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Simple Bridged cis-Oxa- and cis-Aza-tris--homobenzene Systems; Synthesis and 33 Isomerization.

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vie\\ of the mirror image geometry of the substituents in
the transition state (Fig. 7). The rearrangement obcys first
order kinetics at all temperatures (k31,8 c=5.23 x lo-'?
k,,
,.=ISOX
k,j,O .=2.39x lo-", k 4 8 , h .=3.53x
lo-'). The activation energy E , for the degenerate diaza-Cope
rearrangement is found to be 21.8 kcaljmol. Interestingly, a
value of 23.9kcal/mol is obtained for A G * . which agrees with
that determined by the coalescence method. As expected, the
entropy of activation is strongly negative: AS* = -7.5cal
deg- mol- '
R+NTHR
H
:Z3LZ7
I-is 2. R x c n i i / a t t o t i ( S . S ) - ( 2 ) - ( R , R ) - ( ? ' ) o r ( R . R ) - ~ ~ j ~ ( S . S T) -h(e ~inir
'~.
r o r image in thc triinsition state is s h o w n gray.
The degenerate diaza-Cope rearrangement even appears to
take place in the solid state: crystals of ( - ) - ( 2 n ) lose their
optical rotatory power within 24 h.
Introduction of o, n 7 , or p substituents into the four aromatic
nuclei of ( 2 ) leads to further degenerate diaza-Cope systems.
The compounds studied hitherto confirm the results obtained
with the unsubstituted system ( 2 a ) : only minimal changes
arc found in the activation parameters of ( 2 h ) and ( 2 ~ ) .
In the presence of electron-attracting substituents as in (2ci)( 2 f J avoidance reactions occur which are possibly attributable
to an irreversible cleavage of the weakened ally1 o bond.
The considerable influence of the 3,4 phenyl substituents of
( 2 a ) is underlined by the lack of any tendency of N,N'-dibenzylideneethylenediamine to undergo rearrangement at 210°C.
Recetccd. April 30. 1974 [7 34 I E ]
G e r m a n \erston: Angcw. Cheni. 86.520 11974)
[ I ] M . J . S. Drwar a n d D. H . Lo, J Amer. Chem. Soc 93. 7201 (1971).
\I J . S Lkn~ii.. L. . V d i / o t h i . and U. : X d t l ~ i i \ A ~ i C'liem.
.
Commun. ! 9 ? / .
1373: cf. also R. Ho//nior7t7 and U! D. S i o h r i ~ .1. Amer Chem. Soc. YZ.
esis that the multiply annelated four-membered ring is responsible for this behavior was to be tested on a model of cis-tris-ohomobenzene systems having a longer bridge, e.6~.( 8 ) or
( 9 I . [271+ 201-photocyclization of the bishomobarrelenes (5)
or ( 6 ) appeared a likely method for their preparation.
These expectations were not fulfilled however; photoreactions
with various mlo,exo-bishomobarrelenes ( 5 ) (X,X'=CH2,
CHCOZCH3,0, NR'; R=C02CH3, CF3, CH3) afford almost
exclusively the trans-tris-o-homobenzeneproducts (7), which
are incapable of 3 ~ + 3 7 topening, with participation of the
three-membered ring anti to the excited chromophore. The
c.ndo,endo-bishomobarreIenes (6)-both
possibilities of
[2n + 201-addition lead to cis products [ ( 8 ) ,(Y)]-are, however, inaccessible. Regardless of the nature of the three-membered ring in (4)(X'=CH2,CHCN, 0),the second three-membered ring is only formed from the e.w side (X=CH2,
CHCO,CH,, 0, NJX') to give ( 5 ) under a wide variety of
conditions'', 31. The steric conditions and the proclivity to
rearrangement of the tricyclo[3.2.2]nonane skeleton also
thwarted attempts to bring about a transition ( 5 ) --t (6) by
way of known substitution and cyclization steps131.
This uxo-endo isomerization is however possible at the stage
of (7). The "trans-oxide" (7) (X=O, X'=CH2, R=CF3)13],
which is accessible from ( 5 ) ( X = O , X'=CH2, R = C F 3 ) on
a preparative scale by direct photoexcitation and is highly
resistant to attack by nucleophiles, undergoes smooth reaction
in a 2 N sulfuric acid solution in DMSO to give the crystalline
trans-diol ( I O U ) (72%: m.p. 112.C: r=5.87 (Hb),6.26 (H');
Jb.a=4.2,Jb.==6,Jc.d=OHz; CD3COCD3, 270MHz). The
action of c u . 1 equiv. of tosyl chloride (pyridine, 20"C, 3d)
results in 60% conversion to a mixture of unchanged ( I O U )
and the bistosylate ( 1 0 ~(colorless
)
needles, m. p. 127-128 C;
6Y41 (1971).
[2] I . . liiyrlr a n d E. Goldschniirr. Angew. Chem. 85. 824 (1973): Angew.
Chem internal. Edit. 1.767 (1973). Nachr. C'hem. Techn 21. 2x2 (1973):
('hem. Ind. ( L o n d o n ) I Y 7 3 . 1072.
[3] G. Grossniunti, Ber. Deut. C h e m G e s 22, 2298 (1889).
t f .M FWIiind R WAIL Chem Rev 6Y. 103 (1969).
[4]
[S] W
i
E . Do<vii7y and W R . Rorh. Tetrahedron I K , 67 (1962).
[6] In contrast. a iiieso-niwi valence i s o m e r m i i o n is possible under mild
conditions in the saltcyl-substituted system which IS characterized by H-honding effects a n d keto-enol taittomerism 123.
[7] I . L i / . d i r z a n d J . G. Bas. Rec. Trav. Chim Pays-Bas j Y , 173 (1940).
Simple Bridged cis-Oxa- and cis-Aza-tris-a-homobenzene Systems; Synthesis and 30+37t Isomerization[.
J
By Horst Prinzbach, Shinzo Kagabu, and Hans Fritz"]
The zero-bridged cis-tris-o-homobenzene compounds (2)
(X=CHz, CHC02CH3,O; R = C 0 2 C H j , CF3, CHI) OCCUPY
a special position in that their thermolysis proceeds not cia
the usual 30+37t cleavage to ( 3 ) (6-electron process) but
cia 20-27t cleavage to ( I ) (4-electron process)"]. The hypoth.
-
. -
&
x&~
&
.R
K
R
X
Ill
Ill
R
Ill
[*] Prof Dr. H. Prtnzhach a n d Dipl.-Chem. S. Kagabu
Lehrstuhl fur Organische Chernie der Universitit
78 Freiburg, Albertstrasse 21 (Germany)
Dr. H. Fritz
C'ibd-Geigy AG. Basel (Switzerland)
[**] This work was supported by the Deutsche Forschnngsgeineinschaft
a n d the Fonds der C'hemischen Industrie.
482
A n y w . Chem. intwnai Edir.
1 Vol. 13 ( 1 9 7 4 ) No. 7
Proof of the Electrophilic Character of Cyclopentadienylidene[**]
I
Hb
AH
( 11)
(12)
(10)
(a), X = OH,
(h), X = OH,
R
H
=
(o), x
H
(b), X = NH
= tosyl
X
0 - T o s y l , R = tosyl
( d ) , X = N3, H = H
( c ) , X = N3, R = tosyl
(C),
= 0
(c), X = NCOCH3
ca. 302,; r=4.91 (Hb), 5.23 (H“); J b , , z6 . 5 , Jb.,=3.7,
J c . , 2 I Hz; CDCI,; 270MHz) which is also found to contain
a monotosylate (colorless needles, ni. p. 106--107’-C; ca. 20%)
on chromatography (silica gel, CH2C12), shown by the ‘HNMR data (r=5.55 (Hb), 5.45 (H‘); Jb,,=4.5, Jb,,=5.3,
Jc.d2 0 Hz: CDC13, 270MHz) to be the desired em-ester
( IOh).
In accord with the conformational mobility in the skeleton
(10). evidenced inter alia by the substituent-dependent COUpling constants, cyclization of (IOb) to the cis-monooxa-tris-ohomobenzene ( 1 I a ) (colorlesscrystals, m. p. 50-51 C ; 82 YO)
can be performed under conventional conditions (sodium
methoxide, ether, 20 C). For preparation of the “cis-imine”
( 11 h ) we resorted t o the reaction sequence which has proved
its value in the synthesis ofcis-“benzene triimine” from cis-“benzene trioxide”’*’. In the presence ofa little concentrated sulfuric
acid, ( 7 ) ( X = O , X’=CH2, R = C F 3 ) reacts selectively with
an excess of sodium azide in DMSO (130 C) to form the
trans-azido alcohol ( r o d ) (colorless crystals, 68%, m. p. 82.583 C ; 1=5.98 (Hb),6.20 (H‘); J,,b=4.2, Jb,c=7.0 J c . d 2 0 H z ;
CDC13, 270 MHz). After esterification to give ( l o r ) (tosyl
chloride, pyridine; colorless needles, 96%, m. p. 105.5106.5 C). reduction and cyclization to ( I 1 b ) can be accomplished with NaAIH4 in T H F (colorless crystals, m. p. 87.5-88.5 “C,55%). Acetylation in pyridine/acetic anhydride to give
( l l c ) (m.p. 75-76°C) is almost quantitative.
The bis(trifluoromethy1)tris-o-homobenzene compounds
( I f a)--(ll c ) are more stable thermally than the unbridged
oxa- or aza-analogous diesters(’1. Above 160’C and I40 C
( I l a ) and ( I l c ) respectively-unlike the homologs (2)undergo fast, uniform, irreversible 30-371 cleavage to form
the bridged heterononatrienes ( I 2 a ) (colorless crystals, m. p.
17-18 C) and (121.) (yellowish crystals, m.p. 75-76 C).
The structures (lo)-( 12) are confirmed by physical data
(UV, IR, MS, ‘H- and 13C-NMR) and elemental analyses.
The characteristic coupling constants used for spectroscopic
identification of the cis-trons isomers ( 1 1 ) and (7), and also
the trienes ( 1 2 ) , are in good agreement with the values for
the unbridged oxa- and aza-o/n-trishom~benzenes(~~.
Received: May 13, 1974 [Z 36 IE]
German version: Angew. Chem. 86. 522 (1974)
.
.
[ I ] H Prinrbuch, W EherhucR, and C . Phrlippossiuii, Angew. Chcm. 80,
910(196X): Angew. Chem. internat Edit. 7, 887 (1968): R . S . Liir. Tetrahedron
Lett. IY6Y. 1409. H. Prin:hoch. H. Frif:. H . Huycwionn. D f f i i i i h k ? . S. Krrgohii,
and G . Philippossian, Chem. Ber. 107, 1971 (1974).
[2] H . Prinzhuch. M . Kluirs. and W M u y t ~ Angew.
.
Chem. X I , 902 (1969):
Angew. Chem. internat. Edit. 8 , 8x3 (1969). H . Prinzhuth and S. Kuyuhu,
unpublished; cf. A . d r Mrijrrr and C. Weirernryrr, Angew. Chem. 82, 359
(1970): Angew. Chem. internat. Edit Y, 376 (1970).
[3] H Prinzhuch. D. Forsrrr, D. Himklrr. and S. Kaguhu. t o be published.
[4] R. S d - w s i n y r r and H. Prinzbuch. Angew. Chem. X5, I107 (1973); Angew.
Chem. internat. Edit. 12. 989 (1973).
[5] H P r w h u c h and D. Stirschr. Angew. Chem. 82, 536 (1970). Angew.
Chem. internat. Edit. 9, 799 (1970); H . Prinzbach and D. Srusche, Helv. Chim.
Acta 54, 755 (1971).
Anyew. C‘hrm. intrmar. Edit.
By Heinz Diirr and Frans Wcrndorff”’’
According to EHT calculations[” the electrophilic or nucleophilic character ought to alternatet2]in the series of cyclic
carbenes ( 1 ) - ( 3 ) . Compound (3) has recently been shown
to exhibit the expected nucleophilic character13!
Vol. 13 ( 1974) J No. 7
!
(
li
!
!
(3,
i 7)
In the case of the carbene cyclopentadienylidene (2) essentially
three configurations are possible : the triplet G,, and the singlets
p2 (aromatic) and o2 (antiaromatic). oz-(2) should participate in nucleophilic additions whereas p2-(2) should participate in electrophilic
The ground state of (2) at
77°K is the triplet ~ - ( 2 ) [(ESR).
~]
A criterion for electrophilic or nucleophilic character of a
carbene is its rate of addition to variously alkylated olefin
pairs. In the case of (21, MOSS[^^ was unable to clarify this
CI1,
II
X
B
Table I . Phenylspiroheptadienes ( 6 u ) f 6c.J obtained by [ I +Z]cycloaddition of cyclopentadienyiidenes ( 2 ) to the styrenes 1 5 u ) - - f.i,,l [a]
~
~
~
X
..
[“/)I
PI
-.
~~~~~~~
H
p-CH3
p-CHaO
U
h
c
d
~~
~
-
~~
.-
~~
18
1.2, io.1
1 9, i 0 . 3
0.6, i0. I
0.5,&0.04
I2
17
12
7
pCI
n-Br
r
krcr [.I
f6). yield
~
.-
~
. ..
-
..
~
[a] The structure of ( 6 ) was confirmed spectroscopically: formation of a
pyraiolinc from f 5 ) and ( 4 ) wac ruled out hy control experiments.
[b] Obtained by photolysis of ( 4 ) in the styrenes ( 5 ) (high-pressure Hg-vapor
lamp. GW, filter: k > 360 nm, 20 i 1 ’ C. 60-91 7” of calculated N2).
[ c ] For determination ofk,,, the photolysis of f 4 J was carried out in cquimolar mixtures of ( S u J and one of the other styrenes ( 5 1 (75% N?).The
spiroheptadiene mixture of f 6 o ) and ( 6 x ) was filtered over silica gel and
then analyzed gas chromatographically ( 2 - - 3 m columns. 20‘%>SE 30 on
Chromosorb P A W 30-40 mesh, 16&170”C); the results ( 5 measurements)
were evaluated using eq. (2).
-
~~~
[*I
Prof. Dr. H. Durr and Dip1:Chem. F. Werndorff
Fachbereich 14, Organische Chemie der Universitiit
66 Saarbriicken (Germany)
[**] Cycloalkenecdrbenes Part I l.~-Part 10: H . Diirr. 5.Ruyc. and 8. Weis\.
Liebigs Ann. Chem., in press.
483
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simple, synthesis, homobenzene, bridge, isomerization, system, oxa, trish, aza, cis
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