Reactivity of the 5-hydroacenaphthylene anion towards electrophiles

Article abstract of DOI:10.1002/(sici)1099-0690(199809)1998:9<1907::aid-ejoc1907>3.0.co;2-s

The dianion of acenaphthylene can be converted into the 5-hydroanion by protonation with one equivalent of methanol. Subsequent reaction with electrophiles such as allyl bromide and propargyl bromide occurs selectively at position 1, resulting in the formation of the novel 1-allylacenaphthene and 1-propargylacenaphthene. In addition to what was observed in the case of methyl iodide, the hitherto unknown 1,1-dialkylated acenaphthene derivatives are formed as minor products; probably the lower reactivity of the unsaturated bromides is responsible for this side reaction. From the products of the reactions with 3,3-dimethylallyl bromide and (bromomethyl)cyclopropane the mechanism was found to be S_N2. Reaction of the hydroanion with benzyl bromide takes place at position 1 as well as at position 2a. The reactivity of carbon 2a towards the soft electrophile benzyl bromide is attributed to the high HOMO coefficient at this position.

Full text of DOI:10.1002/(sici)1099-0690(199809)1998:9<1907::aid-ejoc1907>3.0.co;2-s

FULL PAPER
Reactivity of the 5-Hydroacenaphthylene Anion towards Electrophiles
Marcia E. Van Loo, Johan Lugtenburg, and Jan Cornelisse*
Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University,
P. O. Box 9502, NL-2300 RA Leiden, The Netherlands
Fax: (internat.) ϩ 31-71/5274488
E-mail: cornelisse@rulgca.leidenuniv.nl
Received April 2, 1998
Keywords: Reductive alkylation / Acenaphthylene / Carbanions / Polycycles
The dianion of acenaphthylene can be converted into the 5-
unsaturated bromides is responsible for this side reaction.
hydroanion by protonation with one equivalent of methanol. From the products of the reactions with 3,3-dimethylallyl
Subsequent reaction with electrophiles such as allyl bromide
bromide and (bromomethyl)cyclopropane the mechanism
and propargyl bromide occurs selectively at position 1, was found to be SN2. Reaction of the hydroanion with benzyl
resulting in the formation of the novel 1-allylacenaphthene
and 1-propargylacenaphthene. In addition to what was
observed in the case of methyl iodide, the hitherto unknown
1,1-dialkylated acenaphthene derivatives are formed as
minor products; probably the lower reactivity of the
bromide takes place at position 1 as well as at position 2a.
The reactivity of carbon 2a towards the soft electrophile
benzyl bromide is attributed to the high HOMO coefficient
at this position.
Introduction
Scheme 2. Reaction of the acenaphthylene dianion with electrophiles
Polycyclic aromatic hydrocarbons (PAH) can be easily
substituted by reductive alkylation. The advantage of re-
ductive alkylation with respect to electrophilic aromatic
substitution is that relatively unreactive electrophiles can be
used. A second important advantage is that the reactions
often are very selective. In the Birch-like reductive alky-
lation PAH are converted into their anions using sodium in
a mixture of liquid ammonia and THF. Under these con-
ditions the PAH can give dianions or hydroanions, de-
pending on the size and reactivity of the PAH (Scheme
1).[1][2][3] A more convenient procedure is the preparation
of the dianion in pure THF, using sodium and ultrasonic vi-
bration.
Scheme 1. Reduction scheme for polycyclic aromatic hydrocarbons
Reaction of the hydroanion with one equivalent of
methyl iodide results in the formation of 1-methyl-1,5-dihy-
droacenaphthylene in more than 90% yield.[10] Treatment
with a few drops of HCl in acetone gives rearrangement to
the more stable 1-methylacenaphthene.
In the present work we use the 5-hydroacenaphthylene
anion in reactions with allyl bromide, 3,3-dimethylallyl bro-
mide, propargyl bromide, and (bromomethyl)cyclopropane.
This extension to allylic systems leads to introduction of
functional groups at position 1 in acenaphthene and to the
synthesis of seven novel compounds. Another reason for
using these electrophiles is the possibility to study the
mechanism of the reaction of the 5-hydroacenaphthylene
anion with alkyl bromides.
The dianion of acenaphthylene is easily formed in spite
of its small size.[4][5] It is known from the 13C-NMR spectra
of the dianion and from semiempirical calculations that the
highest charge density is located at C-5.[6][7][8] The calcu-
lations show that the highest HOMO coefficient is also lo-
cated on this carbon atom. Therefore, electrophiles are ex-
pected to react at position 5 of the acenaphthylene dianion.
From experiments with proton donors it is known that the
first equivalent of proton reacts selectively at position 5,
resulting in the 5-hydroacenaphthylene anion (Scheme 2).[1]
The next equivalent of protons is added at position 1, thus
resulting in 1,5-dihydroacenaphthylene.[2][9]
Results
The 5-hydroacenaphthylene anion was prepared starting
from acenaphthylene, which was converted into its dianion
Eur. J. Org. Chem. 1998, 1907Ϫ1914
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M. E. Van Loo, J. Lugtenburg, J. Cornelisse
FULL PAPER
using 2.2 equivalents of sodium in anhydrous THF and selective: alkylation occurred at position 1 as well as at posi-
ultrasonic vibration. Within 3Ϫ5 hours the colour of the tion 2a.
solution turned deep green, indicating that the dianion had
been formed. The reaction mixture was cooled to Ϫ70°C
and exactly one equivalent of anhydrous methanol was ad-
1H- and 13C-NMR Spectroscopy
1
The H- and 13C-NMR spectra of the products were as-
ded. The reaction mixture was stirred for a further 15 min- signed using H-H and C-H inverse COSY techniques. The
utes at room temperature. After cooling the solution to 1H-NMR spectrum of 1-allylacenaphthene (1a) (Figure 1)
Ϫ70°C one equivalent of allyl bromide was added to the consists of signals of 6 aromatic, 3 olefinic, 3 benzylic, and
hydroanion and the mixture was stirred at room tempera- 2 allylic protons.
ture during a further 30 minutes. After extraction with light
The aromatic part of the spectrum consists of two sepa-
petroleum ether and the usual work-up, 1-allylacenaph- rated ABC patterns. Next to the expected ortho and meta
thene (1a) was obtained as the major product. 1-Allyl-1,5- couplings 3-H and 5-H show additional small couplings,
dihydroacenaphthylene, the initially formed product, is very which could be ascribed to coupling with 2-H and 2Ј-H. A
unstable and rearranges easily to the acenaphthene deriva- similar coupling can be observed between 1-H and 6-H and
tive Ϫ not only under slightly acidic conditions, but also on between 1-H and 8-H. These couplings were confirmed by
a silica gel column or at elevated temperatures Ϫ and could long-range H-H COSY and decoupling experiments. The
not be isolated. GC-MS analyses of the crude product non-aromatic part shows an ABCMNXYZ pattern. The
showed the presence of acenaphthene, a mono- and a dial- two protons at C-2, with a large negative geminal coupling
lylated acenaphthene in the ratio of 1:3:1 (Table 1). These constant, have different coupling constants with 1-H, the
products could not be separated by means of chromatogra- cis coupling being the larger one. 1-H also couples with the
phy on a silica gel column. Kugelrohr distillation of the distinguishable protons at C-9. This difference between 9-
product mixture gave rise to polymerisation reactions. H and 9Ј-H is induced by the chirality at C-1, but the as-
Therefore, preparative gas chromatography was used to sep- signment of the individual protons on the basis of a molec-
arate the products and 50Ϫ100 mg of pure products were ular model and these NMR results is not possible. Selective
isolated for NMR measurements.
substitution of 9-H or 9Ј-H with deuterium is necessary to
By means of NMR techniques the alkylation products discriminate between both protons.[11][12] The ddddЈs from
were identified as 1-allylacenaphthene (1a) and 1,1-dial- 9-H and 9Ј-H are due to the coupling with 10-H and allylic
lylacenaphthene (1b) (Scheme 3).
coupling with 11-H and 11Ј-H. 11-H and 11Ј-H have coup-
The same procedure was used with 3,3-dimethylallyl bro- ling constants of 16.8 and 10.3 Hz with 10-H, and can be
mide as electrophile. 1-(3-Methyl-2-butenyl)acenaphthene assigned as (E) and (Z) respectively, because J(Z) < J(E).
(2a) and 1,1-bis(3-methyl-2-butenyl)acenaphthene (2b) were For the determination of the coupling constants we used
formed in a 3:1 ratio (Table 1). The products could easily the simulation program PERCH. The 13C-NMR spectrum
be separated by preparative GC and were characterized by was consistent with this structure.
NMR.
The spectra of the other 1-substituted acenaphthenes
Use of propargyl bromide gave similar results. The prod- were similar to the spectrum described above and all ex-
ucts, 1-propargylacenaphthene (3a) and 1,1-dipropargyl- pected couplings were found. In the case of 1-(3-methyl-2-
acenaphthene (3b), were separated by preparative GC and butenyl)acenaphthene (2a) the methyl groups showed allylic
could be isolated in a 3:1 ratio (Table 1).
couplings with the olefinic proton. The aliphatic part in the
spectrum of 1-(cyclopropylmethyl)acenaphthene (4) was
too complex to obtain all the coupling constants.
In the 1,1-disubstituted acenaphthenes the molecules
have a plane of symmetry. Therefore, both 2-H’s are iden-
tical. The same might be expected for 9-H and 9Ј-H, but
although the signals moved towards each other and the
coupling between them decreased, they were still separated.
This might be the result of steric interactions.
In 1,1-dipropargylacenaphthene a remarkable shift of the
8-H signal towards lower field is observed. This is probably
caused by the influence of the π-electrons of propargyl sub-
stituents at C-1. A second deviation from the other spectra
are the coupling constants between 6-H and both 7-H and
8-H. J6,8 increased to 7.0 Hz, J6,7 however decreased to
2.0 Hz.
With (bromomethyl)cyclopropane only the monoalkyl-
ated product was formed next to acenaphthene in a 1:2 ratio
(Table 1). Separation was performed by crystallisation of
the acenaphthene followed by Kugelrohr distillation of the
resulting oil to yield 1-(cyclopropylmethyl)acenaphthene
(4).
Table 1: Results of the reaction of the 5-hydroacenaphthylene anion
with electrophiles[a]
Electrophile
overall yield
ratio A/1-R-A/1,1-R2-A
Allyl bromide
96%
93%
95%
96%
1:3:1
1:3:1
1:3:1
2:1:0
3,3-Dimethylallyl bromide
Propargyl bromide
(Bromomethyl)cyclopropane
[a]A ϭ acenaphthene, R ϭ substituent.
The spectrum of 1-benzylacenaphthene (5a) and 2a-
benzyl-2a,5-dihydroacenaphthylene (5b) was resolved using
The results of these reactions prompted us to also use the H-H and C-H inverse COSY spectrum. The olefinic
benzyl bromide (see Discussion). Preliminary results part of the spectrum confirmed the structure of 2a-benzyl-
showed that the reaction with benzyl bromide was less 2a,5-dihydroacenaphthylene (5b). Because the products
1908
Eur. J. Org. Chem. 1998, 1907Ϫ1914

Reactivity of the 5-Hydroacenaphthylene Anion towards Electrophiles
Scheme 3. Reductive alkylation of acenaphthylene with alkyl bromides
FULL PAPER
Figure 1. 1-Allylacenaphthene
pected to react in the same way with the 5-hydroacenaph-
thylene anion, thus giving 1-allylacenaphthene. In our
experiments three products were formed: acenaphthene and
1,1-diallylacenaphthene (1b) were isolated next to the ex-
pected 1-allylacenaphthene (1a). Obviously, the proton at
position 1 of 1-allyl-1,5-dihydroacenaphthylene can easily
be abstracted to give a 1-substituted 5-hydroanion. This hy-
droanion can react with a second allyl bromide to give the
doubly substituted product. Two bases are present in the
reaction mixture: one equivalent of methoxide, generated by
the reaction of methanol with the dianion, and unreacted 5-
hydroacenaphthylene anion. If the latter acts as a base this
results in the formation of acenaphthene. Addition of two
equivalents of allyl bromide gave approximately the same
product ratio as in the experiment using only one equivalent
of allyl bromide. If methoxide would be the most important
base, a substantially larger amount of 1,1-diallylacenaph-
thene (1b) should be formed and less acenaphthene. Be-
cause the product ratio did not change, it may be concluded
that the hydroanion is the strongest base in this process
could not be separated, it was impossible to assign the 13C-
NMR spectrum completely.
Discussion
The 5-hydroacenaphthylene anion can easily be prepared
by addition of one equivalent of methanol to the dianion.
This hydroanion reacts with methyl iodide at position 1 to
give 1-methyl-1,5-dihydroacenaphthylene as the sole prod-
uct. This unstable product rearranges under slightly acidic
conditions to 1-methylacenaphthene. Allyl bromide is ex-
Eur. J. Org. Chem. 1998, 1907Ϫ1914
1909

M. E. Van Loo, J. Lugtenburg, J. Cornelisse
FULL PAPER
(Scheme 4). Addition of potassium tert-butoxide, after ad- ical will react at C-1 and at C-3, differently substituted in
dition of two equivalents of allyl bromide, did not result in 3,3-dimethylallyl bromide. However, occurrence of the SET
more dialkylated product. Similarly, when a solution of 1,5- mechanism is unlikely because of the absence of products
dihydroacenaphthylene was first treated with one equivalent with methyl groups at C-9 (SN2Ј product). The reaction
of sodium methoxide and subsequently with excess electro- products indicate that the SN2 mechanism must be the most
philic reagent, no substitution product could be detected. important one.
This also confirms the assumption that the 5-hydroace-
A similar conclusion can be drawn from the experiment
naphthylene anion is a stronger base than methoxide. Ap- with (bromomethyl)cyclopropane: if electron transfer were
parently the 1-propynyl anion is a stronger base than 5- part of the substitution, the cyclopropylmethyl radical
hydroacenaphthylene anion, because otherwise the reaction would be opened immediately to a butenyl radical (Scheme
with propargyl bromide would yield much more acenaph- 6). 1-(3-Butenyl)acenaphthene (6) was, however, not ob-
thene, since the acetylenic moiety would be a proton donor served. The yield of 1-(cyclopropylmethyl)acenaphthene (4)
for the 5-hydroacenaphthylene anion. The acidity of 1,5- was relatively low (30%) in comparison with methyl iodide.
dihydroacenaphthylene is expected to be in the vicinity of This may be explained by the lower reactivity of (bromo-
that of indene (pKa ϭ 20). The results of the reaction are methyl)cyclopropane compared to methyl iodide.
in agreement with this estimated pKa compared with the
acidity of methanol (pKa ϭ 15.2) and acetylene (pKa ϭ 25).
The reactivity at position 1 can be rationalised by the
distribution of charge and the HOMO coefficients in the 5-
In the reaction with methyl iodide no doubly alkylated hydroacenaphthylene anion (Figure 2). The calculations
product is formed. A possible explanation is that methyl were performed with MOPAC93, using the PM3 method.
iodide is more reactive towards the hydroanion, thus con- The calculated charge distribution can be compared to the
verting all the hydroanion immediately to the neutral com- one inferred from the 13C-NMR spectrum of the 5-hydro-
pound and quenching further reaction. The higher reactiv- acenaphthylene anion. From the value of the chemical shift
ity of methyl iodide is in agreement with the influence of the highest charge is expected at carbon atom 1. To obtain
the leaving group (iodide vs. bromide) and the substituent the charge distribution, electrostatic potential calculation
(methyl vs. allyl).[13][14]
was used. This calculation, however, predicts a very high
Scheme 4. Equilibrium in the reaction of the 5-hydroacenaphthylene anion with allyl bromide
Allyl bromide can react by three mechanisms with nucle- charge at C-4, which disagrees with the 13C-NMR spec-
ophiles: SN2, SN2Ј, or single electron transfer (SET). From trum. Calculation of the total atomic charges did not lead
the results of the reaction of the hydroanion with 3,3-di- to better agreement. Because reaction with alkyl halides
methylallyl bromide it can be concluded that the SN2Ј normally occurs at carbon atom 1, we may assume that the
mechanism does not play a significant role (Scheme 5). In highest charge is at C-1 indeed. The combination of highest
the SET mechanism one electron is transferred from the charge and high HOMO coefficient is the reason that the
hydroanion to the allyl bromide. The latter radical anion reaction with most electrophiles takes preferably place at
splits into an allyl radical and a bromide ion. The allyl rad- position 1. However, the highest HOMO coefficient is
Scheme 5. SN2 and SN2Ј mechanism of the reaction of 3,3-dimethylallyl bromide with the 5-hydroacenaphthylene anion
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Eur. J. Org. Chem. 1998, 1907Ϫ1914

Reactivity of the 5-Hydroacenaphthylene Anion towards Electrophiles
FULL PAPER
Scheme 6. Possible pathways for the reaction of (bromomethyl)cyclopropane with 5-hydroacenaphthylene anion
found at C-2a. It is known that soft electrophiles such as thermodynamic stability of the products but the hardness
benzyl bromide will react at the position with the highest or softness of the electrophiles and the carbon atoms of
HOMO coefficient.
the anion are responsible for the observed regioselectivity.
Reactions with other soft electrophiles are still under inves-
tigation.
Figure 2. Distribution of charge and HOMO coefficients in 5-hy-
droacenaphthylene anion
Conclusions
Reaction of the 5-hydroacenaphthylene anion with un-
saturated alkyl bromides provides an easy route to intro-
duce functional groups at position 1. In the case of allyl
bromide, 3,3-dimethylallyl bromide and propargyl bromide
a considerable amount of 1,1-dialkylated product could be
isolated. This is the first route to obtain these disubstituted
products selectively. The mechanism was proved to be SN2
by reaction with dimethylallyl bromide and (bromometh-
yl)cyclopropane. Reaction with benzyl bromide is less selec-
tive because the soft electrophile reacts also at the position
with the highest HOMO coefficient and a unique 2a-benzyl-
ated acenaphthylene is generated.
The authors wish to thank Joke van Dijk-Knepper for the prep-
arative gas chromatography.
Experimental Section
Preliminary results of the reaction of benzyl bromide
with 5-hydroacenaphthylene anion indicated that substi-
tution occurred at position 1 as well as at 2a, in a ratio of
1:1 (Scheme 7). Similar results have been reported in the
literature[15][16] for the reactions of the phenalenyl and
hydropyrenyl anions with soft electrophiles such as benzyl
iodide and propyl iodide. Here also the electrophiles reacted
at the position with the highest HOMO, creating a quater-
nary carbon atom. Reactions of the 5-hydroacenaphthylene
anion with electrophiles are subject to kinetic control, i.e.
General: Acenaphthylene (75%) was obtained from Aldrich and
purified by treatment with DDQ and filtration through silica gel.
Allyl bromide, 3,3-dimethylallyl bromide, propargyl bromide,
(bromomethyl)cyclopropane, and benzyl bromide were obtained
from Acros and used without further purification. Methanol was
purchased from Acros, distilled from sodium and stored over mo-
˚
lecular sieves (3 A, 8Ϫ12 mesh). Tetrahydrofuran was purchased
from Acros and distilled from sodium and benzophenone immedi-
ately before use. The 300-MHz 1H-NMR spectra and 75-MHz 13C-
NMR spectra were recorded with a Bruker WM-300 spectrometer.
The 600-MHz 1H-NMR spectrum of 1-propargylacenaphthene was
they are irreversible. We therefore assume that not the recorded with a Bruker AM-600 spectrometer. All chemical shift
Scheme 7. Reaction of the 5-hydroacenaphthylene anion with benzyl bromide
Eur. J. Org. Chem. 1998, 1907Ϫ1914
1911

M. E. Van Loo, J. Lugtenburg, J. Cornelisse
FULL PAPER
data (δ) are given in ppm relative to tetramethylsilane (TMS); the J1,9Ј ϭ 8.4, J1,8 ϭ 1.6, J1,6 ϭ 0.7 1 H, 1-H), 3.54 (dddd, J2,2Ј
coupling constants (J) are given in Hz. Coupling constants in the Ϫ17.5, J1,2 ϭ 8.8, J2.5 ϭ 1.2, J2,3 ϭ 0.9, 1 H, 2-H), 3.10 (dddd,
range 1.2Ϫ0.5 Hz were determined by simulation with the program J2,2Ј ϭ Ϫ17.5, J1,2Ј ϭ 4.2, J2Ј,5 ϭ 1.2, J2Ј,3 ϭ 1.0, 1 H, 2Ј-H), 2.67
ϭ
PERCH[17] and give an indication of the real value with a deviation (dddd, J9,9Ј ϭ Ϫ14.6, J1,9 ϭ 4.7, J9,10 ϭ 6.5 J9,11 ϭ 1.3, J9,11Ј
ϭ
of ±0.2 Hz. Identification of the products was performed using 1H-
1.4, 1 H, 9-H), 2.54 (dddd, J9,9Ј ϭ Ϫ14.6, J1,9ЈЈ ϭ 8.4, J9Ј,10 ϭ 7.1
1
1H and H-13C correlated 2D NMR spectra. Preparative GC was J9Ј,11 ϭ 1.3, J9Ј,11Ј ϭ 1.4, 1 H, 9Ј-H). Ϫ 13C NMR (CDCl3): δ ϭ
performed with an ATI Unicam 610 series gas chromatograph 148.8 (C-2a or C-8a), 144.5 (C-2a or C-8a), 138.7 (C-8b), 136.5 (C-
equipped with an SE 15% 3-m column with the following tempera-
10), 131.5 (C-5a), 127.8 (C-4 or C-7), 127.7 (C-4 or C-7), 122.7 (C-
ture profile: 10 min 100°C, 10°C/min to 160°C, 15 min 160°C. 5 or C-6), 122.3 (C-5 or C-6), 119.2 (C-3 or C-8), 118.9 (C-3 or C-
Mass spectra were recorded with a Finnigan MAT 900 mass spec- 8), 116.5 (C-11), 42.6 (C-1), 40.6 (C-9), 36.9 (C-2). Ϫ C15H14: calcd.
trometer equipped with a direct insertion probe (EI-MS, 70 eV) or
194.1096; found 194.1087. Ϫ MS; m/z (%): 194 (17), 165 (6), 153
with a Finnigan MAT ITD 700 (EI, 70 eV) coupled to a Packard (100), 127 (1), 89 (2).
438A gas chromatograph equipped with a Chrompack 25-m fused
silica column (CP-Sil-5CB; 0.25 mm i.d.) (GC-MS).
General Procedure: Into a dry 250-ml three-necked round-bot-
tomed flask 125 ml of THF was distilled under argon. 0.761 g (5
mmol) of acenaphthylene was added, together with 0.3 g (13 mmol)
of freshly cut sodium. Directly after the addition, the flask was
evacuated and sonicated for a period of 40 s. Argon was admitted
and sonication restarted. The solution immediately turned dark
brown, indicating that the radical anion had been formed. After 5
h of sonication, during which the temperature was kept at 0°C, a
deep green solution was obtained. The flask was then cooled in an
ethanol/liquid nitrogen bath to Ϫ70°C and 0.146 ml (5 mmol) of
methanol was added. The colour of the mixture turned red. The
mixture was allowed to warm to room temperature and stirred for
a further 10 min. The mixture was cooled again to Ϫ70°C and 5
mmol of alkyl bromide was added. Stirring was continued at room
temperature for 30 min after which period the reaction was
quenched with water. Addition of light petroleum ether (boiling
range 40Ϫ60°C), extraction with water, washing with brine, drying
with MgSO4 and evaporation of the solvents in vacuo resulted in
the isolation of a viscous oil. With a small amount of HCl in ace-
tone, all the products were converted into acenaphthene derivatives.
A fraction of each product mixture was separated by means of
preparative GC in order to obtain pure material for NMR spec-
troscopy.
1,1-Diallylacenaphthene (1b): 1H NMR (CDCl3, TMS): δ ϭ 7.63
(dd, J6,7 ϭ 8.1, J6.8 < 0.7, 1 H, 6-H), 7.61 (dddd, J4,5 ϭ 8.5, J2.5 ϭ
1.0, J2Ј,5 ϭ 0.8, J3,5 < 0.7, 1 H, 5-H), 7.48 (dd, J6,7 ϭ 8.1, J7,8
7.0, 1 H, 7-H), 7.45 (dd, J3,4 ϭ 6.9, J4,5 ϭ 8.5, 1 H, 4-H), 7.24 (dd,
J7,8 ϭ 7.0, J6.8 < 0.7, 1 H, 8-H), 7.22 (dddd, J3,4 ϭ 6.9, J2,3 ϭ 1.4,
ϭ
J2Ј,3 ϭ 0.9, J3,5 < 0.7, 1 H, 3-H), 5.57 (dddd, J10,11 ϭ 16.6, J10,11Ј
ϭ
10.3, J9,10 ϭ 6.4, J9Ј,10 ϭ 8.1, 2 H, 10-H), 5.04 (dddd, J11,11Ј
ϭ
Ϫ3.0, J10,11 ϭ 16.6, J9,11 ϭ J9Ј,11 ϭ 1.2, 2 H, 11-H), 4.94 (dddd,
J11,11Ј ϭ Ϫ3.0, J10,11Ј ϭ 10.3, J9,11Ј ϭ J9Ј,11Ј ϭ 1.3, 2 H, 11Ј-H),
3.27 (dd, J2.5 ϭ 1.0, J2,3 ϭ 1.4, 1 H, 2-H), 3.26 (dd, J2Ј,5 ϭ 0.8,
J2Ј,3 ϭ 0.9, 1 H, 2Ј-H), 2.55 (ddd, J9,9Ј ϭ Ϫ1.8, J9,10 ϭ 6.4, J9,11 ϭ
1.2, J9,11Ј ϭ 1.3, 2 H, 9-H), 2.53 (ddd, J9,9Ј ϭ Ϫ1.8, J9Ј,10 ϭ 8.1,
J9Ј,11 ϭ 1.2, J9Ј,11Ј ϭ 1.3, 2 H, 9Ј-H). Ϫ 13C NMR (CDCl3): δ ϭ
150.7 (C-2a or C-8a), 143.4 (C-2a or C-8a), 138.4 (C-8b), 134.6 (C-
10), 131.2 (C-5a), 127.9 (C-4 or C-7), 127.7 (C-4 or C-7), 123.0 (C-
5 or C-6), 122.3 (C-5 or C-6), 119.1 (C-3 or C-8), 118.4 (C-3 or C-
8), 117.7 (2 C-11), 50.5 (C-1), 45.4 (C-9), 41.4 (C-2). Ϫ C18H18:
calcd. 234.1408; found 234.1389. Ϫ MS; m/z (%): 234 (15), 193
(100), 152 (17).
Reaction of the 5-Hydroacenaphthylene Anion with Allyl Bromide:
To the 5-hydroacenaphthylene anion, prepared according to the
general procedure, 0.866 ml (5 mmol) of allyl bromide was added.
Column chromatography on silica gel using light petroleum ether
as eluent gave a mixture of mono- and dialkylated products. The
mass recovery was 96%.
Reaction of the 5-Hydroacenaphthylene Anion with 3,3-Dimethyl-
allyl Bromide: To the 5-hydroacenaphthylene anion, prepared ac-
cording to the general procedure, 0.576 ml (5 mmol) of 3,3-di-
methylallyl bromide was added. Column chromatography on silica
gel using light petroleum ether as eluent gave a mixture of mono-
and dialkylated product. The mass recovery was 93%.
1-(3-Methyl-2-butenyl)acenaphthene (2a): 1H NMR (CDCl3,
TMS): δ ϭ 7.61 (ddd, J6,7 ϭ 8.2, J1,6 ϭ 0.6, J6.8 ϭ 1.0, 1 H, 6-H),
7.60 (dddd, J4,5 ϭ 8.2, J2.5 ϭ J2Ј,5 ϭ 1.1, J3,5 ϭ 1.0, 1 H, 5-H),
7.45 (dd, J6,7 ϭ 8.2, J7,8 ϭ 6.9, 1 H, 7-H), 7.44 (dd, J3,4 ϭ 6.9,
J4,5 ϭ 8.2, 1 H, 4-H), 7.29 (ddd, J7,8 ϭ 6.9, J1,8 ϭ 0.8, J6.8 ϭ 1.0,
1-Allylacenaphthene (1a): 1H NMR (CDCl3, TMS): δ ϭ 7.61
(ddd, J6,7 ϭ 8.2, J1,6 ϭ 0.7, J6.8 ϭ 1.1, 1 H, 6-H), 7.60 (dddd, J4,5 ϭ 1 H, 8-H), 7.26 (dddd, J3,4 ϭ 6.9, J2,3 ϭ J2Ј,3 ϭ 1.1, J3,5 ϭ 1.0, 1
8.4, J2.5 ϭ J2Ј,5 ϭ 1.2, J3,5 ϭ 0.7, 1 H, 5-H), 7.46 (dd, J6,7 ϭ 8.2, H, 3-H), 5.28 (ddqq, J10,Me ϭ 1.4, J10,MeЈ ϭ 1.5, J9,10 ϭ 7.1, J9Ј,10 ϭ
J7,8 ϭ 6.9, 1 H, 7-H), 7.45 (dd, J3,4 ϭ 6.7, J4,5 ϭ 8.4, 1 H, 4-H),
7.30 (ddd, J7,8 ϭ 6.9, J1,8 ϭ 1.6, J6.8 ϭ 1.1, 1 H, 8-H), 7.26 (dddd, J1,9Ј ϭ 8.4, J1,8 ϭ 0.8, J1,6 ϭ 0.6, 1 H, 1-H), 3.54 (dddd, J2,2Ј
3,4 ϭ 6.7, J2,3 ϭ 0.9, J2Ј,3 ϭ 1.0, J3,5 ϭ 0.7, 1 H, 3-H), 5.89 (dddd, Ϫ17.4, J1,2 ϭ 8.0, J2.5 ϭ 1.0, J2,3 ϭ 1.1, 1 H, 2-H), 3.04 (dddd,
J10,11 ϭ 16.8, J10,11Ј ϭ 10.3, J9,10 ϭ 6.5, J9Ј,10 ϭ 7.1, 1 H, 10-H), J2,2Ј ϭ Ϫ17.4, J1,2Ј ϭ 3.6, J2Ј,5 ϭ J2Ј,3 ϭ 1.1, 1 H, 2Ј-H), 2.59
5.13 (dddd, J11,11Ј ϭ Ϫ2.2, J10,11 ϭ 16.8, J9,11 ϭ J9Ј,11 ϭ 1.3, 1 H, (dddqq, J9,9Ј ϭ Ϫ14.1, J9,10 ϭ 7.1, J1,9 ϭ 6.1, J9,Me ϭ 0.7, J9,MeЈ
11-H), 5.07 (dddd, J11,11Ј ϭ Ϫ2.2, J10,11Ј ϭ 10.3, J9,11Ј ϭ J9Ј,11Ј 0.9, 1 H, 9-H), 2.36 (dddqq, J9,9Ј ϭ Ϫ14.1, J9Ј,10 ϭ 7.1 J1,9Ј ϭ 8.4,
1.4, 1 H, 11Ј-H), 3.78 (dddddd, J1,2 ϭ 8.8, J1,2Ј ϭ 4.2, J1,9 ϭ 4.7, J9Ј,Me ϭ 0.7, J9Ј,MeЈ ϭ 0.9, 1 H, 9Ј-H), 1.73 (ddd, J10,Me ϭ 1.4,
7.1, 1 H, 10-H), 3.71 (dddddd, J1,2 ϭ 8.0, J1,2Ј ϭ 3.6, J1,9 ϭ 6.1,
ϭ
J
ϭ
ϭ
1912
Eur. J. Org. Chem. 1998, 1907Ϫ1914

Reactivity of the 5-Hydroacenaphthylene Anion towards Electrophiles
FULL PAPER
J9,Me ϭ 0.7, J9Ј,Me ϭ 0.7, 3 H, Me), 1.61 (ddd, J10,MeЈ ϭ 1.5,
J9,MeЈ ϭ 0.9, J9Ј,MeЈ ϭ 0.9, 3 H, MeЈ). Ϫ 13C NMR (CDCl3): δ ϭ
148.8 (C-2a or C-8a), 144.5 (C-2a or C-8a), 138.7 (C-8b) 131.5 (C-
5a), 128.6 (C-4 and C-7), 123.4 (C-10), 123.3 (C-5 or C-6), 123.0
(C-5 or C-6), 119.9 (C-3 or C-8), 119.6 (C-3 or C-8), 44.5 (C-Me,
2 ϫ), 41.2 (C-1), 38.9 (C-9), 36.5 (C-2). Ϫ C17H18: calcd. 222.1408;
found 222.1476. Ϫ MS; m/z (%): 222 (27), 184 (8), 153 (100), 127
(5).
(C-5 or C-6), 122.4 (C-5 or C-6), 119.3 (C-3 or C-8), 119.1 (C-3 or
C-8), 69.2 (C-11), 42.2 (C-1), 37.4 (C-2), 25.4 (C-9). Ϫ C15H12:
calcd. 192.0939; found 192.0933. Ϫ MS; m/z (%): 192 (18), 153
(100), 126 (2).
1,1-Dipropargylacenaphthene (3b): 1H NMR (CDCl3, TMS): δ ϭ
7.69 (ddd, J6,7 ϭ 2.0, J6.8 ϭ 7.0, 1 H, 6-H), 7.65 (ddt, J4,5 ϭ 8.5,
J2.5, J3,5, 1 H, 5-H), 7.51 (dd, J6,7 ϭ 2.0, J7,8 ϭ 7.0, 1 H, 7-H), 7.50
(ddd, J7,8 ϭ 7.0, J6.8 ϭ 7.0, 1 H, 8-H), 7.49 (dd, J3,4 ϭ 6.9, J4,5
ϭ
8.5, 1 H, 4-H), 7.30 (ddt, J3,4 ϭ 6.9, J2,3, J3,5, 1 H, 3-H), 3.46 (s, 2
H, 2-H), 2.83 (dd, J9,9Ј ϭ Ϫ16.7, J9,11 ϭ 2.6, 2 H, 9-H), 2.75 (dd,
1,1-Bis(3-methyl-2-butenyl)acenaphthene (2b): 1H NMR (CDCl3,
TMS): δ ϭ 7.61 (dd, J6,7 ϭ 8.2, J6.8 ϭ 0.6, 1 H, 6-H), 7.60 (ddt, J9,9Ј ϭ Ϫ16.7, J9Ј,11 ϭ 2.6, 2 H, 9Ј-H), 1.98 (dd, J9,11 ϭ J9Ј,11
ϭ
J4,5 ϭ 8.0, J2.5 ϭ 0.9, J3,5 ϭ 0.5, 1 H, 5-H), 7.46 (dd, J6,7 ϭ 8.2, 2.6, 2 H, 11-H). Ϫ 13C NMR (CDCl3): δ ϭ 128.0 (C-4 or C-7),
J7,8 ϭ 7.0, 1 H, 7-H), 7.44 (dd, J3,4 ϭ 6.9, J4,5 ϭ 8.0, 1 H, 4-H), 127.7 (C-4 or C-7), 124.0 (C-5 or C-6), 122.7 (C-5 or C-6), 119.5
7.23 (dd, J7,8 ϭ 7.0, J6.8 ϭ 0.6, 1 H, 8-H), 7.19 (ddt, J3,4 ϭ 6.9,
J2,3 ϭ 1.2, J3,5 ϭ 0.5, 1 H, 3-H), 5.01 (ddqq, J10,Me ϭ J10,MeЈ
1.4, J9,10 ϭ 7.9, J9Ј,10 ϭ 6.7, 2 H, 10-H), 3.18 (dd, J2,3 ϭ 1.2, J2,5 ϭ
(C-3 or C-8), 118.9 (C-3 or C-8), 70.4 (C-11, C11Ј), 43.4 (C-2), 31.5
(C-9), quaternary carbon atom signals not observed. Ϫ C18H14:
calcd. 230.1095; found: 230.1083. Ϫ MS; m/z (%): 230 (24), 191
ϭ
0.9, 2 H, 2-H), 2.50 (ddqq, J9,9Ј ϭ Ϫ14.6, J9,10 ϭ 7.9, J9,Me ϭ 0.7, (100), 152 (24).
J9,MeЈ ϭ 0.9, 2 H, 9-H), 2.41 (ddqq, J9,9Ј ϭ Ϫ14.6, J9Ј,10 ϭ 6.7,
Reaction of the 5-Hydroacenaphthylene Anion with (Bromometh-
J9Ј,Me ϭ 1.2, J9Ј,MeЈ ϭ 1.5, 2 H, 9Ј-H), 1.59 (ddd, J10,Me ϭ 1.4,
J9,Me ϭ 0.7, J9Ј,Me ϭ 1.2, 6 H, Me), 1.54 (ddd, J10,MeЈ ϭ 1.4,
J9,MeЈ ϭ 0.9, J9Ј,MeЈ ϭ 1.5, 6 H, MeЈ).
yl)cyclopropane: To the 5-hydroacenaphthylene anion, prepared ac-
cording to the general procedure using 0.457 g (3 mmol) of ace-
naphthylene and 0.121 ml (3 mmol) of methanol, 0.357 ml (3
mmol) of (bromomethyl)cyclopropane was added. The crude prod-
uct was filtered through silica gel with light petroleum ether as
Reaction of the 5-Hydroacenaphthylene Anion with Propargyl
Bromide: To the 5-hydroacenaphthylene anion, prepared according
to the general procedure, 0.446 ml (5 mmol) of propargyl bromide eluent. The product mixture consisted of acenaphthene and 1-
were added. Column chromatography on silica gel using light (cyclopropylmethyl)acenaphthene in a 2:1 ratio. The mass recovery
petroleum ether as eluent gave a mixture of mono- and dialkylated was 96%. The major part of the acenaphthene could be removed
product. The mass recovery was 95%.
1-Propargylacenaphthene (3a): 1H NMR (CDCl3, TMS): δ ϭ
7.64 (ddd, J6,7 ϭ 8.1, J1,6 ϭ 0.7, J6.8 ϭ 0.7, 1 H, 6-H), 7.61 (dddd,
by crystallisation from light petroleum ether. Kugelrohr distillation
of the oil gave 187 mg (0.9 mmol, 30%) of > 90% pure 1-(cyclopro-
pylmethyl)acenaphthene in the second fraction.
1-(Cyclopropylmethyl)acenaphthene (4): 1H NMR (CDCl3,
TMS): δ ϭ 7.59 (d, J6,7 ϭ 8.2, 1 H, 6-H), 7.58 (d, J4,5 ϭ 8.2, 1 H,
J4,5 ϭ 8.2, J2.5 ϭ J2Ј,5 ϭ 1.1, J3,5 ϭ 0.8, 1 H, 5-H), 7.47 (dd, J6,7 ϭ
8.1, J7,8 ϭ 6.9, 1 H, 7-H), 7.46 (dd, J3,4 ϭ 6.8, J4,5 ϭ 8.2, 1 H, 4-
H), 7.41 (ddd, J7,8 ϭ 6.9, J1,8 ϭ 1.2, J6.8 ϭ 0.7, 1 H, 8-H), 7.28 5-H), 7.44 (dd, J6,7 ϭ 8.2, J7,8 ϭ 6.8, 1 H, 7-H), 7.43 (dd, J4,5
ϭ
(dddd, J3,4 ϭ 6.8, J2,3 ϭ J2Ј,3 ϭ 1.1, J3,5 ϭ 0.8, 1 H, 3-H), 3.90 8.2, J3,4 ϭ 6.8, 1 H, 4-H), 7.26 (d, J7,8 ϭ 6.8, 1 H, 8-H), 7.25 (d,
(dddddd, J1,2 ϭ 8.1, J1,2Ј ϭ 3.5, J9Ј,1 ϭ 8.0, J9,1 ϭ 6.2, J1,8 ϭ 1.2,
J1,6 ϭ 0.7, 1 H, 1-H), 3.67 (dddd, J2,2Ј ϭ Ϫ17.5, J1,2 ϭ 8.1, J2.5
J3,4 ϭ 6.8, 1 H, 3-H), 3.76 (m, 1 H, 1-H), 3.60 (dd, J2,2Ј ϭ Ϫ17.2,
J1,2 ϭ 8.0, 1 H, 2-H), 3.17 (d, J2,2Ј ϭ Ϫ17.2, J1,2Ј ϭ 3.5, 1 H, 2Ј-
ϭ
J2,3 ϭ 1.1, 1 H, 2-H), 3.22 (dddd, J2,2Ј ϭ Ϫ17.5, J1,2Ј ϭ 3.5, J2Ј,5 ϭ H), 1.72 (ddd, J9,9Ј ϭ Ϫ13.5, J9,10 ϭ 7.2, J1,9 ϭ 5.5, 1 H, 9-H),
J2Ј,3 ϭ 1.1, 1 H, 2Ј-H), 2.72 (ddd, J9,9Ј ϭ Ϫ16.7, J9,1 ϭ 6.2, J9,11 ϭ 1.63 (ddd, J9,9Ј ϭ Ϫ13.5, J9Ј,10 ϭ J1,9Ј ϭ 6.33, 1 H, 9Ј-H), 0.89 (m,
2.6, 1 H, 9-H), 2.55 (ddd, J9,9Ј ϭ Ϫ16.7, J9Ј,1 ϭ 8.0, J9Ј,11 ϭ 2.7, 1 1 H, 10-H), 0.51 (ddd, 2 H, 11-H), 0.19 (ddd, 2 H, 12-H). Ϫ 13C
H, 9-H), 1.98 (dd, J9,11 ϭ 2.6, J9Ј,11 ϭ 2.7, 1 H, 11-H). Ϫ 13C NMR NMR (CDCl3): δ ϭ 149.5 (C-2a or C-8a), 144.8 (C-8a or C-2a),
(CDCl3): δ ϭ 148.8 (C-2a or C-8a), 143.7 (C-2a or C-8a), 138.7 138.6 (C-8b), 131.4 (C-5a), 127.8 (C-6 or C-5), 127.7 (C-5 or C-6),
(C-8b), 131.4 (C-5a), 127.9 (C-4 or C-7), 127.8 (C-4 or C-7), 123.3 122.5 (C-7 or C-4), 122.2 (C-4 or C-7), 119.1 (C-8 or C-3), 118.9
Eur. J. Org. Chem. 1998, 1907Ϫ1914
1913

M. E. Van Loo, J. Lugtenburg, J. Cornelisse
FULL PAPER
119.2 (C-8 and C-3), 44.63 (C-1), 42.7 (C-9), 37.3 (C-2); assignment
of the other CЈs was not possible.
2a-Benzyl-2a,5-dihydroacenaphthylene (5b): 1H NMR (CDCl3,
TMS): δ ϭ 7.39-7.28 (m, 5 H, H-arom.), 7.16 (m, 1 H, 7-H), 6.98-
6.94 (m, 2 H, 6-H, 8-H), 6.67 (d, J1,2 ϭ 5.5, 1 H, 1-H), 6.58 (d,
J1,2 ϭ 5.5, 1 H, 2-H), 6.18 (ddd, J3,4 ϭ 9.2, J3,5 ϭ 0.6, J3,5Ј ϭ 2.9,
1 H, 3-H), 6.13 (ddd, J3,4 ϭ 9.2, J4,5 ϭ 6.0, J4,5Ј ϭ 1.1, 1 H, 4-H),
3.10 (ddd, J5,5Ј ϭ Ϫ20.2, J3,5 ϭ 0.6, J4,5 ϭ 6.0, 1 H, 5-H), 3.01
(ddd, J5,5Ј ϭ Ϫ20.2, J3,5Ј ϭ 2.9, J4,5Ј ϭ 1.1, 1 H, 5Ј-H), 2.88 (d,
J9,9Ј ϭ Ϫ12.6, 1 H, 9-H), 2.61 (d, J9,9Ј ϭ Ϫ12.6, 1 H, 9Ј-H). Ϫ 13C
NMR (CDCl3): δ ϭ 142.5 (C-2), 130.0 (C-1), 129.1 (C-4), 128.4
(C-3), 46.2 (C-9), 30.4 (C-5); assignment of the other CЈs was not
possible.
(C-3 or C-8), 44.0 (C-1), 41.5 (C-9 or C-2), 37.5 (C-2 or C-9), 9.4
(C-10), 4.9 (C-11 or C-12), 4.8 (C-12 or C-11). Ϫ GC-MS showed
one product with mass 208. Ϫ MS; m/z (%): 208 (100), 166 (17),
153 (70).
Reaction of the 5-Hydroacenaphthylene Anion with Benzyl Bro-
mide: To the 5-hydroacenaphthylene anion, prepared according to
the general procedure using 0.457 g (3 mmol) of acenaphthylene
and 0.121 ml (3 mmol) of methanol, 0.357 ml (3 mmol) of benzyl
bromide was added. Column chromatography on silica gel using
light petroleum ether as eluent gave two fractions; the first con-
sisted of acenaphthene and benzyl bromide, the other contained
alkylated products. Kugelrohr distillation of the latter gave two
fractions and a residue. In the first (largest) fraction 1-benzylace-
naphthene and 2a-benzyl-2a,5-dihydroacenaphthylene were pre-
sent. The major product in the second fraction was 1-benzylace-
naphthene. The residue contained at least two dialkylated products.
[1]
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[10]
1-Benzylacenaphthene (5a): 1H NMR (CDCl3, TMS): δ ϭ 7.61
M. E. Van Loo, J. Lugtenburg, J. Cornelisse, Polycyclic Aro-
matic Compounds, submitted for publication.
(ddd, J6,7 ϭ 8.2, J1,6, J6.8, 1 H, 6-H), 7.60 (dddd, J4,5 ϭ 8.2, J2.5
,
[11]
J. Kobayashi, U. Nagai, Tetrahedron Lett. 1977, 1803Ϫ1804.
J2Ј,5, J3,5, 1 H, 5-H), 7.43 (dd, J6,7 ϭ 8.2, J7,8 ϭ 6.7, 1 H, 7-H),
[12]
T. Wabayashi, K. Watanabe, Tetrahedron Lett. 1977,
7.41 (dd, J3,4 ϭ 6.6, J4,5 ϭ 8.2, 1 H, 4-H), 7.23 (ddd, J7,8, J1,8, J6.8
1 H, 8-H), 7.20-7.12 (m, 5 H, H-arom), 7.05 (dddd, J3,4 ϭ 6.6, J2,3
,
,
4595Ϫ4598.
[13]
A. Streitwieser, Solvolytic displacement reactions, McGraw-Hill
Book Company, Inc., New York, 1st ed., 1962, p. 12Ϫ31.
J2Ј,3, J3,5, 1 H, 3-H), 4.01 (dddddd, J1,2 ϭ 8.1, J1,2Ј ϭ 2.3, J9Ј,1
ϭ
[14]
J. March, Advanced Organic Chemistry, J. Wiley and Sons Inc.,
8.9, J9,1 ϭ 7.5, J1,8, J1,6, 1 H, 1-H), 3.47 (dddd, J2,2Ј ϭ Ϫ17.0,
J1,2 ϭ 8.1, J2.5, J2,3, 1 H, 2-H), 3.19 (dd, J9,9Ј ϭ Ϫ14.0, J9,1 ϭ 7.5,
1 H, 9-H), 3.10 (dddd, J2,2Ј ϭ Ϫ17.0, J1,2Ј ϭ 2.3, J2Ј,5, J2Ј,3, 1 H,
New York, 4th ed., 1992, p. 339Ϫ357.
[15]
C. Schnieders, K. Müllen, W. Huber, Tetrahedron 1984,
1701Ϫ1711.
[16]
R. Brandsma, C. Tintel, J. Lugtenburg, J. Cornelisse, Synth.
2Ј-H), 2.89 (dd, J9,9Ј ϭ Ϫ17.0, J9Ј,1 ϭ 8.9, 1 H, 9-H). J1,6, J6.8, J7,8
,
Commun. 1985, 91Ϫ93.
J1,8, J6.8, J2.5, J2Ј,5, J3,5, J2,3, J2Ј,3, J3,5 were observed but not exactly
[17]
R. Laatikainen, M. Niemitz, U. Weber, J. Sundelin, T. Hassinen,
determined. Ϫ 13C NMR (CDCl3) : δ ϭ 122.8 (C-6), 122.3 (C-5),
J. Vepsaelaeinen, J. Magn. Reson. 1996, 120, 1Ϫ10.
[98137]
1914
Eur. J. Org. Chem. 1998, 1907Ϫ1914