Photolytic, thermal, addition, and cycloaddition reactions of 2-diazo-5,6- and -3,8-disubstituted acenaphthenones

Article abstract of DOI:10.1021/jo040175h

Preparation and varied thermal and photolytic reactions of 2-diazo-5,6-(disubstituted)acenaphthenones (11a-d) and 2-diazo-3,8- dimethoxyacenaphthenone (12) are reported. Alcohols react thermally and photolytically with 11a-c with losses of N₂ to yield 2-alkoxynaphthenones (24a,b and 47a,b) and acenaphthenones (25 and 48a,b). Aniline and diphenylamine are converted by 11a-c at 180°C to acenaph[1,2-6]indoles (29a,b and 53a,b). Thermolyses of 11a-c at ～450°C (0.15 mmHg) yield reduction products 25 and 48a,b, respectively. Wolff rearrangements to 1,8-naphthyleneketenes (15a-d) and/or their derivatives are not observed in the above experiments. Oxygen converts 11a-c thermally to acenaphthenequinones (19a-c) and/or 1,8-naphthalic anhydrides. Insertion, addition, substitution, and/or isomerization reactions occur upon irradiation of 2-diazoacenaphthenones in cyclohexane, benzene, and tetrahydrofuran. Photolysis of 11d in benzene in the presence of O₂ yields the insertion-oxidation product 2-hydroxy-5,6-dinitro-2-phenylacenaphthenone (60). Photolyses of 11a-c in nitriles result in N₂ evolution and dipolar cycloaddition to give acenaph[1,2-d]oxazoles (41 and 61a,b). Acetylenes undergo thermal and photolytic cycloaddition/1,5-sigmatropic rearrangement reactions with 11a-d with N₂ retention to give pyrazolo[5,1-a]quinolin-7-ones (69f-j). 2-Diazoacenaphthenones 1a and 11a react thermally and photolytically with electronegatively-substituted olefins with N₂ expulsion to yield (E)- and (Z)-2-oxospiro[acenaphthylene-1(2H),1′cyclopropanes] 73a-c and 74a-c, respectively. The mechanisms of the reactions of la, 11a-d, and 12 reported are discussed.

Full text of DOI:10.1021/jo040175h

P h otolytic, Th er m a l, Ad d ition , a n d Cycloa d d ition Rea ction s of
2-Dia zo-5,6- a n d -3,8-d isu bstitu ted Acen a p h th en on es
Patricia A. Blair, Sou-J en Chang, and Harold Shechter*
Department of Chemistry, The Ohio State University, Columbus, Ohio 43210
shechter@chemistry.ohio-state.edu
Received April 15, 2004
Preparation and varied thermal and photolytic reactions of 2-diazo-5,6-(disubstituted)acenaph-
thenones (11a -d ) and 2-diazo-3,8-dimethoxyacenaphthenone (12) are reported. Alcohols react
thermally and photolytically with 11a -c with losses of N2 to yield 2-alkoxynaphthenones (24a ,b
and 47a ,b) and acenaphthenones (25 and 48a ,b). Aniline and diphenylamine are converted by
11a -c at 180 °C to acenaph[1,2-b]indoles (29a ,b and 53a ,b). Thermolyses of 11a -c at ∼450 °C
(0.15 mmHg) yield reduction products 25 and 48a ,b, respectively. Wolff rearrangements to 1,8-
naphthyleneketenes (15a -d ) and/or their derivatives are not observed in the above experiments.
Oxygen converts 11a -c thermally to acenaphthenequinones (19a -c) and/or 1,8-naphthalic
anhydrides. Insertion, addition, substitution, and/or isomerization reactions occur upon irradiation
of 2-diazoacenaphthenones in cyclohexane, benzene, and tetrahydrofuran. Photolysis of 11d in
benzene in the presence of O2 yields the insertion-oxidation product 2-hydroxy-5,6-dinitro-2-
phenylacenaphthenone (60). Photolyses of 11a -c in nitriles result in N2 evolution and dipolar
cycloaddition to give acenaph[1,2-d]oxazoles (41 and 61a ,b). Acetylenes undergo thermal and
photolytic cycloaddition/1,5-sigmatropic rearrangement reactions with 11a -d with N2 retention
to give pyrazolo[5,1-a]quinolin-7-ones (69f-j). 2-Diazoacenaphthenones 1a and 11a react thermally
and photolytically with electronegatively-substituted olefins with N2 expulsion to yield (E)- and
(Z)-2-oxospiro[acenaphthylene-1(2H),1′cyclopropanes] 73a -c and 74a -c, respectively. The mech-
anisms of the reactions of 1a , 11a -d , and 12 reported are discussed.
In tr od u ction
6-nitro-2-oxoacenaphthenylidene (3b) as generated by
heating or photolytically in solution or thermally at
reduced pressures from 1b does not isomerize to 4-nitro-
1,8-naphthaleneketene (4b) or give products from 5-nitro-
2-oxoacenaphthenylidene (6) as formed from oxirene 5a
by rearrangement.1l,3 The inabilities of syn-R-diazo-
Photolytic, thermal, acid- and metal-ion catalyzed, and
cycloaddition reactions of 2-diazoacenaphthenone (1a )1a-o
and 2-diazo-5-nitroacenaphthenone (1b)1l have been re-
ported. Important with respect to the need for improved
syntheses of 1H-cyclobuta[de]naphthalenes (2)2 and prac-
tical preparative methods for decomposing stable R-di-
azoketones thermally or photolytically in solvents or in
the gas phase at various temperatures and pressures is
that 2-oxoacenaphthenylidene (3a ) as formed under such
conditions from 1a does not undergo Wolff rearrange-
ment3 to 1,8-naphthaleneketene (4a ).1a-d,l-o Further,
(1) (a) Horner, L.; Kirmse, W.; Muth, K. Chem. Ber. 1958, 91, 430.
(b) Cava, M. P.; Litle, R. L.; Napier, O. R. J . Am. Chem. Soc. 1958, 80,
2257. (c) Ried, W.; Lohwasser, H. J ustus Liebigs Ann. Chem. 1965,
683, 118. (d) DeJ ongh, D. C.; Van Fossen, R. Y. Tetrahedron 1972, 28,
3603. (e) Tsuge, O.; Shinkai, M.; Koga, M. J . Org. Chem. 1971, 36,
745. (f) Yamazaki, T.; Shechter, H. Tetrahedron Lett. 1972, 4533. (g)
Bannerman, C. G. F.; Cadogan, J . I. G.; Gosney, I. G.; Wilson, N. H. J .
Chem. Soc., Chem. Commun. 1975, 618. (h) Tsuge, O.; Koga, M.
Heterocycles 1977, 6, 411. (i) Chapman, O. L. Chem. Eng. News 1978,
Sep 18, 17. (j) Chapman, O. L. Pure Appl. Chem. 1979, 51, 331. (k)
Okada, K.; Mukai, T. Tetrahedron Lett. 1980, 359. (l) Chang, S.-J .;
Ravi Shankar, B. K.; Shechter, H. J . Org. Chem. 1982, 47, 2226. (m)
Maier, G.; Reisenauer, H. P.; Sayrac, T. Chem. Ber. 1982, 115, 2192.
(n) Hayes, R. A.; Hess, T. C.; McMahon, R. J .; Chapman, O. L. J . Am.
Chem. Soc. 1983, 105, 7786. (o) McMahon, R. J .; Chapman, O. L.;
Hayes, R. A.; Hess, T. C.; Krimmer, H. P. J . Am. Chem. Soc. 1985,
107, 7597.
(2) For present methodologies for preparing 1H-cyclobuta[de]naph-
thalenes and their cyclobuta derivatives, see: Engler, T. A.; Shechter,
H. J . Org. Chem. 1999, 64, 4247 and references therein.
ketones 1a 4 and 1b4 to rearrange to ketenes 4a and 4b,
respectively, in the above experiments are interpreted
10.1021/jo040175h CCC: $27.50 © 2004 American Chemical Society
Published on Web 09/23/2004
J . Org. Chem. 2004, 69, 7123-7133
7123

Blair et al.
to arise from strains in singlet state (S1) isomerizations
13a -d , respectively, and the crowding effects of the ortho
(3,8)-dimethoxy groups in 14 might lead to Wolff rear-
rangements by compressing, twisting, and reducing the
stabilizing delocalizations in their 5-membered ring,
R-ketocarbenyl moieties, and subsequent strain accom-
modation.6 Conversions to ketenes 15d and/or 16, re-
spectively, should also be facilitated by the enhanced
electron deficiency at the carbene center in 13d arising
from its 5,6-dinitro groups and/or by the increased
migratory ability of the naphthyl group in 14 resulting
from electron donation by its 3-methoxy group. As will
be described, the 5,6- and/or the 3,8-disubstituent effects
in 11a -d and 12, respectively, do not lead to preparative
syntheses of ketenes 15a -d and 16 and/or their deriva-
tives. The facts that 11a -d and 12 do not undergo
thermal and photolytic Wolff rearrangements readily
allow the diazo compounds to be used effectively for
valuable and certain unique syntheses. The studies also
provide information with respect to the generation,
behavior, and mechanisms of various reactions of non-
rearranging syn-R-oxocarbenes 13a -d and 14. Prepara-
tion and the varied chemistries of 2-diazoacenaph-
thenones 11a -d and 12 are now described.
of 3a and 3b as in 7a and 7b.1l,n,o In a profound series of
mechanism studies, Chapman et al. have found that
photolysis (365 ( 8 nm) of 1a in frozen argon at 10-15
°K gives triplet 2-oxoacenaphthenylidene [8, T°] as as-
signed spectrally and which is converted by matrix O2 to
1,8-naphthalic anhydride.1i,j,n,o Matrix irradiation (625 (
8 nm) of triplet 2-oxocarbene 8, after generation from 1a
in solid argon at 10-15 K, then yields naphthaleneketene
4a as assigned in the matrix by IR methods.1j,n,o Oxirene
5b is not detected spectrally.1j,n,o Photolytic ring contrac-
tion of oxocarbene 3a in matrix to ketene 4a is inter-
preted to arise from in-planar Wolff rearrangement of
the excited carbene in its S111 singlet state (9 and 10).1n,o
Studies are now reported of the syntheses and various
reactions of 2-diazo-5,6-dimethylacenaphthenone (11a ),
2-diazo-5,6-diphenylacenaphthenone (11b), 2-diazo-5,6-
di(m-tolyl)acenaphthenone (11c), 2-diazo-5,6-dinitro-
acenaphthenone (11d), and 2-diazo-3,8-dimethoxyacenaph-
thenone (12). Of interest is whether 5,6- (13a -d ) and-
(or) 3,8-disubstituted (14) 2-oxoacenaphthenylidenes as
generated thermally, photolytically, or catalytically in
solution or by low-pressure pyrolyses of 11a -d and 12,
respectively, convert preparatively to their corresponding
ketenes, 15a -d and 16, and/or products thereof.5 Repul-
sion interactions between the peri 5,6-dimethyl, -diphen-
yl, -di(m-tolyl), and -dinitro substituents in carbenes
(3) Wolff rearrangements and related chemistry of R-diazoketones
have been reviewed by: (a) Kirmse, W. Eur. J . Org. Chem. 2002, 2193.
(b) Toscano, J . P. In Advances in Carbene Chemistry; Brinker, V. H.,
Ed.; J AI Press, Inc.: Stamford, CT, 1998; Vol. 2, p 215. (c) Tidwell, T.
T. Ketenes; Wiley: New York, 1995; p 77. (d) Zollinger, H. Diazo
Chemistry II; VCH: Weinheim, 1995; p 344. (e) Ye, M. A.; McKervey,
A. Chem. Rev. 1994, 94, 1091, (f) Gill, G. B. In Comprehensive Organic
Synthesis; Trost, B. M., Fleming, I., Pattenden, G., Eds.; Pergamon:
Oxford, 1991; Vol. 3, p 887 and (g) references therein.3a,g
(4) (a) In concerted Wolff rearrangements R-diazoketones of s-Z
stereochemistry are believed to react more rapidly than their s-E
conformers because the migrating group attacks preferentially the
carbon atom bonded to the diazo group from the backside from which
nitrogen is expelled.4b,c (b) Kaplan, F.; Meloy, G. K. J . Am. Chem. Soc.
1966, 88, 950. (c) Kaplan, F.; Mitchell, M. L. Tetrahedron Lett. 1979,
759. (d) For summaries and discussions of steric aspects and mecha-
nism complications in decompositions and in Wolff rearrangements of
R-diazocarbonyl compounds, see ref 3a,b and references therein. (c) In
Wolff rearrangements of R-diazoaldehydes and ketones in the presence
of alcohols and amines, the migratory aptitudes of various groups may
be significantly affected by solvation or more intimate coordination of
the carbonyl groups of the R-diazo compounds with the nucleophilic
solvents.4d (d) J ordon, D. M. Ph.D. Dissertation, The Ohio State
University, Columbus, OH, 1965.
Resu lts a n d Discu ssion
Syn th eses of 11a-d an d 12. 2-Diazoacenaphthenones
11a -d 7,8 and 127,8 are presently prepared efficiently by
reactions of NaOH or NaOCH3 in CH2Cl2 with acenaph-
thenequinone mono-p-tosylhydrazones 17a -d 8 and 18,8
respectively, as obtained from acenaphthenequinones
19a -d and 208 with p-tosylhydrazine (1.0 equiv) in
refluxing CH3OH. The 2-diazoacenaphthenones are stable,
high-melting solids and can be recrystallized from hot
CH3CN, benzene, and toluene in ordinary light without
decomposition. Acenaphthenequinones 19a -c8 and 20,8
(5) (a) Many examples of cyclic R-diazoketones that undergo Wolff
rearrangements to yield highly strained, small-ring ketenes and/or
their derivatives are given in ref 3a-e. (b) Photosensitization elimi-
nates or greatly minimizes Wolff rearrangements of R-diazocarbonyl
compounds,3,5c and thus, such methodologies have not been presently
investigated for decompositions of 1a ,b, 11a -d , and 12. (c) Padwa,
A.; Layton, R. Tetrahedron Lett. 1965, 2167.
7124 J . Org. Chem., Vol. 69, No. 21, 2004

2-Diazo-5,6- and -3,8-disubstituted Acenaphthenones
SCHEME 1
respectively, are obtained by condensations of 1,8-di-
methyl- (21a ), 1,8-diphenyl- (21b), 1,8-di(m-tolyl)- (21c),
and 2,7-dimethoxynaphthalenes (22), respectively, with
oxalyl chloride (>2 equiv) and AlCl3 (>2 equiv) in CS2 at
-78 to +25 °C. Dinitration [HNO3(>2 equiv)/H2SO4] of
acenaphthenequinone (19e) at 0 °C yields 5,6-dini-
troacenaphthenequinone (19d ).9
(15a ) that then undergoes additions of the solvents.
Photolysis of 11a (medium-pressure Hg lamp) in CH3-
OH (23a ) at 25 °C under N2 through Pyrex occurs
smoothly, however, with loss of N2 to give (Scheme 1)
2-methoxy-5,6-dimethylacenaphthenone (24a , >61%) and
the reduction product 5,6-dimethylacenaphthenone (25,
>9%).8 Methyl 4,5-dimethyl-1H-cyclobuta[de]naphtha-
lene-1-carboxylate (26a , Scheme 1), the product expected
by addition of 23a to ketene 15a if generated, is not
detected (see the Experimental Section and Supporting
Information). Formation of 2-methoxyacenaphthenone
24a (R ) CH3) is presumed to occur by (1) reaction(s) of
CH3OH (23a ) with excited 11a with loss of N2 and/or (2)
loss of N2 and then reaction(s) of singlet carbene 13a with
23a . The photolytic reduction product, 5,6-dimethyl-
acenaphthenone (25), from 11a and 23a is apparently
produced by hydrogen abstraction reactions of excited
11a and/or carbene 13a as triplets (T°) with 23a , the
hydroxymethyl radical (•CH2OH) after formation from
23a , reaction product 24a , and/or initial 11a to give
2-oxoacenaphthenyl radical 27 which then abstracts
hydrogen from (any of) the above hydrogen atom donors.
Rea ction s of 11a -d a n d 12. Initial efforts in the
present studies involved possible practical photo- and
thermal-Wolff rearrangements of 5,6-dimethyl-R-diazo-
ketone 11a in alcohol and in amine solvents at various
temperatures to give 4,5-dimethyl-1,8-naphthaleneketene
(6) (a) X-ray structural analyses reveal peri effects of hydrogens in
naphthalene (A) and of methyl groups in 1,8-dimethylnaphthalene (B)
as shown.6b The carbon skeleton in B is essentially planar with no
bending of its methyl groups out of the plane of its naphthalene ring.6b
The C(1)-C(9)-C(8) bond angle in B is 125.2°.6b (b) Bright, D.; Maxwell,
I. E.; de Boer, J . J . Chem. Soc., Perkins Trans. 2 1973, 2101. (c) Of
note with respect to possible conversions of 1a ,b, 11a -d , and 12 to
cyclobutaketenes 4a ,b, 15a -d , and 16, respectively, is that 1-alky-
lidene-1H-cyclobuta[de]naphthalenes are preparable and quite stable.6d
In crystalline 1-(diphenylmethylene)-1H-cyclobuta[de]naphthalene (C),
the bond angles in its C(1a)-C(1)-C(7a) and C(1a)-C(8)-C(7a) units
are ca. 86° and 98°, respectively, the cyclobuta bond distances for C(1)-
C(1a) and C(1)-C(7a) are only 1.53-1.54 Å and thus shorter (∼ 0.03
Å) than such bonds in planar cyclobutanes, and, of particular signifi-
cance, its C(4)-C(9)-C(5) bond angle is 137°.6e Also, the C(4)-C(9)-
C(5) angle in 1-bromo-1H-cyclobuta[de]naphthalene is 138°.6f The
abilities of naphthalene rings to adjust to strains from peri-cyclobuta
interactions are impressive. (d) Card, P. J .; Friedli, F. E.; Shechter,
H. J . Am. Chem. Soc. 1983, 105, 6104. (e) Kumar, A.; Friedli, F. E.;
Hsu, L.; Card, P. J .; Mathur, N.; Shechter, H. J . Org. Chem. 1991, 56,
1663. (f) Gessner, M.; Card, P.; Shechter, H.; Christoph, G. J . Am.
Chem. Soc. 1977, 99, 2371.
In further attempts to bring about Wolff rearrange-
ment to ketene 15a and minimize reduction to dimethyl-
acenaphthenone 25, 11a was photolyzed in tert-butyl
alcohol [23b, R ) (CH3)3C]. Capture product, 2-tert-
butoxy-5,6-dimethylacenaphthenone [24b, R ) C(CH3)3,
Scheme 1, 22%],8 reduction product 25 (Scheme 1, 23%),
and intractables are obtained, however. There is no
evidence for formation of tert-butyl 4,5-dimethyl-1H-
cyclobuta[de]naphthalene-1-carboxylate (26b, Scheme 1)
from ketene 15a and alcohol 23b [R ) (CH3)3C] in these
experiments. Photolysis of 11a in tert-butyl alcohol (23b)
to give 25 (Scheme 1) as a major product is of interest.
Since tert-alcohol 23b is expected to be a poor hydrogen-
transfer reagent, formation of reduction product 25 is
presumed to arise primarily upon hydrogen abstraction
reactions of photolysis triplet 11a and/or triplet carbene
13a (T°) with capture product 24b [R ) C(CH3)3] and/or
(7) The syntheses of 11a -d and 12 from mono-p-tosylhydrazones
17a -d and 18, respectively, are extensions of that for 1a and 1b in
ref 1b and 1l, respectively.
(8) The products designated are of proper elemental analyses and
spectra (mass, IR, and NMR). See the Experimental Section or
Supporting Information.
(9) (a) Ruhemann, S. Chem. Ber. 1920, 52B, 287. (b) Rowe, F. M.;
Davis. J . H. S. J . Chem. Soc. 1920, 1344.
J . Org. Chem, Vol. 69, No. 21, 2004 7125

Blair et al.
SCHEME 2
initial R-diazoketone 11a . Of relevance, as will be detailed
later, is that photolysis of 11a in cyclohexane results in
carbenic C-H insertion into the solvent rather than
reduction (dihydrogen abstraction) to give 25.
R-Diazoketones in alcohols frequently undergo Wolff
rearrangements to ketenes at elevated temperatures4c
and as catalyzed by silver ion.3 The ketenes generated
are then usually efficiently trapped by the alcohols. In
present studies, R-diazoketone 11a reacts slowly in
refluxing CH3OH (23a , R ) CH3) and in refluxing 23a
containing silver oxide to yield (Scheme 1) the CH3OH
capture product 24a and reduction product 25. Methyl
dimethylcyclobutacarboxylate 26a (Scheme 1) is not
obtained. Further, decompositions of 11a in cyclohexanol
at 140 °C or in benzyl alcohol at 180 °C do not yield
cyclohexyl or benzyl 4,5-dimethyl-1H-cyclobuta[de]naph-
thalene-1-carboxylates, products derivable from additions
of the alcohols to ketene 15a .
Thermolyses of 11a were then conducted in solution
in primary and in secondary amines at elevated temper-
atures (140-180 °C) in efforts to generate and convert
ketene 15a to its corresponding 4,5-dimethyl-N-substi-
tuted 1H-cyclobuta[de]naphthalene-1-carboxamides (28).
Reactions of 11a in refluxing aniline (bp 184 °C) under
N2 which are not completely free of O2 give, however, 3,4-
dimethylacenaphth[1,2-b]indole (29a , > 27%),8 5,6-di-
methylacenaphthenequinone (19a , 32%), and intrac-
tables. Formation of 29a is the first example of reaction
of an R-diazoketone with an aniline to give an indole.
lecular ortho ring-closure with elimination of H2O. Indole
29a and acenaphthenequinone 19a are also obtained
upon photolysis of 11a in aniline in which O2 is present.
Quinone 19a is presumed to be formed (Scheme 2) by
reaction(s) of O2 with 11a and/or its subsequent carbene
(13a ) in its triplet state to give R-ketodioxirane 33, which
then oxidizes 11a and/or carbene(s) 13a . No attempts
have been made to increase the yields of indole 29a by
thermolysis or photolysis of 11a in aniline in which O2
is totally absent.
Of further interest is that reactions of 11a with molten
diphenylamine at 295 °C yield 3,4-dimethyl-N-phenyl-
acenaphth[1,2-b]indole (29b)8 and reduction (dihydrogen
abstraction) product, acenaphthenone 25. Reaction of
diphenylamine, a secondary amine, with 11a to yield 29b
cannot occur upon initial elimination of H2O to give Schiff
base intermediates as considered for aniline and 11a .
Indole 29b is presumed to be obtained thermally by (1)
loss of N2 from 11a , insertion of carbene 13a into the
N-H bond in diphenylamine to give R-aminoketone 32b
and its tautomers, and then heterocyclization by elimina-
tion of H2O and/or (2) nucleophilic addition of diphenyl-
amine to 11a to yield (E)- and (Z)-aminoazo intermedi-
ates which lose nitrogen to form 32b and/or its tautomers
followed by dehydrative indolization. Reduction product
25 is possibly formed by hydrogen atom transfer to the
2-oxoacenaphthenyl radical (27) as generated by hydro-
gen abstraction processes similar to those proposed for
photolyses of 11a in 23a and 23b and/or by homolytic
decomposition of the 32b (R ) C6H5) initially produced
thermally from 11a and diphenylamine with loss of N2.
Photolyses of 11a in very poorly nucleophilic solvents
were then investigated. Irradiation of 11a in cyclohexane
yields 2-cyclohexyl-5,6-dimethylacenaphthenone (34, 70%).8
Ketone 34 is presumably formed by insertion of carbene
13a in its singlet state into a C-H bond of cyclohexane.
There is no evidence for generation of ketene 15a in these
experiments. Reduction product 25a is not detected.
4,5-Dimethyl-N-phenyl-1H-cyclobuta[de]naphthalene-
1-carboxamide (28; R1 ) H, R2 ) C6H5) is not a reaction
product. At temperatures of ∼80 °C for 48 h, diazoketone
11a is stable and does not react with aniline. 1-Diazo-
5,6-dimethyl-2-phenyliminoacenaphthalene (30) and/or
its ring-closure isomer, 3,4-dimethylacenaphth[4,5-b]-
N(1)-phenyl-1,2,3-triazole (31), products expected upon
addition-elimination reactions of the carbonyl group in
11a with the amino group in aniline at 80 to ∼184 °C,
are not found. Formation of indole 29a apparently occurs
upon reaction of 11a with heated aniline and then loss
of N2 and/or decomposition of 11a to 13a followed by
carbenic insertion into the amino group in aniline to give
32a (R ) H) and its tautomers that undergo intramo-
Further, irradiation of 11a in benzene (Scheme 3) gives
(E)-cis-5,6-dimethylspiro[acenaphthene-1,7′-[2,4]norcara-
diene]-2-one (35, 20%),10 5,6-dimethyl-2-phenylacenaph-
thenone (36, 20%),8 and cis-7a,11a-dihydro-3,4-dimeth-
ylacenaphtho[1,2-b]benzo[d]furan (37, 40%).8 Ketene 15a
and/or its products are not observed. Spironorcaradiene
7126 J . Org. Chem., Vol. 69, No. 21, 2004

2-Diazo-5,6- and -3,8-disubstituted Acenaphthenones
SCHEME 3
isoxazole 43 are not found in any of the present experi-
ments.
Possible thermal conversions of 1a to ketene 4a have
been previously investigated.1c,d Decomposition of molten
1a at 160 °C yields (E)-[∆1,1]biacenaphthene-2,2′-dione
(45, 75%).1c,d Gas-phase decomposition of 1a at 400 °C
gives intractables.1c,d Ketene 4a and/or its transformation
products are not found in these experiments.1c,d Study
has now been made of the behaviors of 11a and 1a ,
respectively, upon dropping the finely ground, solid
2-diazoacenaphthenones at various rates directly into
vertical, packed quartz tubes at 0.15 mm Hg pressure
and 450 °C and rapidly condensing the volatile products
at -78 °C or in CH3OH (23a ) at <-78 °C. Such vacuum
pyrolyses of 11a give the reduction product, 5,6-dimethyl-
acenaphthenone (25, 14%), and non-chromatographable
materials. Further, vacuum thermolyses of 1a at 450 °C/
0.10 mm Hg as above result in formation of the reduction
product, acenaphthenone (45, 16%), and intractables.
There is no evidence in the present decomposition or
capture experiments (see the Experimental Section) for
conversions of (1) 11a to ketene 15a or cyclobuta ester
26a and/or (2) 1a to ketene 4a or methyl 1H-cyclobuta-
[de]naphthalene-1-carboxylate (46).13 As will be de-
scribed, reduction (double hydrogen transfer) reactions
also occur in decompositions of 11b and of 11c upon being
heated to ∼450 °C at 0.10-0.15 mm Hg pressures as for
11a .
35 is thermally unstable and converts quantitatively to
36 on standing and in refluxing xylenes. Photolysis of
11a in benzene to give 35, 36, and 37 and isomerization
of 35 to 37 provide additional information as to the
behaviors of 2-oxoacenaphthenylidenes with benzene in
that it has been previously reported that irradiation of
(1) 1a in benzene yields (E)-spironorcaradiene adduct 38
(84%) which is isomerized by acids or silver ion to
2-phenylacenaphthenone (39)1g and (2) 1b in benzene
results in aromatic substitution of the solvent to give
5-nitro-2-phenylacenaphthenone (40, 55%).1l The fact that
spironorcaradiene 38 is more stable thermally than 35
suggests that the peri-methyl groups in 35 cause desta-
bilization, presumably by the steric compression and
twisting in its spironorcaradiene section. In the present
experiments formation, without catalysis, of 36 and 37,
both of which should be less strained than 35, is thus
facilitated.
Of value with respect to synthesis and reaction mech-
anism is that photolysis of 11a in CH3CN yields 3,4,8-
trimethylacenaph[1,2-d]oxazole (41, 52%)8,11 presumably
as formed by addition of excited 11a to the nitrile, loss
of N2, and ring-closure, and/or generation and then
reaction(s) of oxocarbene 13a with the cyano group of the
CH3CN.12 Ketene 15a or its derivatives, azirene 42, or
(10) (a) Because of its instability and difficulties in its separation
from 36 and 37, (E)-35 was not isolated analytically pure. The
assignment of the product as (E)-35 rather than D is based on its IR
and mass spectra, its NMR spectrum as compared to that of (E)-38 as
prepared by photolysis of 1a in benzene,1g and expectation that,
because of steric effects from the carbonyl group(s) in carbene(s) 13a ,
addition of the carbene(s) to a double bond in benzene will occur
preferentially to give the cyclopropane now reported. (b) Reference 1g
has emphasized that Ha in 30 is highly shielded and exhibits NMR
absorption at 6.8-6.9 δ.
Studies were then initiated of the photolytic and
thermal behaviors of 11b and 11c.7 Of importance is
(12) Many reactions of 11a -d of the present studies with nitriles,
acetylenes, and olefins involve possible 1,3-dipolar and related cy-
cloaddition processes. For comprehensive reviews of such reactions of
diazo compounds see (a) Huisgen, R. In 1,3-Dipolar Cycloaddition
Chemistry; Padwa, A., Ed.; Wiley: N. Y., 1984; Vol. 1, pp 1-176. (b)
Regitz, M.; Heydt, H. In 1,3-Dipolar Cycloaddition Chemistry; Padwa,
A., Ed.; Wiley: New York, 1984; Vol. 1, pp 393-558. (c) Maas, G. In
Synthetic Applications of 1,3-Dipolar Cycloaddition Chemistry Toward
Heterocycles and Natural Products; Padwa, A., Pearson, W. A., Eds.;
Wiley: New York, 2002; pp 539-622 and (d) references therein.
(13) Ester 46 is prepared6d by (1) photolysis of 8-bromo-1-naphth-
yldiazomethane, (2) reaction of the resulting 1-bromo-1H-cyclobuta-
[de]naphthalene with Mg, (3) conversion of the Grignard reagent
formed by CO2 and then acidification to 1H-cyclobuta[de]naphthalene-
1-carboxylic acid, and (4) esterification of the carboxylic acid with
diazomethane.
(11) (a) Important to the assignment is that 41 does not exhibit IR
absorption for a carbonyl group and its methyl group has the same
NMR chemical shift, δ ) 2.61, as that in 8-methylacenaphth[1, 2-d]-
oxazole.1l,11b (b) Ibata, T.; Sato, R. Chem. Lett. 1978, 10, 1129.
J . Org. Chem, Vol. 69, No. 21, 2004 7127

Blair et al.
whether the steric repulsions of the peri-phenyl groups
in 11b and/or the peri-m-tolyl groups in 11c are sufficient
to compress, twist, and strain the diazoketone moieties
in the 2-diazoacenaphthenones such that photolytic losses
of N2 and ring-shrinking rearrangements to ketenes 15b
and/or 15c will occur. Photolysis of 11b in CH3OH (23a )
yields, however, the 23a capture product 2-methoxy-5,6-
diphenylacenaphthenone (47a , 33%)8 and the reduction
(dihydrogen transfer) product 5,6-diphenylacenaph-
thenone (48a , 15%).8 Similarly, irradiation of 11c in 23a
gives 2-methoxy-5,6-di(m-tolyl)acenaphthenone (47a, 36%)8
and 5,6-di(m-tolyl)acenaphthenone (48b, 16%).8 Pho-
tolytic conversions of 11b and 11c, respectively, in 23a
to ketenes 15b and 15c and/or their CH3OH adducts 49a
and 49b are not observed. The behaviors of 11b and 11c
upon irradiation in 23a are thus essentially identical with
that of 11a under similar conditions.
which O2 is deliberately added gives N,4,5-triphenyl-1,8-
naphthalimide (55, 15%)8 along with indole 53a . In no
experiment is carboxamide 56a , as possibly formed from
ketene 15a and aniline, found. The thermal and the
photolytic behaviors of the 11b/aniline system are very
sensitive to O2 even in trace amounts. Anhydride 54 is
presumed to be formed by rearrangement of dioxirane
57a as produced thermally from 11b and O2. Anthraquino-
ne 19b apparently results from thermal reactions of
dioxirane 57a and/or O2 with 11b and/or its carbenes
(13b). Naphthalimide 55 as obtained photochemically
from 15b, aniline, and O2 presumably arises by reaction
of aniline with anhydride 54 and/or rearrangement of
oxazirane 58 as generated from aniline and dioxirane
57a .
Photolyses of 11b and 11c, respectively, in benzene
were then investigated. Irradiation of 11b in benzene
yields the carbenic capture products: 2,5,6-triphenyl-
acenaphthenone (50a , 25%)8 and cis-7a,11a-dihydro-3,4-
diphenylacenaphtho[1,2-b]benzo[d]furan (51a , 44%);8 cis-
5,6-diphenylspiro[acenaphthene-1,7′-[2,4]norcaradiene]-
2-one (52a ), ketene 15b, and reduction product 48a are
not found. In present experiments essentially identical
with that described earlier for 11a , photolysis of 11c in
benzene gives 2-phenyl-5,6-di(m-tolyl)acenaphthenone
(50b, 13%),8 cis-7a,11a-dihydro-3,4-di(m-tolyl)acenaph-
tho[1,2-b]benzo[d]furan (51b, 39%),8 and reduction prod-
uct 48b (13%); spironorcaradiene 52b and ketene 15c are
not obtained. Because of its strain 52b, if formed, is
expected to isomerize readily to 50b and/or 51b. As in
photolysis of 11a in benzene to give reduction (dihydro-
gen abstraction) product 25, there are many routes by
which 48b might be formed upon photolysis of 11c in
benzene.
Of further interest is that heating 11c with aniline at
180 °C under N2 in which a trace of O2 is present yields
3,4-di(m-tolyl)acenaph[1,2-b]indole (53b, 36%)8 and 5,6-
di(m-tolyl)acenaphthenequinone (19d , 32%). Carbox-
amide 56b is not obtained. The reactions of 11c are thus
similar to that of 11b and 11a with aniline/O2 at 180 °C.
Formation of indoles 29a , 53a , and 53b, respectively,
from thermal reactions of 11a -c with aniline is of
synthesis value.
The behaviors of 11b and 11c at high temperatures,
short contact times, and reduced pressures were then
determined. As discussed previously for 11a and 1a ,
finely ground solid 11b and 11c were each dropped
directly into evacuated quartz tubes at ∼450 °C/0.15 mm
Hg pressure, and the exit products were condensed
rapidly at -78 °C or in 23a at -78 °C and separated and/
or analyzed by chromatographic methods. Such decom-
positions of 11b and 11c give the reduction (double
hydrogen abstraction) products 48a (7%) and 48b (11%),
respectively, along with inseparable, complicated materi-
als. The above thermolyses of 11b and 11c give no
evidence for formation of ketenes 15b and 15c and/or
their respective ketene-CH3OH adducts 49a and 49b. As
in pyrolysis of 1a to reduction product 45, thermolysis
of 11b requires transfer of two hydrogen atoms by two
or more molecular events to yield 48a .
Investigations of thermal and photolytic reactions of
11b and of 11c were continued. Heating 11b in refluxing
aniline (∼180 °C) under N2 in which O2 is not completely
purged yields 3,4-diphenylacenaphth[1,2-b]indole (53a ,
17%)8 along with 4,5-diphenyl-1,8-naphthalic anhydride
(54, 20%)8 and 5,6-diphenylacenaphthenequinone (19b,
48%). Further, irradiation of 11b in aniline at ∼25 °C in
Various nitrogen-extrusion reactions of 11d were then
investigated. Diazodinitroacenaphthenone 11d is a high-
melting solid (mp 234-236 °C) that decomposes with
7128 J . Org. Chem., Vol. 69, No. 21, 2004

2-Diazo-5,6- and -3,8-disubstituted Acenaphthenones
evolution of N2 on melting, vacuum pyrolysis, and
thermally and photolytically in solution in various sol-
vents. Thermolyses and photolyses of 11d do not give
cyclobutaketene 15d . Photolyses of benzene solutions of
1b under N2 containing small amounts of O2 yield 5-nitro-
2-phenylacenaphthenone (35a );1l under similar condi-
tions, 11d gives 2-hydroxy-5,6-dinitro-2-phenylacenaph-
thenone (60)8 as a principal product (45%). Oxidation of
59b presumably yields 60. Of value for synthesis is that
photolyses of 11d in CH3CN and in benzonitrile occur
with loss of N2 to yield the products of cycloaddition-
capture by the nitrile groups: 8-methyl-(3,4-dinitro-
acenaphth)[1,2-d]oxazole (61a , 67%)8 and 3,4-dinitro-8-
phenylacenaphth[1,2-d]oxazole (61b, 26%),8 respectively.
5,6-Dinitro analogues of 42 and 43 are not detected.
of N2, or more likely, by photolytic conversion of 12 to
singlet carbene 14 followed by nucleophilic addition of
tetrahydrofuran. Photochemical nucleophilic-rearrange-
ment reactions similar to that for 12 with tetrahydro-
furan have been previously found for other R-diazocar-
bonyl compounds with oxiranes and other ethers.14 The
present photolytic reaction of 12 and tetrahydrofuran to
give 65 is significant in that coordinative electrophilic
attack on ethereal oxygen and rearrangement occur so
much more extensively than carbenic insertions into any
of the 8 carbon-hydrogen bonds of the cyclic ether.
The products and the mechanisms of thermal and
photolytic reactions of various 2-diazoacenaphthenones
with acetylenes continue to be of interest.12 2-Diazo-
acenaphthenone (1a ) is reported to react with diethyl
acetylenedicarboxylate and with phenylacetylene in re-
fluxing benzene by 1,3-dipolar cycloaddition processes to
yield spiro[acenaphthenone-2,3′-(3′H)-pyrazoles 68a (80%)
and 68b (25%), respectively.1e In studies in this labora-
tory, reactions of 1a with dimethyl acetylenedicarboxy-
late and phenylacetylene in refluxing benzene (bp 80 °C)
are found to give 7H-benzo[de]pyrazolo[5,1-a]isoquinolin-
7-ones 69c (89%) and 69b (82%), respectively.1l The
structures of the 69c and 69b as thus obtained are
established by independent syntheses of the isoquinolin-
7-ones, and the properties of the 69b prepared are
identical with that reported for 68b.1e Efforts to detect
68c and 68b as cycloaddition products in the above
experiments were unsuccessful.1l Spiropyrazoles 68c,
68b, and presumably 68a as formed by 1,3-dipolar
The thermal and the photolytic behaviors of 2-diazo-
3,8-dimethoxyacenaphthenone (12) were then investi-
gated. Diazoketone 12 does not convert to ketene 16,
insertion product 62, or products resulting from attack
on oxygen of its 3-methoxy group when heated as a solid,
on melting (mp 145-146 °C), or in solution. Photolysis
of 12 in CH3OH (23a ) yields 2,3,8-trimethoxyacenaph-
thenone (63, >78%)8 preparatively. Methyl 2,7-dimethoxy-
1H-cyclobuta[de]naphthalene-1-carboxylate (64) is not
detetected. A further example that 12 does not convert
to a Wolff rearrangement product readily is irradiation
of the diazoketone in tetrahydrofuran to give spiro[3,8-
dimethoxyacenaphthenone-2,2′-tetrahydropyran] (65)8 in
53% yield. Formation of 65 presumably occurs by (1)
nucleophilic reaction of tetrahydrofuran with excited
singlet 12 and decomposition with loss of N2 as in 66 and/
or (2) rearrangement of 67 as generated from 66 by loss
J . Org. Chem, Vol. 69, No. 21, 2004 7129

Blair et al.
cycloaddition reactions of dimethyl acetylenedicarboxy-
late, phenylacetylene, and diethyl acetylenedicarboxylate
with 1a are surmised to undergo rapid, thermally al-
lowed, and sterically-favored 1,5-sigmatropic rearrange-
ments to 69c, 69b, and 69a , respectively.1e Further,
dimethyl acetylenedicarboxylate and phenylacetylene
react with 1b in chlorobenzene at 130 °C to yield 69d
(83%) and 69e (68%), respectively, presumably by isomer-
izations of cycloadducts 68d and 68e as initially formed.1l
Studies have now been made of the addition reactions
of 2-diazoanthrones 11a -d with phenylacetylene and/
or dimethyl acetylenedicarboxylate in warm toluene
(∼111 °C) in efforts to control formation of spiropyrazoles
68 and isoquinolin-7-ones 69 by steric and/or electronic
effects. In all of the present experiments with 11a -d ,
the only products isolable are the respective isoquinolin-
7-ones 69f-j (74-100% yields)8 as presumably formed
by rearrangements of the initial spiropyrazoles 68f-j. Of
importance in these experiments is that (1) 2-diazoan-
thrones 11a -d react as 1,3-dipolar reagents expressed
as 70a -d to give 69f-j in excellent yields and (2) the
electron-attracting effects of the CO2CH3 groups in 68g-
j, the compressions caused by steric repulsions of the peri-
substituents in 68f-j, and the electron-donations to the
carbonyl groups by the Z1 substituents in 68f-i are
insufficient to stop formation of 69f-i.
with ethyl acrylate, highly electronegatively-substituted
olefins, with loss of N2 to give the corresponding (E)- and
(Z)-spiro[acenaphthenone-2,1′-cyclopropanes] 73a 15 and
74a 15 and 73b and 74b, respectively. Reactions of 1a with
acrylonitrile as catalyzed by palladium acetate yield 73a
and 74a more rapidly and in higher yields.1l Of impor-
tance with respect to preparation and mechanisms of
formation of cyclopropyl derivatives from 2-diazoacenaph-
thenones and olefins is that 11a does not react with
cyclohexene at 85 °C or on storage with the electron-rich
olefin, ethyl vinyl ether. Reactions of 11a occur efficiently,
however, with methyl acrylate at 80 °C (<12 h) and, of
mechanistic significance, at 20-25 °C (24 h) to give
methyl (E)- (73c, 50%) and (Z)--5,6-dimethyl-2-oxospiro-
[acenaphthylene-1(2H),1′-cyclopropane]-2′-carboxylates
(74c, 39%).16 Thus, 11a reacts as a nucleophile with
methyl acrylate at room temperature without initial loss
of N2. 1,3-Dipolar cycloadducts 75 are not detected as yet
however as reaction intermediates. That (E)- and (Z)-75
are not obtained as stable intermediates or that such
intermediates, if formed, undergo prototopic rearrange-
ments with retention of nitrogen allow simple syntheses
of 73c and 74c. An important aspect of nucleophilic
reactions of 1a and 11a with acrylonitrile and acrylic
esters is ready loss of N2 to give cyclopropane derivatives
which have bisected stereochemistries and are stabilized
by spiroconjugation.
Con clu sion s
Photolyses of 11a and 11d in phenylacetylene differ,
however, from thermolyses in that N2 is extruded and
net regiospecific cycloadditions occur to give acenaphtho-
[1,2-b]furans 71a (61%) and 71b (48%), respectively. The
overall photolytic reactions of 11a and 11d with phenyl-
acetylene and with CH3CN are thus similar. The photo-
chemical reactions of 11a and 11d are presumed to
involve generation of electrophilic carbenes 13a and 13d ,
respectively, which undergo net, directed 1,3-dipolar
reactions with phenylacetylene to yield 71a and/or 71b.
The R-oxocyclopropenes 72a and 72b, respectively, as
possibly formed by additions of 13a and 13d to phen-
ylacetylene, are not found as reaction intermediates but,
as yet, cannot be excluded as precursors to 71a and 71b.
Sterically strained 2-diazoacenaphthenones photolyze
in solution with loss of N2 and without rearrangement
in reactions with alcohols, cyclohexane, tetrahydrofuran,
benzene, nitriles, and acetylenes. Thermal decomposi-
tions of the 2-diazoacenaphthenones in solution or at low
pressures do not yield ketenes and/or products thereof
preparatively. Thermolyses of 2-diazoacenaphthenones
in aniline and in diphenylamine result in N2 loss from
the diazo compounds, insertions into the N-H groups of
the amines, ortho ring closures, and eliminations of H2O
to give novel acenaph[1,2-b]indoles (29a ,b and 54a ,b).
2-Diazoacenaphthenones react rapidly with O2 on heating
(14) (a) Nozaki, H.; Takaya, H.; Noyori, R. Tetrahedron Lett. 1965,
2563. (b) Nozaki, H.; Takaya, H.; Noyori, R. Tetrahedron 1966, 22,
3393. (c) Kirmse, W.; Lelgemann, R.; Friedrich, K. Chem. Ber. 1991,
124, 1853.
(15) Upon reinvestigation of their NMR, the spirocyclopropanes from
1a and acrylonitrile1e are reassigned stereochemically as 73a and 74a .1l
(16) Assignment of the structures of 73c and 74c have been made
upon comparison of their spectra with that of 73b and 74b as prepared
by heating 1a in ethyl acrylate.1l Spirocyclopropane 73b has IR
absorptions for its carbonyl groups at 1728 and 1710 cm-1 which
compare to 1730 and 1700 cm in 73c. The ABX patterns in the NMR
spectra of 73c and 73b are identical. Spirocyclopropane 74b exhibits
IR carbonyl absorptions at 1740 and 1713 cm-1 compared to 1745 and
1710 cm-1 in 74c. The ABX portions of the NMR of 74c and 74b are
identical. The actual values of the chemical shifts and coupling
constants of 73c and 74c are not calculated because portions of their
ABX patterns are buried beneath that for their peri-methyl groups.
Of further interest is that 1a reacts thermally (∼80
°C, 10 h)1h,l and photolytically1l with acrylonitrile and
7130 J . Org. Chem., Vol. 69, No. 21, 2004

2-Diazo-5,6- and -3,8-disubstituted Acenaphthenones
Cyclobuta ester 46 is readily detected spectrally in low
concentrations in admixture with its isomer,2-methoxyacenaph-
thenone, along with acenaphthenone. In photolyses of 11a in
23a and in 23b there is no spectral evidence for cyclobuta ester
26a and 26b, respectively, in the crude or the purified reaction
products. Similarly, spectral analyses of the products of
thermolyses of 11a in cyclohexanol at 240 °C and in benzyl
alcohol at 180 °C do not indicate the presence of cyclohexyl or
benzyl ester analogues of 26a and 26b. The MS, IR, and NMR
methods for 46 were also used to determine that Wolff
rearrangement products are not obtained from reactions of
11b-c and of 12 with alcohols. When these analytical methods
are extended to the products of reactions of 11a -c with
amines, there is no evidence for formation of amides resulting
from capture of ketenes arising from Wolff rearrangements.
and upon photolysis. In hydrogen-atom donor environ-
ments, thermal and photolytic reduction reactions of
2-diazoacenaphthenones may become prominent. Acety-
lenes undergo nucleophilic additions to 2-diazoacenaph-
thenones (1a ,b, 11a -c, and 12) with retention of N2 and
1,5-sigmatropic rearrangements to yield pyrazolo[5,1-a]-
quinolin-7-ones (69). Electronegatively-substituted olefins
such as methyl acrylate and acrylonitrile undergo ther-
mal and photochemical addition reactions of their olefinic
groups with 2-diazoacenaphthenones (1a and 11a ) with
loss of N2 and without rearrangements to give (E)- and
(Z)-spirocyclopropyl derivatives (73a -c and 74a -c).
Carbenic reactions of 2-diazo-5,6-bis(trisubstitutedsilyl)-
acenaphthenones and more highly compressed 2-diazo-
acenaphthenones are of present interest.
P h otolysis of 11a in Meth a n ol (23a ). A solution of 11a
(0.51 g, 2.3 mmol) in 23a (225 mL) was photolyzed 3 h. The
residue obtained upon removal of solvent under vacuum and
chromatography on silica gel (CH2Cl2/petroleum ether 1:1)
yielded two products:
Exp er im en ta l Section
5,6-Dim eth yla cen a p h th en equ in on e (19a ). Oxalyl chlo-
ride (5 mL, D ) 1.46, 57 mmol) was added to a stirred slurry
of AlCl3 (6.0 g, 45 mmol) in CS2 (30 mL) at -78 °C. Solid 1,8-
dimethylnaphthalene (2.5 g, 16 mmol)17 was then added. The
thick, dark-red solution was allowed to warm and then stirred
for 3 h at -10 °C and for 1 h at ∼25 °C, followed by slow
addition of H2O. The CS2 was removed by heating. The
resulting yellow solid was filtered, dried, and recrystallized
from toluene/CH3CN (1:1) to give 19a (1.8 g, 54%, mp 232-
235 °C) as long yellow needles: IR (KBr, cm-1) 1723, 1715 (C
) O, s); NMR (CDCl3, δ) 7.69 (d of d, 4H, naphthyl), 3.07 (s,
6H, 2 CH3); MS m/e 210 (M+). Anal. Calcd for C14H10O2: C,
79.99; H, 4.80. Found: C, 80.02; H, 4.91.
5,6-Dim et h yla cen a p h t h en eq u in on e 2-p -Tosylh yd r a -
zon e (17a ). p-Tosylhydrazine (9.75 g, 48 mmol) was added to
a suspension of 5,6-dimethylacenaphthenequinone (19a , 8.75
g, 42 mmol) in boiling CH3CN (200 mL). The resulting mixture
was refluxed 0.5 h. The yellow crystals obtained upon cooling
were filtered and dried to yield 17a (13.1 g, 83%, mp 121-
123 °C): IR (KBr, cm-1) 3193 (NH, w), 1681 (CdO, s), 1392,
1170 (SO2, s); NMR (CDCl3, δ) 8.37 (bs, 1H), 8.03-7.13 (m,
8H), 2.90 (d, 6H), 2.36 (s, 3H). Anal. Calcd for C21H18N2SO3:
N, 7.40; S, 8.47. Found: N, 7.25; S, 8.30.
2-Dia zo-5,6-d im eth yla cen a p h th en on e (11a ). A CH2Cl2
(90 mL) solution of 17a (1.58 g, 4.2 mmol) and aqueous NaOH
(46 mL, 0.1 N, 4.6 mmol) was vigorously stirred overnight. The
H2O layer was extracted several times with CH2Cl2. The
combined CH2Cl2 extracts were washed with H2O and dried
over Na2SO4. Removal of CH2Cl2 and chromatography (neutral
alumina, CH2Cl2) yielded 11a (0.73 g, 79%, mp 128-129 °C)
as light orange needles after recrystallization from toluene/
petroleum ether: IR (KBr, cm-1) 2085 (dN2, s), 1682 (CdO,
s); NMR (CDCl3, δ) 7.65 (d of d, 2H), 7.20 (d, 2H), 2.90 (d, 6H).
Anal. Calcd for C14H10N2O: C, 75.66; H, 4.54; N, 12.60.
Found: C, 75.41; H, 4.56; N, 12.37.
Sea r ch for Wolff Rea r r a n gem en t P r od u cts in Rea c-
tion s of 2-Dia zoa cen a p h th en on es 11a-c a n d 12, Resp ec-
tively, w ith Alcoh ols a n d Am in es. The reactions of 11a -c
and 12, respectively, with alcohols were carefully examined
for Wolff rearrangement products. Important to these analyses
is that methyl 1H-cyclobuta[de]naphthalene-1-carboxylate
(46)6d is a stable, chromatographable liquid prepared as in ref
13. The properties of 46 which are reliably determined are its
exact mass, its IR absorption for its ester carbonyl group at
1735 cm-1, and its NMR at δ ) 5.94 for one cyclobuta proton.6d
(1) 5,6-dimethylacenaphthenone (25, 50 mg, 9%, mp 164-
165 °C) obtained as pink crystals after recrystallization from
hexane: IR (KBr, cm-1) 1700 (CdO, s); NMR (CDCl3, δ) 7.90-
7.23 (m, 4H), 3.70 (s, 2H), 2.91 (d, 6H). Anal. Calcd for
C14H12O: C, 85.68; H, 6.16. Found: C, 85.42; H, 6.21 and (2)
2-methoxy-5,6-dimethylacenaphthenone (24a , 0.32 g, 61%, mp
130-131 °C) which was recrystallized from hexane to give pale
yellow crystals: IR (KBr, cm-1) 2815 (OCH3, w), 1718 (CdO,
s); NMR (CDCl3, δ) 7.90-7.23 (m, 4H), 5.00 (s, 1H), 3.57 (s,
3H), 2.93 (d, 6H). Anal. Calcd for C15H14O2: C, 79.62; H, 6.24.
Found: C, 79.49; H, 6.40. There was no evidence for 26a in
the reaction products.
P h otolysis of 11a in ter t-Bu tyl Alcoh ol (23b). Photolysis
of 11a (0.5 g, 2.2 mmol) in 23b (225 mL) was effected for 26 h.
Vacuum removal of the 23b yielded a brown semi-solid which
was chromatographed on silica gel (benzene). The first com-
pound eluted was reduction product 25 (0.1 g, 23%, mp 164-
165 °C) as characterized previously. The next compound eluted
was 2-tert-butoxy-5,6-dimethylacenaphthenone (24b, 0.13 g,
22%, mp 136-136.5 °C (benzene/petroleum ether) as off-white
needles: IR (KBr, cm-1) 1721 (CdO, s), no absorption assign-
able to 26b resulting from addition to 15a , the possible ketene,
from Wolff contraction of 11a ; NMR (CDCl3, δ) 7.77-7.13 (m,
4H), 5.10 (s, 1H), 2.89 (d, 6H), 1.49 (s, 9H); m/e calcd
for C18H20O2: 268.14632, obsd 268.14542. Anal. Calcd for
C
18H20O2: C, 80.56; H, 7.51. Found: C, 80.48; H, 7.71.
Th er m olysis of 11a in An ilin e. A solution of 11a (0.5 g,
2.2 mmol) in aniline (5 mL) was heated to 180 °C for 0.25 h
and then refluxed (∼ 180 °C) for 1 h. The dark red solution
was allowed to cool to room temperature, poured into a
concentrated HCl-ice slurry, and extracted with benzene. The
organic layer was dried over MgSO4 and concentrated to a dark
orange semisolid. Chromatography on silica gel (benzene)
yielded 3,4-dimethylacenaphth[1,2-b]indole (28, 0.16 g, 27%,
mp 272-274 °C (benzene)), as light orange crystals: IR (KBr,
cm-1) 3417 (NH, s); NMR (CDCl3, δ) 8.48 (bs, 1H), 7.96-6.93
(m, 8H), 2.83 (s, 6H); m/e calcd for C20H15N 269.12044, obsd
269.12112. Anal. Calcd for C20H15N: C, 89.19; H, 5.6; N, 5.20.
Found: C, 88.88; H, 5.75; N, 5.03. The second product isolated
was 25 (0.15 g, 32%, mp 232-235 °C) as previously character-
ized. [Similar results were obtained upon submerging a
solution of 11a in aniline in a silicone bath at 180 °C and
refluxing the mixture for 1 h.]
Th er m olysis of 11a in Dip h en yla m in e. Diphenylamine
(5 g) was melted (mp 54 °C) and 11a (0.3 g, 1.4 mmol) was
added. The mixture was heated for 10 min in a salt bath (47%
NaNO2, 7% NaNO3, 46% KNO3) at 295 °C and then cooled to
room temperature. Ethyl ether was added, and the dark red
solution was poured into a concentrated HCl-ice slurry. The
H2O layer was extracted several times with benzene. The
organic layer was dried over Na2SO4 and evaporated under
vacuum. The red, oily concentrate (5.27 g) was primarily
(17) (a) 1,8-Dimethylnaphthalene was prepared by (1) reduction of
1,8-naphthalic anhydride with LiAlH4 to 1,8-bis(hydroxymethyl)-
naphthalene,17b (2) conversion of the diol by PBr3 to 1,8-bis(bromometh-
yl)naphthalene,17c and (3) reaction of the dibromide with LiAlH4.17d
(b) Boekelheide, V.; Vick, G. K. J . Am. Chem. Soc. 1956, 78, 653. (c)
Mitchell, W. J .; Sondheimer, F. Tetrahedron 1968, 34, 1397. (d)
Mitchell, W. J .; Topsom, R. D.; Vaughan, J . J . Chem. Soc. 1940, 2526.
J . Org. Chem, Vol. 69, No. 21, 2004 7131

Blair et al.
diphenylamine and eventually solidified. Chromatography of
the solid concentrate on silica gel (benzene/petroleum ether
1:1) yielded 3,4-dimethyl-N-phenylacenaphth[1,2-b]indole (29b,
60 mg, 12%, mp 191-192 °C) which was recrystallized from
benzene:petroleum ether to give shiny red crystals: NMR
(CDCl3, δ) 8.23-7.23 (m, 13H), 3.03 (s, 6H); m/e calcd for
The 11a was dropped slowly into the pyrolysis tube by
gradually turning the scoop in the Erlenmeyer flask. The
condensable volatile products were collected in the receiving
flask and, after 30 min, the pyrolysis equipment was allowed
to cool. Anhydrous CH3OH (23a , 20 mL) was added to the
condensate at -78 °C in the receiving flask. The light orange
23a solution was allowed to warm to room temperature and
evaporated. Chromatography of the light orange film on
alumina (benzene) yielded 25 (40 mg, 14%, mp 164-165 °C),
identical with an authentic sample. There was much dark
material on the walls of the pyrolysis tube.
C
H
26H19N: 345.15174, obsd: 345.15257. Anal. Calcd for C26
-
19N: C, 90.40; H, 5.54; N, 4.06. Found: C, 90.38; H, 5.65; N,
3.96.
Diphenylamine, contaminated with a small amount of 29b,
was next eluted on chromatography (diphenylamine and 29b
have similar Rf values). Further elution produced 25 (20 mg,
7%, mp 164-165 °C) as characterized previously.
Similar results were obtained from vacuum pyrolysis of 11a
when 23a was placed in the receiving flask.
P h otolysis of 11a in Cycloh exa n e. Diazoacenaphthenone
11a (0.52 g, 2.3 mmol) in cyclohexane (225 mL) was photolyzed
3 h and then concentrated to dryness. Chromatography of the
crude product on silica gel (benzene) yielded 2-cyclohexyl-5,6-
dimethylacenaphthenone (34, 0.39 g, 70% based on reacted
starting material, mp 115-116 °C). Recrystallization of 34
from benzene:hexane (1:1) gave tiny orange crystals: IR (CCl4,
cm-1) 1712 (CdO, s); NMR (CDCl3, δ) 7.82-7.10 (m, 4H), 3.43
(d, 1H, J ) 1.5), 2.80 (d, H), 1.87-0.57 (bm, 11H); m/e calcd
P h otolysis of 11a in P h en yla cetylen e. A solution of 11a
(0.5 g, 2.2 mmol) in phenylacetylene (225 mL) was photolyzed
24 h. The phenylacetylene was removed under vacuum, leaving
a brown oil which was chromatographed on silica gel (benzene/
hexane 1:1) to give 3,4-dimethyl-8-phenylacenaphtho[1,2-b]-
furan (71a , 0.4 g, 61% based on reacted starting material, mp
186-188 °C) as orange crystals when recrystallized from
petroleum ether: NMR (CDCl3, δ) 7.93-7.12 (m, 9H), 6.97 (s,
1H), 2.83 (s, 6H). Anal. Calcd for C22H16O: C, 89.16; H, 5.44.
Found: C, 89.21; H, 5.30.
Th er m olysis of 11a in P h en yla cetylen e. A mixture of
11a (0.3 g, 1.4 mmol) and phenylacetylene (1 mL) in toluene
(15 mL) was refluxed 28 h. After the mixture was cooled, the
orange crystals formed were filtered to give 3,4-dimethyl-10-
phenyl-7H-benzo[de]pyrazolo[5,1-a]isoquinoline-7-one (69b, 0.35
g, 79%, mp 244-247 °C): IR (KBr, cm-1) 1699 (CdO, s); NMR
(CDCl3, δ) 8.54-7.20 (m, 9H), 6.98 (s, 1H), 2.90 (d, 6H); m/e
calcd for C22H16N2O 324.12626, obsd 324.12679. Anal. Calcd
for C22H16N2O: C, 81.46; H, 4.97; N, 8.64. Found: C, 81.15;
H, 5.03; N, 8.65.
for
C20H22O 278.16706, obsd 278.16770. Anal. Calcd for
C20H22O: C, 86.29; H, 7.96. Found: C, 86.45; H, 8.02. Further
elution resulted in recovery of 11a (80 mg, 15%) as identified
by comparison with an authentic sample.
P h otolysis of 11a in Ben zen e. A benzene (225 mL)
solution of 11a (1.0 g, 4.5 mmol) was irradiated 3 h. The
benzene was removed under vacuum and the residue chro-
matographed on silica gel (benzene). Three compounds were
isolated:
(1) 5,6-Dimethyl-2-phenylacenaphthenone (36, 0.25 g, 20%,
mp 142-143 °C) which sublimes as a light yellow solid: IR
(KBr, cm-1) 1715 (CdO, s); NMR (CDCl3, δ) 7.67 (d of d, 2H),
7.38-7.00 (m, 7H), 4.83 (s, 1H), 3.00 (d, 6H); m/e calcd for
Th er m olysis of 11a in Dim eth yl Acetylen ed ica r boxy-
la te. 2-Diazoacenaphthenone 11a (0.3 g, 1.4 mmol) was
dissolved in toluene (15 mL) containing dimethyl acetylene-
dicarboxylate (1 mL) and the mixture was refluxed 24 h. Upon
concentrating the solution to a small volume, orange crystals
formed which, after filtration, were identified as dimethyl 3,4-
dimethyl-7-oxo-7H-benzo[de]pyrazolo[5,1-a]isoquinoline-10,11-
dicarboxylate (69g, 0.49 g, 100%, mp 240-241 °C): IR (KBr,
cm-1) 1745, 1732, 1712 (CdO, s), 1237, 1218 (C-O-C, s); NMR
(CDCl3, δ) 8.49 (d of d, 2H), 7.54-7.15 (m, 2H), 4.03 (s, 6H),
C
20H16O 272.12010, obsd 272.12081. Anal. Calcd for C20H16O:
C, 88.20; H, 5.92. Found: C, 88.08; H. 6.08. (2) (E)-cis-5,6-
Dimethylspiro[acenaphthene-1,7′-[2,4]norcaradien]-2-one (35,
0.24 g, 20%, mp 165-167 °C) as a light yellow solid: IR (KBr,
cm-1) 1688 (CdO, s); NMR (CDCl3, δ) 7.94-7.00 (m, 4H), 6.90-
6.00 (m, 4H), 3.26 (t, 2H), 2.90 (d, 6H); m/e calcd for C20H16
O
272.1201077, obsd 272.1208065. (3) cis-7a,11a-Dihydro-3,4-
dimethylacenaphtho[1,2-b]benzo[d]furan (37, 0.47 g, 40%, mp
181-183 °C) as light orange crystals when recrystallized from
benzene: IR (KBr, cm-1) 1628 (C ) C, s), no carbonyl; NMR
(CDCl3, δ) 8.74-7.36 (m, 5H), 7.06-6.20 (m, 2H), 6.00-5.53
2.92 (d, 6H); m/e calcd for
C20H16N2O5 364.10591, obsd
364.10658. Anal. Calcd for C20H16N2O5: C, 65.93; H, 4.43; N,
7.69. Found: C, 65.91; H, 4.60; N, 7.64.
(m, 1H), 3.17 (d, 2H), 2.98 (s, 6H); m/e calcd for C20H16
O
Th er m olysis of 11a in Meth yl Acr yla te. A toluene (15
mL) solution of 11a (0.4 g, 1.8 mmol) and methyl acrylate (1
mL) was refluxed overnight. Removal of the solvent under
vacuum produced a light orange solid which was chromato-
graphed on silica gel (benzene).
272.12010, obsd 272.12081. Anal. Calcd for C20H16O: C, 88.20;
H, 5.92. Found: C, 88.05; H, 6.15.
Norcaradiene 35 is highly unstable and must be stored at
low temperature. The norcaradiene (35) was isomerized quan-
titatively to 36 upon refluxing in xylene for 4 h. The product
(36) was isolated upon cooling and evaporating the solution,
chromatography of the residue on silica gel (CH2Cl2), and
recrystallization from benzene.
The first product obtained was methyl (E)-5,6-dimethyl-2-
oxospiro[acenaphthylene-1(2H),1′-cyclopropane]-2′-carboxy-
late (73c, 0.26 g, 50%, mp 163-164 °C) as off-white needles
when recrystallized from toluene/petroleum ether (1:1): IR
(KBr, cm-1) 1730, 1700 (CdO, s), 1207, 1177 (C-O-C, s); NMR
(CDCl3, δ) 7.94-7.10 (m, 4H), 3.67 (s, 3H), 2.85 (d, 6H), 2.85-
2.57, 2.33-1.83 (m, 3H); m/e calcd for C18H16O3 280.10994, obsd
P h otolysis of 11a in Aceton itr ile. A solution of 11a (0.51
g, 2.3 mmol) in CH3CN (225 mL) was irradiated 3 h. Following
removal of the CH3CN at reduced pressures, the residue was
chromatographed (silica gel, benzene) to yield 3,4,8-trimeth-
ylacenaphth[1,2-d]oxazole (41, 0.28 g, 52%, mp 195-196 °C)
as yellow crystals after sublimation: NMR (CDCl3, δ) 7.77-
280.11090. Anal. Calcd for
Found: C, 77.28; H, 5.90.
C18H16O3: C, 77.12; H, 5.76.
Further elution with CHCl3 yielded methyl (Z)-5,6-dimethyl-
2-oxospiro[acenaphthylene-1(2H),1′-cyclopropane]-2′-carboxy-
late (74c, 0.2 g, 39%, mp 145.5-146.5 °C) which was recrys-
tallized from toluene/petroleum ether (1:1) to give off-white
needles: IR (KBr, cm-1) 1745, 1710 (CdO, s), 1210, 1179 (C-
O-C, s); NMR (CDCl3, δ) 7.27 (d of d, 2H), 7.27 (d of d, 2H),
3.74 (s, 3H), 2.80 (d, 6H), 2.80-2.27, 1.98-1.67 (m, 3H); m/e
calcd for C18H16O3 280.10994, obsd 280.11090. Anal. Calcd for
C18H16O3: C, 77.12; H, 5.76. Found: C, 77.06; H, 5.79.
7.13 (m, 4H), 2.82 (s, 6H), 2.61 (s, 3H); m/e calcd for C16H13
-
NO 235.09971, obsd 235.10033. Anal. Calcd for C16H13NO: C,
81.68; H, 5.57; N, 5.95. Found: C, 81.22; H, 5.74; N, 5.83.
Th er m a l Decom p osition of 11a . Finely powdered 11a (0.3
g, 1.4 mmol) was placed in a scoop fitted in an inverted
Erlenmeyer flask attached to the top of an insulated quartz
pyrolysis tube (43 × 2.5 cm) in which the top one-third was
packed with glass wool. At the bottom of the pyrolysis tube
was a receiving flask cooled to -78 °C attached to a vacuum
system. The pyrolysis equipment was evacuated (0.15 mm Hg)
and heated externally to ∼450 °C.
When a solution of 11a (0.1 g, 0.45 mmol) in methyl acrylate
(10 mL) was stirred at room temperature for 24 h, no 11a
7132 J . Org. Chem., Vol. 69, No. 21, 2004

2-Diazo-5,6- and -3,8-disubstituted Acenaphthenones
remained. Purification and chromatography of the crude
product led to isolation of 73c and 74c in excellent yields.
thalene, quinones 19b-d and 20, p-tosylhydrazones 17b-d
and 18, diazoacenaphthenones 11b-d and 12; (3) reactions
of 11b and 12 in various environments; and (4) preparation
of 47a ,b, 48a ,b, 49a , 50a ,b, 51a ,b, 53a ,b, 54, 55, 60, 61a ,b,
63, 64, 69h -j, 70b, 3,3′-dimethylbiphenyl, and 8,8′-di(m-tolyl)-
1,1′-dinaphthyl. This material is available free of charge via
the Internet at http://pubs.acs.org.
Ack n ow led gm en t. Eastman Kodak, the National
Institutes of Health, and the National Science Founda-
tion are thanked for support of this research.
Su p p or tin g In for m a tion Ava ila ble: Procedures involv-
ing (1) methods and materials; (2) syntheses of 1,8-diphenyl-
naphthalene, 1,8-di(m-tolyl)naphthalene, 2,7-dimethoxynaph-
J O040175H
J . Org. Chem, Vol. 69, No. 21, 2004 7133