgen on the occasion of his 80th birthday
Received 31 March 2000; accepted 18 April 2000
AbstractÐAs a test as to whether the title intermediate 13 can be liberated from 3-bromo-1,2-dihydronaphthalene (19), the latter was treated
with potassium tert-butoxide (KOtBu). Being the major products, naphthalene (20) and 3-tert-butoxy-1,2-dihydronaphthalene (21) provide
unambiguous evidence for the intermediacy of 13. When the reaction was carried out in the presence of furan, 2,5-dimethylfuran and
spiro[2,4]hepta-4,6-diene, expected (31, 32, 33, 34) and unexpected compounds (30, 35±37) were formed, which either directly resulted
from the cycloaddition of 13 or were consecutive products of cycloadducts. Performed in the presence of benzophenone, the generation of 13
gave, inter alia, naphth-2-yldiphenylmethanol (27). This product testi®es the intermediacy of the naphth-2-yl anion (24), which emerged
from the deprotonation of 13 and was trapped by benzophenone. q 2000 Elsevier Science Ltd. All rights reserved.
Introduction
evidence for the existence of 1-azacyclohexa-2,3,5-trienes
612 and 1-thiacyclohexa-2,3,5-triene (7)13 (Scheme 1).
Cyclohexa-1,2-diene (1)2 and its oxa- and azaderivatives 2,3
34±7 and 48 (Scheme 1) are extremely short-lived inter-
mediates, which in spite of that may be intercepted in addi-
tion and cycloaddition reactions very ef®ciently. The
introduction of a third double bond into the six-membered
ring, being in conjugation with the allene system, was
achieved in the case of cyclohexa-1,2,4-trienes for the ®rst
time.2 Originally, the parent 5 (Scheme 1) of these was
generated by Doering±Moore±Skattebùl reactions and
intercepted by activated ole®ns.5,9 Later, 5 was made acces-
sible by two further routes.10,11 Shevlin et al. provided
The ®rst benzo-annulated derivative of 5 (compound 9 in
Scheme 2) was liberated from the bromonaphthalene 8 by
Scheme 1.
Keywords: allenes; cycloadditions; eliminations; rearrangements.
* Corresponding author. Tel.: 149-931-8885344; fax: 149-931-8884606;
e-mail: christl@chemie.uni-wuerzburg.de
Scheme 2.
0040±4020/00/$ - see front matter q 2000 Elsevier Science Ltd. All rights reserved.
PII: S0040-4020(00)00341-0

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S. Groetsch et al. / Tetrahedron 56 (2000) 4163±4171
2H-chromene (15) to give the oxaderivative 16 of 1316
served as models. Apart from the interception of 16 by
furan with formation of the [412] cycloadduct 18b, which
rearranges to 18a on heating at 1108C, that by KOtBu/
HOtBu is particularly remarkable (Scheme 4), since the
resulting acetal 17 testi®es a highly polar character of 16.16
Results and Discussion
Treatment of 3-bromo-1,2-dihydronaphthalene (19) with
KOtBu in the absence and presence of benzophenone
Scheme 3.
As a precursor for 13, we chose 19, which is accessible from
1-tetralone in three steps with an overall yield of 50%.17 The
treatment of 19, dissolved in anhydrous tetrahydrofuran
(THF), with 2.3 equiv. of KOtBu gave a 73:22:3:2 mixture
of naphthalene (20), 3-tert-butoxy-1,2-dihydronaphthalene
(21), 2,20-binaphthyl (22) and 1,2-dihydronaphthalene (23)
in a yield of 92% (Scheme 5). When less than 2 equiv. of
KOtBu were employed, 19 was not consumed completely.
Five equivalents of KOtBu changed the product ratio to
84:12:2:2. The identi®cation of the known compounds 20,
22 and 23 was trivial, whereas 21 revealed its structure by
the characteristic NMR signals of the enol ether subunit.
potassium tert-butoxide (KOtBu) in a b-elimination
reaction and trapped by KOtBu as well as 1,3-diphenyl-
isobenzofuran (DPIBF) furnishing the enol ether 10 and
the cycloadducts 11, respectively.14
The parent compound to 9, i.e. the title cycloallene 13, was
shown to emerge from the dihalocarbene adducts 12 of
indene in Doering±Moore±Skattebùl reactions (Scheme
3).5,9 If the experiments are conducted in the presence of
activated ole®ns, [212] cycloadducts of 13 result with
styrene (see 14),5,9 a-methylstyrene, 2,3-dimethylbuta-1,3-
diene9 and buta-1,3-diene9,15 and [412] cycloadducts with
2,3-dimethylbuta-1,3-diene9, buta-1,3-diene9,15 and cyclo-
penta-1,3-diene.15
The outcome of this reaction is best rationalised by assum-
ing the b-elimination of HBr from 19 with formation of the
desired intermediate 13. There is no evidence for the alter-
native b-elimination, which would generate the isomeric
cyclic alkyne. Since the yield of the products is close to
quantitative, KOtBu must interact with 13 ef®ciently in
two ways. The nucleophilic attack at the central allene
carbon atom and the protonation of the resulting allyl
anion by HOtBu leads to the enol ether 21 (Scheme 6).
This pathway is analogous to that to 1014 or to 1-tert-butoxy-
cyclohex-1-ene, the ®nal product of the interception of 1 by
tBuO22, but different to that to 17, formed eventually after
the addition of tBuO2 to 16.16 The enol ether 21 on one side
and the allyl ether (acetal) 17 on the other underline the
different electronic character of 13 and 16. While 16 is
best described as a pyrylium ylide, the ground state of 13
Although methyllithium serves as reagent, the deprotona-
tion of 13, which would give rise to the naphth-2-yl anion
(24), does not interfere. This is astounding, since the
aromatic character of 24 causes an enormous driving force
for this conversion. In the present work, we have revisited
this problem and examined the possibility to generate 13 by
a b-elimination as in the case of 9. In addition to the reaction
of 8 with KOtBu,14 the analogous transformations of
1-bromocyclohexa-1,4-diene to give 511 and of 3-bromo-
Scheme 4.
Scheme 5.

S. Groetsch et al. / Tetrahedron 56 (2000) 4163±4171
4165
could be demonstrated beyond doubt as well (Scheme 7).
This was achieved by the synthesis of authentic samples of
2718 and 28 by reaction of benzophenone with naphth-2-yl
magnesium bromide and 1,2-dihydronaphth-2-yl potas-
sium,19 respectively. Hence, 27 and 28 prove that the
carbanions 24 and 26 emerge from 19 and are intercepted
by benzophenone.
Treatment of 3-bromo-1,2-dihydronaphthalene (19)
with KOtBu in the presence of furan, 2,5-dimethylfuran
and spiro[2,4]hepta-4,6-diene
Generated in the absence of any reaction partner, six-
membered cycloallenes either dimerise to give derivatives
of 1,2-bismethylenecyclobutane (12 and a number of
derivatives thereof 20), oligomerise (12) or presumably poly-
merise, if dimers and oligomers are not formed in quantity
(2, 3, 4, 5, 13). As mentioned in the Introduction, an
outstanding property of many six-membered cycloallenes
is their ability to undergo cycloadditions with activated
ole®ns. Thus, a further indication for the ¯eeting existence
of 13 on treatment of 19 with KOtBu would be the observa-
tion of the respective cycloadducts. Relying on good
experience, we chose furan,2±4,6,8,9,11,16 2,5-dimethyl-
furan6,11,16 and spiro[2,4]hepta-4,6-diene21 as trapping
reagents for 13. Spiro[2,4]hepta-4,6-diene was taken instead
of cyclopenta-1,3-diene, which ranks ®rst among activated
ole®ns as to the cycloaddition rate with 122 and which was
successfully utilised also in the cases of 4,8 59 and 13,15
because KOtBu is not compatible with cyclopenta-1,3-
diene due to the acidity of the latter. Indeed, the isolation
of two or three addition products in each case testi®ed the
intermediacy of 13.
Scheme 6.
should be essentially nonpolar and should have an allene or
an allyl diradical structure.
The second possibility for the interaction of KOtBu with 13
is the deprotonation of the methylene group taking
advantage of a strong thermodynamic preference due to
the aromaticity of the arising naphth-2-yl anion (24),
which is converted into 20 on protonation by HOtBu. That
the binaphthyl 22 appeared as a product may be a mani-
festation of the nucleophilicity of 24. It could attack 13 in
much the same way as tBuO2 and, in consequence, generate
the allyl anion derivative 25. Being a better stabilised anion
than 24, 25 seems not to accept a proton, but to transfer a
hydride ion to 13, the role of which as an electrophile is thus
invoked a third time. The outcome would be 22 and the 1,2-
dihydronaphth-2-yl anion (26), which should serve as the
precursor to 23 (Scheme 6). Support for this mechanistic
scheme comes from the ®nding that 22 and 23 were formed
in similar amounts.
The reaction of 19 with KOtBu in pure furan furnished the
dihydrofuran derivatives 30±32, albeit in yields of only 2,
11 and 8%, respectively. Major products were naphthalene
(20, 41%) and phenanthrene (29, 26%). On heating in C6D6
at 1208C, 31 rearranged to 32 with high ef®ciency (Scheme
Further evidence for the intermediacy of the carbanions 24
and 26 was provided by the treatment of 19 with KOtBu in
the presence of benzophenone. Again, the major product
was naphthalene (20) and also the enol ether 21 and the
binaphthyl 22 were obtained, but the formation of the
tertiary alcohols 27 and 28 (13 and 4% yield, respectively)
Scheme 7.
Scheme 8.

4166
S. Groetsch et al. / Tetrahedron 56 (2000) 4163±4171
8). This kind of isomerisation was discovered in the case
18b (Scheme 4) and two of its methyl derivatives.16
endo-con®guration is provided by the coupling constants
J4,4aˆ4.2 Hz in 31 and 32. If 4a-H occupied the endo-
position at the oxanorbornane skeleton, the value of this
coupling constant should be close to zero according to the
Karplus±Conroy relationship. Although this criterion is
not applicable to 33 and 34, we assign them the endo-
con®guration due to the similarity of their data to those of
31 and 32. As to the structure of 30, the deciding pieces of
information originate from the enol ether moiety. The
proposed con®guration rests on the magnitude of the inter-
proton coupling constants of the cyclobutane subunit,
whereas the relative orientation of the furan and naphtha-
lene entities was determined by a H,H COSY spectrum. By
employing these tests, the structures of 35±37 could also be
elucidated completely. Even if we did not succeed in
isolating 30, 36 and 37 in a pure state, no doubts remain
as to their structures due to extremely characteristic 1H and
13C NMR spectroscopic data.
2,5-Dimethylfuran behaved like furan and gave rise to the
[412] cycloadducts 33 and 34 of 13. Since again 20 was the
dominating product (46%), only poor yields of 33 (8%) and
34 (,1%) could be obtained. The virtually quantitative
transformation of 33 to 34 by heating a solution in C6D6
at 1208C proved to be the best source for 34 (Scheme 9).
In the solution of 19 in pure spiro[2,4]hepta-4,6-diene,
KOtBu did not cause the elimination to happen. Only on
dilution of the mixture with THF, addition of 18-crown-6
and heating at 608C, 19 was consumed to produce 20, 21 and
22 as well as the pentacyclic adducts 35±37, which were
isolated in yields of only 3, 2, 1, 9, 4 and 7%, respectively
(Scheme 10).
Constitution and con®guration of 31±34 were established
by the typical NMR spectroscopic data in comparison to
those of the furan adducts of other six-membered cyclo-
allenes, which are [412] cycloadducts with no exception
and have the endo-con®guration either exclusively (2±5,
16) or predominantly (1). Conclusive evidence for the
Striking features of these cycloadditions of 13 are low yields
of all the adducts accompanied by good yields of naphtha-
lene (20), apart from the case of spiro[2,4]hepta-4,6-diene.
There, 18-crown-6 probably enhances the nucleophilicity of
the intermediate naphth-2-yl anion (24) so strongly that it
causes most of the material to polymerise. In comparison to
the Doering±Moore±Skattebùl route to 13, the urgent
question arises as to why there, the formation of 20 is negli-
gible and here it proceeds predominantly. For two reasons,
the b-elimination route starting from 19 may be put at a
disadvantage with respect to the trapping of 13 by activated
ole®ns. Firstly, the elimination of HBr takes place slowly
and, in consequence, the intermediate 13 formed is exposed
to a large excess of base, which deprotonates 13 and thus
produces 24, the precursor of naphthalene (20). Activated
ole®ns have to compete for 13 against the base. This
obstacle plays hardly any part in the generation of 13
from the dihalocyclopropane derivatives 12 by methyl-
lithium, since the bromine±lithium exchange as well as
the a-elimination of lithium halide are rapid steps.23 There-
fore, 13 never faces a large concentration of base, if methyl-
lithium is slowly added to a solution of 12. The second
reason may have its origin in the different nature of the
bases. It is well known that at a given pK value hetero
atom bases react considerably more rapid than carbon
atom bases.24 If these characteristics hold for KOtBu on
one side and methyllithium on the other, the rate constant
for the deprotonation of 13 by KOtBu could be the larger
one.
Scheme 9.
The [412] cycloadducts 31±34 meet the expectation as to
the intermediacy of 13, but the appearance of phenanthrene
(29) and the enol ether 30 throw new light on the mechanism
of interception of strained allenes by furan and on the
behaviour of certain furan adducts. Most probably, 29 is a
consecutive product of 31, which just has to eliminate one
molecule of water. This is assumed to occur under the
catalytic in¯uence of KOtBu, which could deprotonate the
rather acidic methylene group of 31, via the cyclohexa-
dienol 38 as shown in Scheme 11.
The enol ether 30 seems to emerge from the [212] cyclo-
adduct 40 of 13 with furan. Heretofore, no such products
from furan and six-membered cycloallenes are known and
Scheme 10.

S. Groetsch et al. / Tetrahedron 56 (2000) 4163±4171
4167
Scheme 11.
only [412] cycloadducts have been described.2±4,6,8,9,11,16
Recently, Tolbert et al.25 presented convincing theoretical
evidence that even [412] cycloadducts of 1 with conjugated
dienes such as furan proceed in two steps via a diradical
intermediate. Since the Woodward±Hoffmann rules favour
the stepwise formation of [212] cycloadducts, the diradical
39 should be the common intermediate en route to the
products 30±32 (Scheme 12). On closure of the four-
membered ring, conformer 39a furnishes 40, which
isomerises to give 30 by deprotonation of the methylene
group by KOtBu and reprotonation by HOtBu of the result-
ing allyl anion at the terminus belonging to the cyclobutane
moiety. The energetic preference of 30 over 40 originates
from the special strain of the methylenecyclobutane subunit
of 40 and the resonance energy of the styrene subunit of 30.
An alternative ring closure of 39a leads to the [412]
cycloadduct 32. Being engaged in the extremely mobile
equilibrium with 39a, conformer 39b seems to collapse to
the [412] cycloadduct 31 exclusively. Probably owing to its
conjugated double bond, 32 is more stable than 31. For the
rearrangement of 31 to 32 at 1208C, we again invoke the
diradical 39 (Scheme 12).
Scheme 13.
collapse of 41 to give a six-membered ring is kinetically
unfavourable because of the steric hindrance exerted by
the cyclopropane subunit or the [412] cycloadducts are
thermodynamically unstable and maintain a mobile equi-
librium with 41 even under the reaction conditions (608C).
As trapping products of 13 by spiro[2,4]hepta-4,6-diene, the
cyclobutane derivatives 35±37 came as a surprise, since the
only previous reaction of this kind, i.e. the interception of 3
by that diene led to a [412] cycloadduct in 53% yield.21 The
diradical 41 is assumed to be the common intermediate for
all products 35±37 (Scheme 13). Why no [412] cyclo-
adduct was observed may have two reasons. Either the
Resulting from the attack of the central allene carbon atom
of 13 at a terminus of the diene moiety of spiro[2,4]hepta-
4,6-diene, the conformer 41b furnishes the [212] cyclo-
adduct 35, which was isolated, on the conrotatory ring
closure. In contrast, no isolable compound emerges directly
from conformer 41a. As we infer from the products 36 and
37, it may collapse in either way, disrotatorily or conrota-
torily, and bring about the [212] cycloadducts 42 and 43,
respectively, which are converted into 36 and 37 by [1,3]
hydrogen migration, probably catalysed by KOtBu as
discussed for the pathway proposed for the formation of
30 (see Scheme 12).
Conclusions
We have demonstrated that the title intermediate 13 can be
generated from 3-bromo-1,2-dihydronaphthalene (19) by
b-elimination of HBr with KOtBu. In line with the
behaviour of other six-membered cycloallenes, 13 is subject
to trapping by KOtBu and conjugated dienes. Particularly
interesting are the products 30 and 35±37, which give
evidence for [212] cycloadditions of a strained cycloallene
with furan and spiro[2,4]hepta-4,6-diene for the ®rst time.
However, produced on the above route, 13 preferably
isomerises to naphthalene (20). This process is initiated by
KOtBu by deprotonation of 13 to furnish the naphth-2-yl
anion (24) and takes advantage of a substantial driving force
due to the aromatic character of 24. In consequence, the
Scheme 12.

4168
S. Groetsch et al. / Tetrahedron 56 (2000) 4163±4171
access to 13 via 19 has mechanistic importance, although it
is inferior to the one-pot procedure starting from indene9 for
the preparation of cycloadducts of 13 in quantity.
Enol ether 21. Colourless oil, bp 1008C (kugelrohr)/
0.01 mbar; m/z (EI) 202 (M1, 5%), 147 (12), 146 (100),
145 (29), 131 (14), 128 (11), 127 (11), 117 (24), 116 (23),
115 (25), 41 (18), 39 (11) [Found (EI): M1, 202.1352.
C14H18O requires for M1, 202.1358]; n~max (thin ®lm)/
cm21 3013 (m), 2976 (s), 2934 (s), 2887 (s), 2833 (m),
1631 (s), 1602 (m), 1570 (s), 1486 (s), 1452 (m), 1436
(m), 1426 (m), 1391 (m), 1367 (s), 1320 (m), 1270 (m),
1253 (s), 1172 (s), 1149 (s), 1106 (m), 1036 (m), 1001
(m), 907 (s), 860 (m), 821 (m), 746 (s), 670 (m); dH
(600 MHz, CDCl3) 1.48 (9H, s, tBu), 2.36 (2H, pseudo-t
of d, line distance of pseudo-tˆ8.1, J2,4ˆ0.9 Hz, 2-CH2),
2.89 (2H, br pseudo-t, line distanceˆ8.1, 1-CH2), 5.82
(1H, br s, 4-H), 6.96 (1H, br d, Jˆ7.4 Hz) and 7.13 (1H,
tdt, Jˆ7.4,1.4 and 0.7 Hz) (5-H, 6-H or 8-H, 7-H), 7.02 (1H,
td, Jˆ7.4 and 1.3 Hz) and 7.09 (1H, dm, Jˆ7.4 Hz) (7-H,
8-H or 6-H, 5-H); as far as speci®ed, the assignment is based
on a H,H COSY spectrum; dC (151 MHz, CDCl3) 28.76,
78.1 (tBu), 28.79 (C-1), 29.4 (C-2), 105.2 (C-4), 124.5,
126.9 (C-6, C-5 or C-7, C-8), 124.8, 126.4 (C-8, C-7 or
C-5, C-6), 132.2, 135.8 (C-4a, C-8a), 155.9 (C-3).
Experimental
1H and 13C NMR spectra were recorded with Bruker AC
200, AC 250 and DMX 600 instruments. As internal stan-
1
dards served CHCl3 (d 7.26) for H NMR and CDCl3 (d
77.0) for 13C NMR spectroscopy. J values are given in Hz.
The multiplicities of the signals in the 1H NMR spectra are
abbreviated by s (singlet), d (doublet), t (triplet), q (quartet),
m (multiplet), br (broad) and combinations thereof. The
multiplicities in the 13C NMR spectra were determined by
a DEPT sequence or by C,H COSY spectra. IR spectra were
recorded on a Perkin±Elmer 1605 FT-IR spectrometer.
Mass spectra were recorded on Finnigan MAT 8200 (EI
mode, 70 eV) and MAT 90 instruments (CI mode and
high resolution MS). Elemental analyses were obtained
from a LECO CHNS 932 Elemental Analyzer. Melting
points were determined by using a Ko¯er hot stage from
C. Reichert, Optische Werke A. G., Wien, Austria. For the
separation by HPLC, a Bruker-Franzen instrument LC 21C
was used.
2,20-Binaphthyl (22). See next experiment.
1
1,2-Dihydronaphthalene (23). The H NMR signals were
the same of those of a commercial sample.
All reactions were conducted in anhydrous solvents in an
atmosphere of dry nitrogen. The progress was monitored by
thin layer chromatography on pre-coated plastic sheets
Polygramw SIL G/UV254 or ALOX N/UV254 (Macherey±
Nagel, DuÈren) having 0.25 and 0.2 mm layers, respectively,
and a ¯uorescent indicator. Flash chromatography was
performed on SiO2 (0.040±0.063 mm). The eluants were
light petroleum (LP, referring to the fraction with bp
30±508C) and diethyl ether (E). Whereas the former had
to be distilled for puri®cation, the latter was used as
obtained from the supplier.
Reaction of 19 with KOtBu in the presence of benzo-
phenoneÐformation of naphth-2-yldiphenylmethanol
(27) and 1,2-dihydronaphth-2-yldiphenylmethanol (28)
To a solution of 19 (2.55 g, 12.2 mmol) and benzophenone
(4.44 g, 24.4 mmol) in THF (40 cm3) was added KOtBu
(6.85 g, 61.0 mmol). The mixture was stirred at room
temperature for 2 h and then treated with water (50 cm3)
and diethyl ether, until two layers resulted. These were
separated and the aqueous layer was extracted with diethyl
ether (3£30 cm3). The combined organic layers were dried
with MgSO4 and concentrated in vacuo. The residue was
puri®ed by ¯ash chromatography (SiO2, LP±E 20:1 for the
®rst 260 cm3 of eluate, 10:1 for the next 220 cm3, 5:1 for the
next 100 cm3 and ®nally 2:1) to give, in the order of elution,
naphthalene 20 (800 mg, 51%), a 1:2 mixture (120 mg) of
20 (2%) and 21 (4%), 22 (120 mg, 4%), a 3:1 mixture
(190 mg) of 28 (4%) and benzophenone and 27 (500 mg,
13%).
Reaction of 3-bromo-1,2-dihydronaphthalene (19) with
potassium tert-butoxide (KOtBu)
To a solution of 19 (1.614 g, 7.72 mmol) in THF (40 cm3)
was added KOtBu (1.970 g, 17.6 mmol). The mixture was
stirred at 208C and turned brown within 24 h. It was then
cautiously treated with water (5 cm3). Diethyl ether was
admixed until two layers resulted, which were separated.
The aqueous layer was extracted with diethyl ether
(3£10 cm3). The combined organic layers were dried with
MgSO4 and concentrated in vacuo to give a somewhat
gummy solid (1.147 g), which was shown to consist mainly
of a 73:22:3:2 mixture of naphthalene (20), 3-tert-butoxy-
1,2-dihydronaphthalene (21), 2,20-binaphthyl (22) and 1,2-
dihydronaphthalene (23) by 1H NMR spectroscopy. By
using diethyl malonate as internal standard the yield was
determined to be 92%. On employing a molar ratio of 19:
KOtBuˆ1:5 instead of 1.0:2.3 (see above), the product ratio
changed to 84:2:2:2.
2,20-Binaphthyl (22). Colourless crystals, mp 1878C (Ref.
26, 187±1898C); dH (600 MHz, CDCl3) 7.51, 7.53 (2£1H,
2£ddd, J6,7ˆ6.8 Hz, Jˆ8.0 and 1.4 Hz, 6-H, 7-H), 7.893
(1H, dd, J3,4ˆ8.4 Hz, J1,3ˆ1.8 Hz, 3-H), 7.895, 7.95
(2£1H, 2£br d, J5,6ˆJ7,8ˆ8.0 Hz, 5-H, 8-H), 7.97 (1H, br
d, J3,4ˆ8.4 Hz, 4-H), 8.18 (1H, br d, J1,3ˆ1.8 Hz, 1-H); dC
(151 MHz, CDCl3) 125.7, 127.7, 128.2 (C-3, C-5, C-8),
126.0, 126.3 (C-6, C-7), 126.1 (C-1), 128.5 (C-4), 132.7,
133.7 (C-4a, C-8a), 138.4 (C-2); in Ref. 26, two carbon
signals are missing and that at 148.5 does not originate
from 22.
The crude product obtained from 2.55 g of 19 (12.2 mmol)
was subjected to ¯ash chromatography (SiO2, LP for the
®rst 1140 cm3 of eluate and ®nally LP±E 20:1). The enol
ether 21 (160 mg, 6%) was eluted after the hydrocarbons.
Alcohol 27. Colourless solid, mp 1158C (Ref. 18, 115.58C);
we prepared an authentic sample by the reaction of naphth-
2-yl magnesium bromide with benzophenone; dH
(600 MHz, CDCl3) 2.90 (1H, br s, OH), 7.27±7.35 (10H,

S. Groetsch et al. / Tetrahedron 56 (2000) 4163±4171
4169
m, C6H5), 7.44±7.50 (3H, m, 3-H, 6-H, 7-H), 7.70 (1H, br d,
J1,3ˆ1.5 Hz, 1-H), 7.75, 7.83 (2£1H, 2£br d, Jˆ7.4 Hz,
5-H, 8-H), 7.79 (1H, br d, J3,4ˆ8.8 Hz, 4-H); dC
(151 MHz, CDCl3) 82.2, 126.1, 126.2, 126.3, 126.5,
127.4 (high intensity), 127.5, 127.7, 127.9, 128.0 (very
high intensity), 128.4, 132.5 and 132.8 (C-4a, C-8a),
144.2 (C-2), 146.7 (C-10).
to the extent of 10±20%; m/z (EI) 196 (M1, 2%), 195 (1),
165 (5), 129 (10), 128 (100), 127 (7), 102 (7), 63 (5), 51 (6),
39 (7) [Found (EI): (M±H)1, 195.0810. C14H12O requires
for (M±H)1, 195.0810]; dH (600 MHz, CDCl3) 3.52 (1H,
dddt, J6a,9bˆ10.7 Hz, J6,6aˆ5.4 Hz, J6a,6bˆ4.0 Hz, average
of J5,6a and J6a,9aˆ1.4 Hz, 6a-H), 3.57 (1H, dtt, J6b,9a
ˆ
7.6 Hz, average of J9a,9b and J9,9aˆ3.1 Hz, average of J8,9a
and J6a,9aˆ1.4 Hz, 9a-H), 3.65 (1H, br dd, J6a,9bˆ10.7 Hz,
J9a,9bˆ3.4 Hz, 9b-H), 4.88 (1H, ddd, J6b,9aˆ7.6 Hz,
J6a,6bˆ4.0 Hz, J6b,9bˆ0.8 Hz, 6b-H), 5.34 (1H, t, J8,9ˆ
Alcohol 28. The NMR signals were the same as those of a
pure authentic sample, which was prepared by reaction of
1,2-dihydronaphth-2-yl potassium in liquid ammonia19 with
benzophenone. The crude product was submitted to ¯ash
chromatography (SiO2, LP±E 10:1 for the ®rst 750 cm3 of
eluate and ®nally 5:1) to give a mixture of naphthalene,
benzophenone and 28, which was separated by HPLC
(PROGIDY 5u ODS3 100A, 250£21.2 mm, methanol±
water 9:1). Alcohol 28 (12% yield) was eluted as the last
component, yellowish crystals, mp 116±1188C; m/z (EI)
294 (M1±H2O, 5%), 215 (6), 184 (15), 183 (100), 130
(7), 129 (10), 128 (18), 127 (6), 106 (8), 105 (100), 78
(5), 77 (43), 51 (10), 40 (7) [Found (CI, CH4): M1H1,
313.1594. C23H20O requires for M1H1, 313.1592]; dH
(600 MHz, CDCl3) 2.22 (1H, s, OH), 2.65 (1H, dd, J1,1ˆ
16.0 Hz, J1,2ˆ7.2 Hz) and 2.91 (1H, dd, J1,1ˆ16.0 Hz,
J1,2ˆ11.7 Hz) (1-CH2), 3.81 (1H, ddt, J1,2ˆ11.7 and
7.2 Hz, average of J2,3 and J2,4ˆ2.8 Hz, 2-H), 5.77 (1H,
dd, J3,4ˆ9.8 Hz, Jˆ3.1 Hz) and 6.58 (1H, dd, J3,4ˆ9.8 Hz,
Jˆ2.4 Hz) (3-H, 4-H), 6.99 (1H, br d, Jˆ7.1 Hz) and 7.03
(1H, dd, Jˆ7.2 and 1.3 Hz) (5-H, 8-H), 7.11 (1H, td,
J9,9aˆ2.8 Hz, 9-H), 5.85 (1H, dd, J5,6ˆ9.8 Hz, J6,6a
ˆ
5.4 Hz, 6-H), 6.33 (1H, br d, J5,6ˆ9.8 Hz, 5-H), 6.43 (1H,
dd, J8,9ˆ2.8 Hz, J8,9aˆ1.5 Hz, 8-H), 6.97 (1H, dd, Jˆ7.3
and 1.5 Hz) and 7.00 (1H, dm, Jˆ6.9 Hz) (1-H, 4-H), 7.10
(1H, tm, Jˆ7.4 Hz) and 7.13 (1H, td, Jˆ7.4 and 1.6 Hz)
(2-H, 3-H); dC (151 MHz, CDCl3) 41.2 (C-9b), 42.8
(C-6a), 55.8 (C-9a), 86.6 (C-6b), 106.0 (C-9), 125.2 (C-6),
126.7, 127.9 (C-2, C-3), 127.2 (C-5), 127.3, 128.1 (C-1,
C-4), 131.5, 135.8 (C-4a, C-9c), 146.7 (C-8).
Compound 31. Brownish crystals, mp 90±928C (Found
85.24; H, 6.45. C14H12O requires C, 85.68; 6.16%); m/z
(EI) 196 (M1, 58%), 195 (68), 181 (23), 179 (56), 178
(44), 177 (20), 167 (100), 166 (36), 165 (100), 153 (21),
152 (72), 128 (48), 115 (27); dH (600 MHz, CDCl3) 3.28
(1H, ddd, J9,9ˆ18.5 Hz, J9,10ˆ6.4 Hz, J4a,9ˆ1.7 Hz, 9b-H),
3.37 (1H, ddm, J9,9ˆ18.5 Hz, J4a,9ˆ6.5 Hz, 9a-H), 3.47
(1H, m, 4a-H), 5.26 (1H, br d, J1,2ˆ1.9 Hz, 1-H), 5.61
(1H, ddt, J4,4aˆ4.2 Hz, J3,4ˆ1.6 Hz, average of J1,4 and
J4,10ˆ0.7 Hz, 4-H), 5.85 (1H, dddt, J9,10ˆ6.4 and 2.0 Hz,
J4a,10ˆ2.6 Hz, average of J1,10 and J4,10ˆ0.9 Hz, 10-H),
6.18 (1H, dd, J2,3ˆ5.7 Hz, J3,4ˆ1.6 Hz, 3-H), 6.27 (1H,
dd, J2,3ˆ5.7 Hz, J1,2ˆ1.9 Hz, 2-H), 7.08 (1H, dm,
J5,6ˆ7.7 Hz, 5-H), 7.13±7.19 (3H, m, 6-H, 7-H, 8-H), the
assignment is based on a H,H COSY spectrum; dC
(151 MHz, CDCl3) 32.1 (C-9), 44.4 (C-4a), 80.0 (C-1),
80.4 (C-4), 113.7 (C-10), 124.0 (C-5), 125.9, 126.0, 127.0
(C-6, C-7, C-8), 131.5 (C-3), 135.3 (C-2), 137.7, 138.4,
141.3 (C-4b, C-8a, C-10a).
3
average of two Jˆ7.3 Hz, Jˆ1.5 Hz) and 7.13 (1H, br t,
average of two 3Jˆ7.3 Hz) (6-H, 7-H), 7.219, 7.222 (2£1H,
2£tt, 2£p-H of C6H5), 7.323, 7.334 (2£2H, 2£m, 2£m-H of
C6H5), 7.50, 7.56 (2£2H, 2£m, 2£o-H of C6H5); dC
(151 MHz, CDCl3) 28.8 (C-1), 42.7 (C-2), 80.0 (COH),
125.6, 126.0 (2£o-C of C6H5), 126.1 (C-5 or C-8), 126.5,
127.6 (C-6, C-7), 126.6, 126.8 (2£p-C of C6H5), 127.8,
127.9 (C-8 or C-5 and C-3 or C-4), 128.3, 128.4 (2£m-C
of C6H5), 131.0 (C-4 or C-3), 133.1, 135.0 (C-4a, C-8a),
145.3 (C-2), 145.9 (2£i-C of C6H5).
Compound 32. Brownish crystals, mp 868C; m/z (EI) 196
(M1, 61%), 195 (64), 181 (20), 179 (47), 178 (32), 167
(100), 166 (31), 165 (93), 153 (21), 152 (70), 128 (40),
115 (21) [Found (EI): (M±H)1, 195.0812. C14H12O requires
for (M±H)1, 195.0810]; dH (600 MHz, CDCl3) 2.25 (1H, br
dd, J4a,10ˆ16.9 Hz, J10,10ˆ14.4 Hz, 10b-H), 2.85 (1H, dd,
J10,10ˆ14.4 Hz, J4a,10ˆ5.9, 10a-H), 3.10 (1H, dddd,
J4a,10ˆ16.9 and 5.9 Hz, J4,4aˆ4.2 Hz, J4a,9ˆ2.5 Hz, 4a-H),
Reaction of 19 with KOtBu in furanÐformation of
(1a,4a,4aa)-1,4,4a,9-tetrahydro-1,4-epoxyphenanthrene
(31), (1a,4a,4aa)-1,4,4a,10-tetrahydro-1,4-epoxy-
anthracene (32) and (6aa,6bb,9ab,9ba)-6a,6b,9a,9b-
tetrahydronaphtho[10,20:3,4]cyclobuta[1,2-b]furan (30)
To a stirred solution of 19 (4.00 g, 19.1 mmol) in freshly
distilled furan (60 cm3) was added KOtBu (7.69 g,
68.5 mmol) in small portions over a period of 1 h at 208C.
After stirring had been continued for 3 h, more furan
(20 cm3) was added to the mixture, which was now stirred
for 24 h. Then the treatment with water (30 cm3) ensued,
followed by the separation of the layers and extraction of the
aqueous layer with diethyl ether (3£30 cm3). The combined
organic layers were dried with MgSO4 and concentrated in
vacuo. The residue was puri®ed by ¯ash chromatography
(SiO2, deactivated by ammonia, LP for the ®rst 640 cm3 of
eluate, LP±E 20:1 for the next 400 cm3 and ®nally 5:1) to
give, in the order of elution, naphthalene (20) (1.00 g, 41%),
phenanthrene (29) (890 mg, 26%), 30 (85 mg, 2%), 31
(410 mg, 11%), and 32 (300 mg, 8%).
5.15 (1H, br d, J1,2ˆ1.9 Hz, 1-H), 5.23 (1H, br d, J4,4a
ˆ
4.2 Hz, 4-H), 6.21 (1H, dd, J2,3ˆ5.7 Hz, J3,4ˆ1.6 Hz, 3-
H), 6.31 (1H, d, J4a,9ˆ2.5 Hz, 9-H), 6.73 (1H, dd, J2,3ˆ
5.7 Hz, J1,2ˆ1.9 Hz, 2-H), 6.98 (2H, br d, J5,6ˆ
J7,8ˆ7.4 Hz, 5-H, 8-H), 7.05 (1H, td, Jˆ7.4 and 1.4 Hz)
and 7.10 (1H, tt, Jˆ7.4 and 1.2 Hz) (6-H, 7-H); dC
(151 MHz, CDCl3) 33.3 (C-10), 40.8 (C-4a), 79.9 (C-1),
81.7 (C-4), 116.7 (C-9), 126.4, 128.0 (C-5, C-8), 126.9 (2
C, C-6, C-7), 133.6 (C-3), 139.1 (C-2), 134.1, 135.3 (C-8a,
C-10a), 146.3 (C-9a).
Rearrangement of 31 to 32
A solution of a 60:40 mixture of 32 and 31 (50 mg) in C6D6
Compound 30. Green ¯uorescing oil, containing impurities
(0.7 cm3), contained in an NMR tube, was degassed by

4170
S. Groetsch et al. / Tetrahedron 56 (2000) 4163±4171
several freeze±pump±thaw cycles. The NMR tube was then
sealed and heated at 1208C for 4 d. Analysed by H NMR
spectroscopy, the ratio of mixture had turned to 95:5 in
favour of 32. By using the signals of the aromatic protons
as internal standard, the yield was determined to be close to
quantitative.
2.28 (1H, dd, J4a,10ˆ16.0 Hz, J10,10ˆ14.4 Hz, 10b-H), 2.80
(1H, dd, J10,10ˆ14.4 Hz, J4a,10ˆ5.9 Hz, 10a-H), 2.88 (1H,
ddd, J4a,10ˆ16.0 and 5.9 Hz, J4a,9ˆ2.4 Hz, 4a-H), 6.00, 6.50
(2£1H, 2£d, J2,3ˆ5.5 Hz, 2-H, 3-H), 6.18 (1H, d,
J4a,9ˆ2.4 Hz, 9-H), 7.00 (2H, br d, Jˆ7.4 Hz, 5-H, 8-H),
7.05 (1H, td, Jˆ7.4 and 1.3 Hz) and 7.10 (1H, tt, Jˆ7.4
and 1.1 Hz) (6-H, 7-H); dC (151 MHz, CDCl3) 14.7, 17.9
(1-CH3, 4-CH3), 32.9 (C-10), 48.1 (C-4a), 86.7, 88.5 (C-1,
C-4), 115.0 (C-9), 126.3, 126.8, 126.9, 128.0 (C-5, C-6, C-7,
C-8), 134.1, 135.1, (C-8a, C-10a), 137.6, 142.8 (C-2, C-3),
152.7 (C-9a).
1
Reaction of 19 with KOtBu in 2,5-dimethylfuranÐ
formation of (1a,4a,4aa)-1,4,4a,9-tetrahydro-1,4-
dimethyl-1,4-epoxyphenanthrene (33) and (1a,4a,4aa)-
1,4,4a,10-tetrahydro-1,4-dimethyl-1,4-epoxyanthracene
(34)
Reaction of 19 with KOtBu in the presence of spiro-
[2,4]hepta-4,6-dieneÐformation of (3aa,3bb,9ba)-3a,
3b,4,9b-tetrahydrospiro[cyclopenta[1,2]cyclobuta[3,4-
b]naphthalene-1,10-cyclopropane] (35), (6aa,6ba,9aa,9ba)-
6a,6b,9a,9b-tetrahydrospiro[cyclopenta[1,2]cyclobuta[3,4-
a]naphthalene-7,10-cyclopropane] (36) and (6aa,6bb,
9ab,9ba)-6a,6b,9a,9b-tetrahydrospiro[cyclopenta[1,2]-
cyclobuta[3,4-a]naphthalene-7,10-cyclopropane] (37)
A mixture of 19 (2.00 g, 9.57 mmol) and KOtBu (4.00 g,
35.6 mmol) in 2,5-dimethylfuran (30 cm3) was stirred at
room temperature for 20 h. Water (30 cm3) was then
cautiously added to the mixture with continued stirring.
The resulting two layers were separated and the aqueous
layer was extracted with diethyl ether (3£30 cm3). After
drying with MgSO4, the combined organic layers were
concentrated in vacuo. By ¯ash chromatography (SiO2, LP
for the ®rst 50 cm3 of eluate, LP±E 20:1 for the next 340
cm3 and ®nally 10:1), the residue was puri®ed to give, in the
order of elution, naphthalene (20) (560 mg, 46%), 33
(160 mg, 8%) and a 3:1 mixture (20 mg, 1%) of 33 and 34.
A stirred mixture of 19 (1.90 g, 9.09 mmol), spiro[2,4]-
hepta-4,6-diene (5 cm3), KOtBu (3.00 g, 26.7 mmol) and
18-crown-6 (2.39 g, 9.04 mmol) in THF (50 cm3) was
heated at 608C. After 2 h and after 4 h, further KOtBu
(1.00 g, 8.9 mmol each time) was added. After 6 h, the
mixture was hydrolysed (50 cm3) cautiously and diethyl
ether was added until two layers resulted. The aqueous
layer was extracted with diethyl ether (3£30 cm3), the
combined organic layers were dried with MgSO4 and
concentrated in vacuo. The residue was puri®ed by ¯ash
chromatography (SiO2, LP±E 20: 1 for the ®rst 640 cm3
of eluate and ®nally 15:1) to give, in the order of elution,
37 (140 mg, 7%), 35 (170 mg, 8%), 20 (30 mg, 3%) and a
fourth fraction, which, for its part, was submitted to ¯ash
chromatography (SiO2, LP±E 10:1). It afforded 21 (30 mg,
2%) and 22 (30 mg, 1%) as the second and third fraction,
whereas the ®rst fraction gave 36 (80 mg, 4%) in third ¯ash
chromatography step (SiO2, LP).
Compound 33. Yellow oil; m/z (EI) 224 (M1, 4%), 209 (9),
182 (16), 181 (100), 179 (8), 178 (10), 167 (10), 166 (59),
165 (62), 153 (10), 152 (11), 141(8), 128 (12), 115 (10), 89
(7), 63 (8), 43 (43) [Found (EI): M1, 224.1200. C16H16O
requires for M1, 224.1201]; dH (600 MHz, CDCl3) 1.68
(3H, s, 1-CH3), 2.03 (3H, s, 4-CH3), 3.21 (1H, br d,
J4a,9ˆ6.2 Hz, 4a-H), 3.29 (1H, ddd, J9,9ˆ18.3 Hz,
J9,10ˆ6.2 Hz, J4a,9ˆ1.6 Hz, 9b-H), 3.34 (1H, br dd,
J9,9ˆ18.3 Hz, J4a,9ˆ6.2 Hz, 9a-H), 5.73 (1H, dt, J9,10ˆ6.2
and 2.4 Hz, J4a,10ˆ2.4 Hz, 10-H), 6.01, 6.10 (2£1H, 2£d,
J2,3ˆ5.4 Hz, 2-H, 3-H), 7.12±7.19 (3H, m) and 7.25 (1H, br
d, Jˆ7.5 Hz) (5-H, 6-H, 7-H, 8-H), as far as speci®ed, the
assignment is based on a H,H COSY spectrum; dC
(151 MHz, CDCl3) 15.4 (1-CH3), 20.3 (4-CH3), 32.4
(C-9), 51.2 (C-4a), 85.9, 87.4 (C-1, C-4), 112.1 (C-10),
123.0 (C-5 or C-8), 125.8, 125.9, 127.2 (C-6, C-7, C-8 or
C-5), 135.7, 138.80 (C-2, C-3), 138.3, 138.76, 148.2 (C-4b,
C-8a, 10a).
Compound 35. Colourless crystals, mp 748C; m/z (EI) 220
(M1, 74%), 219 (29), 205 (57), 204 (31), 203 (34), 202 (27),
192 (46), 191 (51), 190 (24), 189 (32), 179 (26), 178 (35),
165 (38), 142 (22), 141 (100), 128 (40), 91 (23) [Found (EI):
M1, 220.1252. C17H16 requires for M1, 220.1252]; n~max
(KBr)/cm21 3067 (w), 2991 (w), 2937 (m), 2927 (m),
2873 (m), 1664 (w), 1596 (w), 1476 (w), 1450 (w), 1428
(w), 968 (w), 938 (m), 892 (m), 845 (w), 838 (w), 778 (m),
743 (s), 698 (m), 669 (m), 601 (w), 573 (w), 544 (w), 456
(w); dH (600 MHz, CDCl3) 0.63±0.71 (2H, m, 20-H, 30-H),
0.85±0.93 (2H, m, 20-H, 30-H), 2.72±2.82 (2H, m, 3b-H,
4-H), 2.84 (1H, m, 4-H), 3.21 (1H, ddd, J3a,9bˆ6.7 Hz,
Compound 34. See next experiment.
Rearrangement of 33 to 34
A solution of a 87:13 mixture of 33 and 34 (50 mg) in C6D6
(0.7 cm3), contained in an NMR tube, was degassed by
several freeze±pump±thaw cycles. The NMR tube was
then sealed and heated at 1208C for 4 d. As analysed by
1H NMR spectroscopy, 33 had converted into 34. By
using the signals of the aromatic protons as internal stan-
dard, the yield was determined to be close to quantitative.
The concentration of the solution in vacuo led to virtually
pure 34 as a yellow oil; m/z (EI) 224 (M1, 7%), 209 (7), 182
(16), 181 (100), 179 (10), 178 (10), 167 (10), 166 (63), 165
(70), 164 (7), 163 (7), 153 (12), 152 (11), 141 (8), 128 (7),
127 (7), 115 (10), 89 (7), 82 (7), 63 (7), 43 (26) [Found (EI):
M1, 224.1202. C16H16O requires for M1, 224.1201]; dH
(600 MHz, CDCl3) 1.66, 1.72 (2£3H, 2£s, 1-CH3, 4-CH3),
J3a,3bˆ3.9 Hz, J3,3aˆ2.7 Hz, 3a-H), 3.42 (1H, br d, J3a,9b
ˆ
6.7 Hz, 9b-H), 5.34 (1H, d, J2,3ˆ5.5 Hz) and 5.90 (1H, dd,
Jˆ5.5 and 2.7 Hz) (2-H, 3-H), 6.12 (1H, br s, 9-H), 7.01
(1H, br d, Jˆ7.3 Hz) and 7.12 (1H, br t, Jˆ7.3 Hz) (5-H,
6-H or 8-H, 7-H), 7.04 (1H, br td, Jˆ7.3 and 1.2 Hz) and
7.07 (1H, br d, Jˆ7.3 Hz) (7-H, 8-H or 6-H, 5-H), the
assignment is based on a H,H COSY spectrum; dC
(151 MHz, CDCl3) 10.8, 15.7 (C-20, C-30), 32.5 (C-1),
34.0 (C-4), 45.7 (C-3b), 50.2 (C-3a), 51.4 (C-9b), 117.6
(C-9), 125.6, 126.6 (C-5, C-6 or C-8 or C-7), 125.9, 128.0

S. Groetsch et al. / Tetrahedron 56 (2000) 4163±4171
4171
(C-7, C-8 or C-6, C-5), 131.5, 140.1 (C-2, C-3), 135.3, 135.5
(C-4a, C-8a), 146.4 (C-9a).
References
1. Part 14: Christl, M.; Groetsch, S.; GuÈnther, K. Angew. Chem.
2000, 112, in press; Angew. Chem., Int. Ed. 2000, 39, in press.
2. Johnson, R. P. Chem. Rev. 1989, 89, 1111±1124.
3. Schreck, M.; Christl, M. Angew. Chem. 1987, 99, 720±721;
Angew. Chem., Int. Ed. Engl. 1987, 26, 690±692.
4. Schlosser, M. Yuki Gosei Kagaku Kyokaishi 1988, 46, 528±
539. Ruzziconi, R.; Naruse, Y.; Schlosser, M. Tetrahedron 1991,
47, 4603±4610.
Compound 36. Yellow crystals, mp 728C, containing
impurities to the extent of 10±20%; m/z (EI) 220 (M1,
22%), 205 (16), 192 (10), 191 (14), 165 (11), 141 (26),
129 (14), 128 (100), 92 (56), 91 (52) [Found (EI): M1,
220.1247. C17H16 requires for M1, 220.1252]; dH
(600 MHz, CDCl3) 0.48 (1H, ddd, Jcisˆ9.6 Hz, Jtrans
ˆ
6.3 Hz, Jgemˆ4.3 Hz) and 0.52 (1H, ddd, Jcisˆ9.2 Hz,
Jtransˆ6.2 Hz, Jgemˆ4.3 Hz) (20-CH2 or 30-CH2), 0.84 (1H,
ddd, Jcisˆ9.2 Hz, Jtransˆ6.3 Hz, Jgemˆ4.9 Hz) and 0.94 (1H,
ddd, Jcisˆ9.6 Hz, Jtransˆ6.2 Hz, Jgemˆ4.9 Hz) (30-CH2 or 20-
CH2), 3.00 (1H, dd, J6a,9bˆ9.0 Hz, J9a,9bˆ6.9 Hz, 9b-H),
5. Christl, M.; Braun, M. In Strain and Its Implications in Organic
Chemistry; de Meijere, A., Blechert, S., Eds.; Kluwer: Dordrecht,
1989, pp 121±131.
6. Christl, M.; Braun, M. Chem. Ber. 1989, 122, 1939±1946.
Â
7. Jamart-Gregoire, B.; Grand, V.; Ianelli, S.; Nardelli, M.;
Á
Caubere, P. Tetrahedron Lett. 1990, 31, 7603±7606. Jamart-
Â
Gregoire, B.; Mercier-Girardot, S.; Ianelli, S.; Nardelli, M.;
3.53 (1H, dddt, J6a,6bˆ10.9 Hz, J6a,9bˆ9.0 Hz, J6,6a
ˆ
4.2 Hz, average of J5,6a and J6a,9aˆ1.9 Hz, 6a-H), 3.82
(1H, ddq, J6b,9aˆ8.8 Hz, J9a,9bˆ6.9 Hz, average of J6a,9a
Á
Caubere, P. Tetrahedron 1995, 51, 1973±1984.
and J8,9a and J9,9aˆ1.9 Hz, 9a-H), 3.97 (1H, dd, J6a,6b
ˆ
10.9 Hz, J6b,9aˆ8.8 Hz, 6b-H), 5.28 (1H, br d, J8,9ˆ
5.5 Hz) and 5.36 (1H, dd, Jˆ5.5 and 2.4 Hz) (8-H, 9-H),
5.96 (1H, dd J5,6ˆ10.0 Hz, J6,6aˆ4.2 Hz, 6-H), 6.17 (1H, dd,
J5,6ˆ10.0 Hz, J5,6aˆ2.1 Hz, 5-H), 6.87, 6.88 (2£1H, 2£dd,
Jˆca. 7 and 2.1 Hz, 1-H, 4-H), 7.03±7.08 (2H, m, 2-H,
3-H), the assignment is based on a H,H COSY spectrum;
dC (151 MHz, CDCl3) 11.0, 13.5 (C-20 C-30), 30.7 (C-7),
37.6 (C-6a), 39.0 (C-6b), 52.1 (C-9b), 54.7 (C-9a), 126.4,
127.8 (C-2, C-3), 126.7, 127.4 (C-1, C-4), 127.0 (C-5),
130.0, 140.7 (C-8, C-9), 130.1 (C-6), 133.0, 133.8 (C-4a,
C-9c).
8. Christl, M.; Braun, M.; Wolz, E.; Wagner, W. Chem. Ber. 1994,
127, 1137±1142.
9. Christl, M.; Braun, M.; MuÈller, G. Angew. Chem. 1992, 104,
471±473; Angew. Chem., Int. Ed. Engl. 1992, 31, 473±476.
10. (a) Roth, W. R.; Hopf, H.; Horn, C. Chem. Ber. 1994, 127,
1765±1779. (b) Hopf, H.; Berger, H.; Zimmermann, G.; NuÈchter,
U.; Jones, P. G.; Dix, I. Angew. Chem. 1997, 109, 1236±1238;
Angew. Chem., Int. Ed. Engl. 1997, 36, 1187±1190.
11. Christl, M.; Groetsch, S. Eur. J. Org. Chem. 2000, 1871±1874.
12. Emanuel, C. J.; Shevlin, P. B. J. Am. Chem. Soc. 1994, 116,
5991±5992. Pan, W.; Shevlin, P. B. J. Am. Chem. Soc. 1997, 119,
5091±5094.
Compound 37. Yellow crystals, mp 648C, containing impu-
rities to the extent of 10±20%; m/z (EI) 220 (M1, 2%), 205
(4), 191 (3), 141 (4), 129 (11), 128 (100), 127 (6), 93 (4), 92
(60), 91 (50), 65 (4) [Found (EI): M1, 220.1253. C17H16
requires for M1, 220.1252]; dH (600 MHz, CDCl3) 0.62
(1H, m) and 0.70±0.77 (2H, m) and 0.82 (1H, m) (20-CH2,
30-CH2), 2.53 (1H, t, average of J6a,6b and J6b,9aˆ6.5 Hz,
6b-H), 3.19 (1H, br dt, J6a,9bˆ10.2 Hz, average of J6,6a and
J6a,6bˆ5.5 Hz, 6a-H), 3.48 (1H, dd, J6a,9bˆ10.2 Hz,
J9a,9bˆ3.4 Hz, 9b-H), 3.56 (1H, m, 9a-H), 5.34 (1H, d,
J8,9ˆ5.4 Hz) and 5.97 (1H, dd, Jˆ5.4 and 2.5 Hz) (8-H,
9-H), 5.73 (1H, dd, J5,6ˆ9.7 Hz, J6,6aˆ5.3 Hz, 6-H), 6.22
(1H, d, J5,6ˆ9.7 Hz, 5-H), 6.95, 7.01 (2£1H, 2£br d,
Jˆ7.3 Hz, 1-H, 4-H), 7.09, 7.11 (2£1H, 2£tm, Jˆ7.3 Hz,
2-H, 3-H), the assignment is based on a H,H COSY
spectrum; dC (151 MHz, CDCl3) 8.4, 15.6 (C-20, C-30),
35.1 (C-7), 37.7 (C-6a), 40.6 (C-9b), 53.6 (C-6b), 57.9
(C-9a), 125.3 (C-5), 126.3, 127.7 (C-2, C-3), 126.9, 128.1
(C-1, C-4), 129.0 (C-6), 132.1, 137.2 (C-4a, C-9c), 132.5,
138.3 (C-8, C-9).
13. Pan, W.; Balci, M.; Shevlin, P. B. J. Am. Chem. Soc. 1997,
119, 5035±5036.
14. Miller, B.; Shi, X. J. Am. Chem. Soc. 1987, 109, 578±579.
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15. MuÈller, G. Dissertation, Universitat Wurzburg, 1993.
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17. Adamczyk, M.; Watt, D. S.; Netzel, D. A. J. Org. Chem. 1984,
49, 4226±4237.
18. Ullmann, F.; Mourawiew-Winigradoff, A. Chem. Ber. 1905,
38, 2213±2219.
19. de Vlieger, J. J.; Kieboom, A. P. G.; van Bekkum, H. J. Org.
Chem. 1986, 51, 1389±1392.
20. Christl, M.; Schreck, M. Chem. Ber. 1987, 120, 915±920;
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Fischer, T. Diplomarbeit, Universitat Wurzburg, 1993; Moigno,
D. Diplomarbeit, Universitat Wurzburg, 1996.
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21. Braun, M. Dissertation, Universitat Wurzburg, 1990.
22. Bottini, A. T.; Hilton, L. L.; Plott, J. Tetrahedron 1975, 31,
1997±2001.
23. Boche, G.; Walborsky, H. M. Cyclopropane Derived Reactive
Intermediates, Wiley: Chichester, 1990 pp. 175±205.
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We are grateful to the Fonds der Chemischen Industrie and
the Deutsche Forschungsgemeinschaft for support.