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anti-[4 + 4]-Dicyclopentadiene.

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NMR (CDCI,): 6 = 2.48, 2.58 (each CH,)]; the nitrile group
in (5) can be readily cleaved by treatment with potassium hydroxide in ethanol13].(4) even adds to benzene (12 h reflux)
with formation of 2-methyl-3-phenyl-3a,7a-dihydroindole-lcarbonitrile (6) as the sole reaction product [yield 80% m. p.
93°C; IR (KBr): uc N=2219, vc c=1662 cm-'; 'H-NMR
(CDCI3): 6=4.18 (broad d, 35H.3a,H.7a=14.5Hz, H-7a), 4.90
(dd, 3J~.3,,~.7a)=14.5
HZ, ,J~.7,~.3*=4
HZ, H-3a), 5.50, 6.18
(each m, H-4, H-7), 5.85 (m, H-5/H-6)lr4].
As a 1,3-diene, (6) reacts with l-phenyl-1,3,4-triazoline2,5-dione (dichloromethane, 20 "C) in a [4 + 2]-cycloaddition
to give (7) (m.p. 268 "C) in 86% yield. On heating with 2,3dichloro-5,6-dicyano-p-benzoquinone
in benzene (6) is dehydrogenated to 2-methyl-3-phenylindole-I -carbonitrile (yield
70%; 89 "C); 'H-NMR (CDCl3): 612.54 (CH3), 7.0-7.6
(aromatic H).
The ketenimine rearrangement of (4) involving a 1,2-methy1 shift['], which is observed alongside OH insertion (ratio
25:75) in the photochemical decomposition of (2) in methanol, does not occur in the presence of the dipolarophile.
[2] H Bonnemunn. Angew. Chem. 82, 699 (1970); Angew. Chem. Int. Ed. Engl.
Y. 736 (1970).
131 E. 0. Sherman, P. R. Schreiner, J. Chem. SOC.Chem Commun. IY78.223; J.
F. Nixon. B. J. Wilkins, J. Organomet. Chem. 80, 129 (1974): J. W. Byrne. H.
0. Blaser. J. A. Osborn, J. Am. Chem. SOC 97, 3871 (1975): T. H. Tulip,J. A.
fbers. ibid 101,4201 (1979); E. L. Muerrerties, J . R Bleeke. Acc. Chem. Res.
12, 324 (1979).
[4] G. Curfuran. A. Scriuanri. B. Longalo. F. Morandini, J. Organomet. Chem
172. 91 (1979).
151 L. Abrs. A. Sen. J. Halpern, J. Am. Chem. SOC.100, 2915 (1978).
[6] P W. Jolly, G. Wilket The Organic Chemistly of Nickel. Vol. I and 11. Academic Press, New York 1974 and 1975. respectively.
Pronounced 1,3-Dipolar Cycloaddition Behavior
of an a-Cyanimino Carbene['*'
By Daniel Danion, Bernhard Arnold, and Manfred Regitzl''
Open-chain a-oxocarbenes such as benzoylmethyl or acetylmethyl carbene readily undergo Wolff rearrangement to
ketenes, and only reluctantly undergo 1,3-dipolar cycloadditions-for instance, with acetonitrile-the yields of which
are minimal and can be increased to a maximum of 17%only
by addition of copper or copper compounds[''. By way of
contrast the a-cyanimino carbene (4) shows a pronounced
readiness to undergo such cycloadditions.
A suitable starting material for the generation of (4) is the
triazole-1-carbonitrile (2), obtained in 90% yield by reaction
of the methylenephosphorane (1) with cyanazide in dichloromethane/acetonitrile at 20 "C with concomitant formation of
triphenylphosphane oxide [m. p. 140 "C; IR (KBr):
UC-N = 2260 cm- I; 'H-NMR (CDC13): 6 = 2.65 (CH,)][']. In
spite of the pronounced tendency of 1,2,3-triazole-l-carbonitrile to undergo ring-opening''], no a-diazoimine (3) can be
detected alongside (2) in the equilibrium (no C N2 absorp-
Received: August 22. 1980 [ Z 671 IE]
German version: Angew. Chem 93. I18 (1981)
CAS Registry numbers:
(I), 76068-72-9; (2). 76068-73-0: (3). 76068-74-1; (3). 76068-75-2 cis-l6). 7606876-3: (7). 76068-77-4; cyanazide, 764-05-6; 1 -phenyl- 1,3,4-triazoline-2,5-dione.
4233-33-4; 2-methyl-3-phenylindole-1
-carbonitrile, 76068-78-5
[ I ] R. Huisgen, G. Binsch, L. Ghosez. Chem. Ber. Y7. 2228 (1964).
[2] For the method see B. Arnold. M. Regitr, Tetrahedron Lett. IY80. 909.
131 This leads to formation of 2.5-dimethyl4-phenylimidazole:
A. Novel/&.A. de
Santis. Tetrahedron Lett. 1967. 265.
[4] It cannot be totally ruled out that (4) forms [2+ 11-cycloadducts with the dipolarophiles. which subsequently isomerize to (5) and (6).respectively.
[ 5 ] Cf. B. Arnold. M . Regitr, Angew. Chem. 91, 337 (1979): Angew. Chem. Int.
Ed. Engl. 18, 320 ( I 979).
Ph
A
CH3
Ph
d
- Nz
N-CN
-s
N-CN
(41
tion in the IR spectrum (CDC13) at 20 "C); nevertheless, (4) is
presumably formed under thermal conditions via a small
equilibrium concentration of (3).
When a solution of (2) in acetonitrile is heated under reflux for 10 h, 2,5-dimethyl-4-phenylimidazole-l
-carbonitrile
(5) is formed by [3 + 21-cycloaddition of (4) to the solvent
[yield 75%; m.p. 1 5 8 ° C IR (KBr): uc -N=2222 cm-'; 'HI*]Prof. Dr. M. Regitz, Dr. B. Arnold
Fachbereich Chemie der Universitat
Paul-Ehrlich-Strasse, D-6750 Kaiserslautern (Germany)
Carbenes. Part 24. This work was supported by the Fonds der Chemischen
1ndustrie.-Part 23: M. Regnirz, H. Eckes. Tetrahedron 37 (1981). in press.
Angew. Chem. Int. Ed. Engl. 20 (1981) No. 1
0
unri-[4+ 41-Dicyclopentadiene
By Wolfram Grimme, Lothar Schumachers, Rolf Gleiter,
and Klaus Gubernatorc'l
The [4 + 4]cycloadducts of conjugated carbocycles are
more strained than their [2 + 21 and [2 + 41 structural isomers
and are not directly accessible by thermal, photochemical or
metal-catalyzed routes. Their high energy content and the interaction between the central a-bonds, and the flanking double bonds, make this class of compounds of interest for ther1') Dr. W. Grimme"', Dip1.-Chem. L. Schumachers
Institut fur Organische Chemie der Universitat
Greinstrasse 4, D-5000 Koln 41 (Germany)
Dr. D. Danion
Groupe de Recherches de Physicochimie Structurale
Faculte des Sciences de I'Universrte, B.P. 25 A,
F-35042 Rennes (France)
[**I
CH3
['I
Prof. Dr. R. Gleiter, DipLChem. K. Gubernator
Organisch-chemisches Institut der Universitat
Im Neuenheimer Feld 270. D-6900 Heidelberg 1 (Germany)
Author to whom correspondence should be addressed.
0 Verlag Chemie, GmbH, 6940 Weinheim, 1981
0570-0833/33/sl/0~~1-0l13 $ 02.5010
113
ma1 studies and photoelectron spectroscopic investigations.
The syn stereoisomer of the title compound could be prepared['] by partial ring opening of an appropriate cage compound in the key step. However, in the synthesis of the anti[4 + 41-cyclodimerof cyclopentadiene (7) we used an alternative procedure: ring contraction of its readily available tropone [4 + 61-cycloadduct
(21
(3)
( l a ) , R' R~ = 0
( J b ) , R' = H, R 2 = OH
( J r ) , R' = H , R 2 = OSOzCH3
c1
Table 1. Physical data for compounds (2) to (7). 'H-NMR spectra were recorded
at 90 MHz in CC1, [(3) in CDCI,]; He(I)-PE spectra were recorded on a PS 18
specfrometer (Perkin-Elmer).
(Z), M.p=37'C; 'H-NMR: 6=6.02 (m. 2H). 5.45 (m, 2H). 2.4 (m, 6H).
1.8 (m, 3H). 1.3 (m, 3H); "C-NMR: 6 = 135.08, 128.48, 47.54, 38.02, 34.74.
30.50, 27.13
(31, 'H-NMR: 6=6.07 (m. 4H). 5.96 (m, 2H), 2.77 (m. 2H), 2.43 (m, 2H). 1.65
(AB, A u = 100 Hz, J = 12.5 Hz, part A split into triplets). 1.45 (AB, Av=51 Hz,
J = 10.5 Hz, part B split into triplets): "C-NMR: 6 = 140.51, 133.44, 126.30,
47.63,35.49.34.42.2536; MS:m/e= 158(Mt),92(M+ -C5Ho, l00%).91 (C,H:,
98%), 66 (CsHd); UV: Am,,=241 ( ~ = 5 8 0 0 )sh, 250 (7100). 259 (7500). 269 nm
(4800); PE: 8.25, 8.75, 10.3. 10.7 eV
(4). 'H-NMR: 6=6.02 (m, 2H), 5.93 (s, 2H). 3.23 (s, 2H), 2.33 (m. 2H). 1.75 (m.
2H), 1.73 (AB, Au= 96 Hz. J = 10.5 Hz, part B further split), 1.47 (m, 2H); MS:
m / e = 158 ( M + ) ,92 ( M i -CsH6, 85%), 91 (C,H ;, 100%). 66 ( C S H i )
(5). dissociation temp.=240"C; MS: m/e=404 (M+).
378 ( M +-C,H,), 322
( M + -2CO-C2H2), 216 (C,H,CI:), 132 (C,oH T2). 106 (CXHT"), 91 (C,H:), 78
) 278 (1400), 435
(CgH6t). 66 (CrH:); UV (acetonitrile) A,,,=235 ( ~ = 3 0 0 0 sh.
nm (200)
(6). M.p.=133"C; ' H - N M R 6=5.94 (s, 2H), 2.97 (s, 2H), 2.87 (m. 2H), 2.48
(m,2H),2.0-1.0(rn,6H); MSm/e=348(M+),216(CaH2C1;), 132(CIuH72),
106 (C8H:,), 91 (C,H;). 78 ( c , ~ ; ) , 66 (c~H;, 100%); UV (dioxane):
A,.,=272 ( ~ = 2 7 0 0 )sh, 287 (4OOO) sh, 297 (4800). 310 (4100) sh. 327 nm (1.600)
sh
(7). M.p.=135"C in fused glass capilliary tube; 'H-NMR: 6=6.08 (s, 4H),
2.12 (m. 4H). 1.83 (AB, Av=22.3 Hz, J = 9 . 0 Hz, part B further split); "C-NMR:
6 = 134.81 (C-3,4,7,8), 47.36 (C-9,10), 36.56 (C-1,2,5,6); MS: m / e = 132 ( M + ,
3%), 66 (CsH;, 100%);UV (hexane): A,.,=211
nm (~=4500);PE: 8.2, 9.8 eV
The syn alcohol (lb), obtained by reduction of ( l a ) by diisobutylalane in dichloromethane, is transformed by treatment with methanesulfonyl chloride in etherhiethylamine
into the ester (lc) (m.p. = 99 " C )in 82% yield; ( l c ) is then reduced to the hydrocarbon (2) (44%,for physical data see Table
1) by sodium in liquid NH3/THF. Reaction of (2) with dichlorodicyano-p-benzoquinonein boiling C C 4gives (3) (55%),
which in ether solution cyclizes to the four-membered ring
compound (4) in 72% yield when photolyzed at 0 "C (Hanau
Hg low-pressure lamp NK 6/20) through quartz. The assignment of the exo configuration to the photoproduct (4) follows from the absence of coupling between the aliphatic pro-
114
0 Verlag Chemie, GmbH, 6940 Weinheim, 1981
tons of the four-membered ring and the bridgehead protons,
and from the small change in the chemical shift difference
(As= 1.06 ppm) between the methylene protons of the norbornene part in going from (3) to (4). The cyclobutene ring
in (4) is degraded using the method of Warrener et al.C3J,by
first forming the cycloadduct (5) (74%)[41with o-chloranil in
CCl, (70 "C). Irradiation of a solution of (5) in dichloromethane with an incandescent lamp (Osram Bellaphot, 400 W)
through Solidex gives the bis decarbonylated product (6)
(69%). Compound (6) dissociates into a mixture of anti-tricyclo[4.2.1.I 2.5]deca-3,7-diene(7) and tetrachlorobenzene when
photolyzed under similar conditions using a Hg high-pressure lamp (Philips HPK 125)I5].The title compound (7) is
separated from tetrachlorobenzene by column chromatography (silica gel, pentane) and from residual eluent by gas
chromatography (10% DEGS, 0.5 m, 30°C); it forms colorless crystals (38%) which have a high vapor pressure and a
penetrating smell.
The PE spectrum of (7) is characterized by two broad
bands of equal intensity at 8.2 and 9.8 e V the large splitting
(Alp = 1.6 eV) of the vertical n-ionization potential is caused
by the strong interaction between the double bonds and the
central single
This same electronic effect also
manifests itself in the UV spectrum of (7), the absorption
maximum of which occurs at h=211 nm (~=4500);an unusually long wavelength for an unconjugated dienelbb1.
The [4 + 41-dicyclopentadiene (7) dissociates to the monomer at 180 "C by a [4 + 4]retrocyclization, which according
to the rules of conservation of orbital symmetry[71must proceed via the diradical (8).Its intermediary is indeed indicated
by small amounts of endo-[2+ 41-dicyclopentadiene (9) and
anti-cis-[2+ 21-dicyclopentadiene ( I f f ) , products of recyclization, which under the reaction conditions also dissociate to
the m ~ n o m e r [ ~ , ' ~ ] .
z-g
(81
(7)
-
2
191
\
'
2
0
&*)
The thermal behaviour of anti-[4 + 41-dicyclopentadiene
differs significantly from that of the syn stereoisomer['l,
which at 58 "C forms syn-cis-[2+ 21-dicyclopentadiene via a
synchronous Cope rearrangement without giving the products of a radical process.
Received: August 14, 1980 [Z 657 IE]
German version: Angew. Chem. 93, 98 (1980)
CAS Registry numbers:
(Ib). 68926-88-5, (Ic). 75993-66-7; (2). 75993-67-8; (3), 76024-05-0; (4). 7599368-9: (5). 75993-69-0; (6). 75993-70-3; (7), 76024-06-1; (9). 1755-01-7; (lo),
76024-07-2; (11). 35522-50-0, (12). 75993-714,o-chloranil, 2435-53-2
Ill C. W. Doecke, G. Klein, L. A. Paquetie, J . Am. Chem. SOC.100, 1596 (1978):
101,7599 (1979).
121 a) R. C. Cookson, B. V. Drake, J. Hudec, A. Morrison, Chem. Commun
1966, 15; S. Itd, Y. Fujise, T Okuda, Y. Inoue, Bull. Chem. SOC.Jpn. 39,
1351 (1966). b) S. Itd, I . Iioh, Y. Fujise, T. Nakatsu, C. A. Senkler. P. v. R.
Schleyer, ibid. 51, 2379 (1978)
131 E. E Nunn, W. S. Wilson, R. N . Warrener, Tetrahedron Lett. 1972, 175.
141 In addition to (5) a 2: 1 adduct. caused by a second addition to the norbornene double bond. is formed.
0570-0833/81/0101-0114
$
. 02.50/0
Angew. Chem. Int. Ed. Engl. 20 (1981) No. 1
151 In the analogous degradation of the photoketone (il) (M.p.=3S°C; T. M u kai, Y. Akasaki. T Hagiwara, J. Am. Chem. SOC.94, 675 (1972)) was formed
(i2) (dissociation temp.
the anti-tricycl0[4.2.1.1~~~]deca-3,7-dien-9-one
= 152 'C). W. Mauer, Dissertation, Koln 1978.
Direct comparison of the 'H-NMR data of the anions (5)
with those of the conjugate acids (4). all of which exhibit
bands in a region (6 = 6.5-7.0) normally reserved for meso-
[6] a ) MIND0/3 result [eVI. 8 61 (a,(.rr)); 9.90 (bv(m)); b) CNDO/S-CI result
[nml: 221.4, f=0.000, m*(b,)ea(a,); 210.0.f=0.146, .i*(a,)+m(a,).
[7] R. B. Woodward, R. Hofmann. Angew. Chem. 81, 797 (1969); Angew.
Chem. Int. Ed. Engl. 8, 781 (1969).
[8] G. S Hammond, N . J. Turro, R. S. H. Liu, J. Org. Chem. 28. 3297 (1963).
191 In the thermolysis of anfi-[4 +4]-dicyclopentadienone the corresponding recyclization products of the intermediate radical are formed: U.Klinsmann,
J. Gauthier. K. Schaffner, M. Pasternak, B. Fuchs, Helv. Chim. Acta 55,2643
(1972).
[lo] The kinetic analysis of the dissociation of (71 has been carried out by Prof.
W. R Roth. Universitat Bochum. and will be published separately.
Generation and NMR Spectroscopic Investigation
of Diheteroanthracenide Ions: Stable 4nm Systems[**'
By A. G. Anastassiou, H . S. Kasmai, and M. R. Saadein'']
The three potentially antiaromatic 4n7r systems (la)-(lc)
were recently prepared and analyzed (NMR) in our laboratoriesl'] to reveal, at least in the case of the first-row variants
(1a)I'"l and (lb)"1' , the presence of well-developed molecular
paratropicity. In an effort to assess the possible effect that increased n-frame electronegativity may have on the magnitude and/or nature of this ring current effect we next focussed our attention on a group of direct diheteroatomic relatives of ( l ) ,namely the amide ions (5) and wish to briefly
elaborate on our findings in the area.
B
v
7
5
fi
4
3
t d
Fig. 1.60-MHz 'H-NMR spectrum (A) of the phenoxazene anion (5b) and ( 8 ) of
the N-methyl-9.10-dihydrophenazineanion (50) in liquid ammonia (THF as Internal standard) at ca. 34 "C.
Table 1. "C-NMR data [a] of compounds (2). (3). (46). (4c). ISa)-(5c). The instability of 5.10-dihydrophenazine (4a) in liquid ammonia precludes the recording of a "C-NMR spectrum.
CPd
Chemical Shift [b]
(W Icl
Obt
(4)
(5J
OCt
The desired diheteroanthracenide ions (Sa)-(Sc)
were
prepared as deeply colored, thermally stable solutions''] by
deprotonation of the amines (4a)-(4c) with KNHz in NH3
at ca. - 30 "C. For purposes of direct comparison the 'HNMR spectra of the N-methyl-5,lO-dihydrophenazineanion
(5a) and phenooxazine anion (5b) are reproduced in Figure
1. As expected, the 'H-NMR spectrum of the phenothiazine
anion (Sc) is similarly patterned [6 = 5.7-6.2 (m, 6 H), 6.41
(dt, 2 H)], while that of the diphenylamide ion (3) is markedly different IS = 6.0-6.4 (m, 2 H) and 6.7-7.1 (m, 8 H)]. The
I3C-NMR data of the compounds described are collected in
Table 1.
['I
Prof. Dr A. G. Anastassiou ['I, M. R. Saadein
Department of Chemistry, Syracuse University
Syracuse. New York 13210 (USA)
Prof. Dr. H. S. Kasmai
Department of Chemistry, Shiraz University, Shiraz (Iran)
["I This work was supported by the National Science Foundation.
[ '1 Author to whom correspondence should be addressed.
Angew Chem lnr Ed Engl 20(1981) No. I
(461
(4C)
(2)
(3)
tert C-atoms
quat C-atoms
40.51, 45.15. 45.74, 55 25
44.02, 44.99, 48.31. 57.09
47.00. 50.55, 57.74, 60.35
46.49, 48.47. 53.48, 57.04
46.77, 54.20. 58.92, 59.96
50.63, 53.11, 62.46
43.57, 50.86, 62.00
72.99, 86.62 [d]
80.28, 82.72 [d]
49.27. 89.05 [d]
76.86, 66.64
49.75. 75.66
77.78
91.62
[a] The spectra were recorded at 60 MHz and ca. 30 " C in liquid ammonia containing ca. 10 ' cm' /D,]tetrahydrofuran as standard. [b] S values, referred to the
central signal of the low-field multiplet of [D,]THF (STMS=-67.9). [cl
S = - 36.33 (CH,).
[d] C-9a.
~
merically enriched benzenoid moieties, clearly reveals the
"4n"-7r diheteroanions (5) to be endowed with elements of
molecular paratropicity. Additionally, internal comparison
along these lines between (Sa), (Sb), and ,(5c) appears to
establish the magnitude of the induced ring current to be
largest in the former and smallest in the latterf3].Interestingly, this interpretation gains credence from an analysis of the
13C-NMR data (Table 1) which appears to also offer a reasonable explanation as to why sulfur is less effective than
either oxygen or nitrogen (NMe) in contributing its lone pair
to the development of n delocalization in (5). Specifically,
one notes that whereas the signals of the tertiary carbons of
0 Verlag Chemre, GmbH, 6940 Wernherm, 1981
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115
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