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Free-Radical SH2 Diplacement in the Triazene System.

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spectrum (in THF at -55°C) shows, besides the two
doublets of the two AB systems of the five-ring protons at
?=3.15 (H-2, H-3) and 3.65 (H-I, H-4) (J=4.0Hz), a1so.a
multiplet centered at T =2.70 for the three six-ring protons.
Hydrolysis of (5), which regenerates ( 4 ) , also confirms
the theoretical expectation^[^], according to which position
1 or 4 should have a high electron density. In agreement
therewith, reaction of (5) with benzophenone leads to
thermally stable 1-(diphenylmethylene)cyclopent[cd]indene ( 9 ) [yellowish-orange prisms, m.p. 125°C (dec); UV
spectrum (in n-hexane), h,,,=255 (4.34), 310 (4.33 352
(4.28) nm (log E); NMR spectrum (in CCl,), '5 =2.62 (6 H/s),
2.66 (3 H/s), 2.70-3.70 (7 H/m)], which can also be obtained from ( 8 ~ ) and
" ~ phenylmagnesium
~
bromide after subsequent dehydration and by dehydrogenation with 2,3-dichloro-5,6-dicyano-p-benzoquinone
(DDQ) in 30% yield.
Like the formation of (4) from (8b), the hydrolysis of the
Li salt of ( 5 ) which leads to ( 4 ) shows that ( 4 ) is energetically favored over (3). Correspondingly, a higher total n
electron energy was found by SCF-CI
calculation^^'^^
for the 1H-tautomer ( 4 ) than for the 2aH-tautomer (3)[ls1.
The unexpectedly low acidity of ( 4 ) , comparable with that
of indene, probably represents a considerable difference
of 1H-cyclopent[cd]indene ( 4 ) from its 2aH-tautomer
(3) for which a pK value of 11 has been calculated[61.This
can probably be ascribed to a considerably lower gain of
energy on conversion of the fulvenoid tricycle ( 4 ) into its
anion (S) than in the corresponding deprotonation of the
indene-like hydrocarbon. Also, the correlation obtained
by Streitwieser's method between acidity and the n-electron
energy difference of anion and hydrocarbon leads to an
appreciably lower pK value for ( 4 ) than for (3). Attempts
to convert the hydrocarbon ( 4 ) into its cation and radical
are in progress.
[I21 The mean errors in the extinctions, referred to 2092, in the UV
spectrum of the Li salt of (5) amount to 5-10%. For UV measurements a solution containing methyllithium was used whose low transmittance below 330nm did not permit the absorption curve to be
observed at lower wavelengths.
[13] Prepared from ( 8 b ) and thionyl chloride
[I41 R . Zakradnik, personal communication.
[I51 Simpler HMO calculations for ( 3 ) and (4) led to the same result
( A . Streitwieser, J . I . Bmuman, and C. A . Coulson: Supplement Tables
of Molecular Orbital Calculations. Pergamon Press, Oxford 1965; E.
Heilbronner and P . A . Straub: HMO Huckel Molecular Orbitals.
Springer-Verlag, Berlin- Heidelberg- New York 1966).
Free-Radical S,2y Diplacement in the
Triazene System1*"]
By Jochen Hollaender and Wilhelm P . Neumannl*]
The action of stannyl radicals R3Sn' on 1-aryl-3-alkyltriazenes (I a) -(I c) resulted in replacement of the
arylazo group on N3 by the stannyl group [eq. (1) and
Table]. This S,2a reaction corresponds to known types
of displacement by free radicald2 - 51.
1
2
3
Ar-N=N-NR'R'
-+
Ar.
1
+
Nz
+
R3Sn-NR'R2
+ R,SnH
R3Sn-
iA r - H
i+H,SnH
RsSnz
+
(1)
HNR'R'
Received: July 12, 1971 [Z 472 IE]
German version: Angew. Chem. 83,802 (1971)
Surprisingly, 1,3-displacement (S,2y) also occurs and predominates or becomes almost the only reaction when at
least one of the groups R' and RZ on N3 forms a stable
[I] K . Hafner and H . Sckaum, Angew. Chem. 75, 90 (1963); Angew.
Chem. internat. Edit. 2, 95 (1963); K Boekelheide and C . D. Smith, J.
Amer. Chem. SOC.88, 3950 (1966); K . Hafner and W Rieper, Angew.
Chem. 82, 218 (1970); Angew. Chem. internat. Edit. 9, 248 (1970).
[2] H . Rapoport and G . Smolinsky, J. Amer. Chem. SOC.82,934 (1960);
R . Kuhn and D. Rewicki, Liebigs Ann. Chem. 706, 250 (1967).
[3] R . J . Windgassen, W H . Saunders, and !I Boekelkeide, J. Amer.
Chem. SOC.81, 1459 (1959).
[4] R . Zakradnik, J . Mickl, and J . Kouteckj, Collect. Czechoslov.
Chem. Commun. 29, 1932 (1964); R . Zakradnik and J . Mickl, ibid. 30,
3529 (1965); P . Hockmann, R . Zahradnik, and K Krasnicka, ibid. 33,
3478 (1968); R . Zahradnik, Angew. Chem. 77, 1097 (1965); Angew.
Chem. internai. Edit. 4, 1039 (1965).
[S] F. Gerson, E. Heilbronner, N . Loop, and H . Zimmermann, Helv.
Chim. Acta 46, 1940 (1963).
[6] A . Streitwieser, Jr., Tetrahedron Lett. 1960, 23.
[7] H . Rapoport and J . Z . Pasky, J. Amer. Chem. SOC.78,3788 (1956);
H . Rapoport and G . Smotinsky, ibid. 82, 1171 (1960); B. L . McDowetl,
G . Smolinsky, and H . Rapoport, ibid. 84, 3531 (1962).
[S] (7) was obtained by M . 0. Forster's method (J. Chem. SOC.107,
260 (1915)) from 3,4-dihydro-4-(hydroxyimino)-5(2aH)-acenaphthenone [7] and chloramine as pale yellow, small, light-sensitive rods, m. p.
61 "C, in 75 % yield.
191 All the compounds described gave correct analyses.
[lo] A . Pullmann, B. Pullmann, E. D. Bergmann, G. Bertkier, I: Hirskberg, and I: Sprinzak, Bull. SOC.Chim. France 18, 702 (1951).
[I 1J Prepared from 4-amino-5-acenaphthenol hydrochloride ( H .
Rapoport, 7: P . King, and J . B. Lauigne, J. Amer. Chem. SOC.73, 2718
(1951)) and n-butyl nitrite; on recrystallization from light petroleum
in presence of active charcoal the 4-diazo-5(4H)-acenaphthenone first
obtained in this synthesis was dehydrogenated to the acenaphthylene
derivative; pale yellow needles, m.p. 134°C; yield 56%.
752
A r N ( S n R 3 ) -NH-NR'R'
(4)
LR3Sn*
iR1-H
-
+ n3nn2
R2
Ar
(3)
free radical, i. e. when the dissociation energy of its bond
to N3 is lowered. Examples include R' =benzyl, triphenylmethyl, or trialkylstannyl [see (Id)-(I i), eq. (2), and
Table]. The stannyl radical attacks at N'. The intermediate
[*] DipLChem. J. Hollaender [I] and Prof. Dr. W. P. Neumann
Lehrstuhl fur Organische Chemie der Universitat
46 Dortmund, August-Schmidt-Strasse 6 (Germany)
[**I This work was supported by the Fonds der Chemischen Industrie.
Angew. Chem. internat. Edit. 1 Vol. I0 (1971) 1 NO. I0
radical (2) rapidly undergoes the reverse reaction ( k - ') or
elimination ( k 2 )to give pentacoordinated[61N-stannyltriazene (3). In any case, no stabilization products ( 4 ) , which
could be formed from (2) through H-abstraction from the
powerful radical scavenger present (organotin hydride),
were detected. Attack on NZwould lead to the intermediate
It may be assumed that attack of the 7~ system of the azo
group also occurs as a competing reaction in the case of
eq. (1)but remains very much in the background owing to
a lack of readily replaceable groups R. This behavior of
the N-N group would correspond to that of internal
c=C groups"'.
The reactions depicted in eq. (1) and eq. (2) are greatly
accelerated, or in some cases even made possible, at 80°C
by free radicals from azoisobutyronitrile or at 28°C by
UV irradiation (h,,, 254 nm).
R'TR~
N - SnR3
I
Ar-N.
(5)
radical ( 5 ) , but no reaction products of this species were
observed.
Initial attack by the stannyl radical on N3 with subsequent
1,l-displacement of R' (SH2a)can also be ruled out since
The triazene system behaves here as a triaza analog of the
allyl system and it is likely that the S,2y reaction described
above is possible with all allyl analogs, as we have actually
observed with the allyl system itself[*].A number of allyl
displacement reactions proceed by the same mechanistic
route['', while various other free radical reactions''']
correspond to an SH2pmechanism.
Received: July 16,1971 [Z 478 I€]
German version: Angew. Chem. 83,850 (1971)
Table. S,2u and S,2y reactions of aryltriazenes (1) (0.4 M in cumene
at 80°C) with (C,H,),SnH. molar ratio 1 :4. Results after six hours'
reaction. Catalyst : azoisobutyronitrile.
(1)
Ar
R'
R2
Yield (mol.-%)
based on
reacted (I)
Ar-H
R1-H
eq. (1)
eq. (2)
100
100
100
13
10
7
7 [c]
2
61
0
0
0
a7
90
al;{7,
93
98 [a1
re1
An a-Lactam Derived from 2-Adamantylaminet**I
By Erach R . Talaty,James P. Madden, and Louis H . Stekol"']
Several a-lactams having a tertiary-alkyl group attached
to the nitrogen atom are known['! Attempts to prepare
a-lactams with other types of alkyl substituents on nitrogen
have been made, but such a-lactams have been reported
to be either not formed or too reactive to be isolated['!
We now report the isolation of an a-lactam, 1-(2-adaman-
[a] R'-H is in equilibrium with ( I f ) or ( I h ) respectively
[b] At 60°C without catalyst.
[c] Benzene (Ar-H) is formed here from spontaneous decomposition
of (IS).
[d] In toluene at 20°C without catalyst.
[el NH, is formed. A quantitative determination has yet to be performed.
benzylaniline, diphenylbenzylamine, or N-benzylimidazole
gives no toluene under the above conditions. Moreover,
such an attack is unlikely in the case of the triphenylmethyl
derivative ( I g) for steric reasons.
[l] J . Hollaender, Dissertation, Universitat Dortmund 1971.
[2] W P. Neumann and Hch. Lind, Chem. Ber. 101,2837 (1968).
[3] K . Riibsnmen, W P. Neumann, Ra. Sommer, and U . Frommer,
Chem. Ber. 102, 1290 (1969), and earlier literature cited therein.
[4] W P. Neumann, Hch. Lind, and G. Alester, Chem. Ber. 101, 2845
(1968).
[S] For a review, see A . G. Dacies and B. P. Roberts, Nature Phys.
Science 299, 221 (1971).
[6] F. E. Brinckmann, H . S . Haiss, and R . A . Robb, Inorg. Chem. 4,935
(1965); see also ref. [I].
[7] R . Sommer and H . G. Kuicila, J. Org. Chem. 33, 802 (1968); H.-J.
Albert, W P. Neumann, W. Kaiser, and H:P. Ritter, Chem. Ber. 103,
1372 (1970), and further literature cited therein.
[S] H:J. Alberr, W. P . Neumann, and H.-P. Rirrer, Liebigs Ann. Chem.
737, 152 (1970).
191 R . K h . Freidlina, Advan. Free Radical Chem. I , 211 (1965), and
further literature cited therein.
[lo] J . K . Kochi and P. J . Krusic, J. Amer. Chem. SOC.91,3944 (1969),
and further literature cited therein.
Angew. Chem. internat. Edit.j Vol. 10 (1971) / No. 10
R1-CHR2-CO-R3
( a ) , R 1 = I-adamantyl,
( b ) . R' = I-adamantyl,
(c), R' = 1-adamantyl,
(1)
R 2 = H, R3 = C1
R2 = Br, R3 = CI
R2 = Br, R3 = NH-2-adamantyl
tyl)-3-(l-adamantyl)aziridin-2-one( 2 a ) , which has a secondary-alkyl group attached to position 1, and is remarkably stable. Compounds of this type could also have potential
applications in medicinal chemistry, since l-adamantylamine and its derivatives have been reported to have antiviral activityf31.
The acid chloride ( l a ) was treated with bromine in boiling
carbon tetrachloride until conversion into ( I b ) was
complete, and the crude reaction mixture was allowed to
react with 2-adamantylamine to afford, in 71 % over-all
yield, the bromo-amide ( I c ) , m. p. 237.5-24O.O"C (decamp.) [NMR (CDCl,, 60MHz, &value in ppm relative
to TMS): 6.60 (N-H/broad d, J = 8 Hz), 4.08 (1 H/s),
4.08 (1 H/broad d, J = 8 Hz), 2.26-1.44 (29 H/m); mass
spectrum: m/e 407/405 (M+), 326 (M'-Br)].
Reaction of
(Ic) with potassium tert-butoxide in ether at 0°C effected
ring closure to the desired a-lactam (2a), m.p. ~ 2 2 5 ° C
(decomp.). However, in contrast with the preparation of
a-lactams such as (Zb)[41, where the ring-closure could be
[*I
Prof. Dr. E. R. Talaty, J. P. Madden, and L. H. Stekoll
Department of Chemistry, Wichita State University,
Wichita, Kansas 67208 (USA)
This work wassupported by the Wichita State University Research
Committee.
[**I
753
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