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Methylenebicyclo[4.2

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2'- (1-Benzylamino-2-meth ylpropyl) cyclohexanespiro-4oxazolin-f-one (9), n = 5
Compound (6) (0.01 mol, n = 5) is dissolved in I N sodium
hydroxide solution (30 ml), a layer of chloroform is placed
under the clear solution, and (2), RZ=benzyl, R3=isopropyl(O.02 mol), is added. The mixture is well shaken and
neutralized with 2N sulfuric acid. The chloroform layer is
separated, dried, and evaporated in a vacuum. The residue
is purified over silica gel (Merck, 0.05-0.2 mm; light
petroleum/ethyl acetate 10: 1).
Received: October 31,1972 [ Z 745 IE]
German version: Angew. Chem. 85,92 (1973)
A New Method for Addition of Aldehydes to
Activated Double Bonds
Working up may be by pouring into water and extraction
with chloroform.
Table 1. Examples of the reaction of aromatic aldehydes with m,Punsaturated carbonyl compounds or nitriles:
R
R'
R2
M. p. ["C]
Yield [ %]
B. p. ["C/torr]
C6H5
H
CH3
COOC2H,
C6HS
H
CH,
COOCZH,
C6H5
CN
COOC,H,
COOC,H,
COCH,
CN
COOC,H,
COOC2H5
COCH,
76
119-1 2110.5
15&155/0.8
6M1
73
34 [a1
190J1.5
64
C6H5
C6HS
C6H 5
p-CI-C6H,
p-CI-C6H4
p-Cl-C6H4
p-Cl-C6H,
80
33
32
67
70
56
35
90
[a] B.p. 12loC/0.2 torr.
By Hermann Stetter and Manfred Schreckenberg"'
Radical addition of aldehydes to a$-unsaturated carbonyl
compounds is a known process"', but only in rare cases
are the results preparatively favorable.
We have found aldehydes ( I ) to add smoothly to a$unsaturated carboxylic esters (Za), ketones ( 2 b ) or nitriles
under the catalytic influence of cyanide ions, whereby
y-0x0 carboxylic esters (3a), y-diketones ( 3 b ) or y-0x0
nitriles are respectively formed.
Benzoins may replace benzaldehyde and Mannich bases
may replace unsaturated ketones with equally good
results. Table I contains some examples of the use of aromatic aldehydes. Examples with aliphatic and heterocyclic
aldehydes will be published shortly.
Received: October 11,1972 [Z 739IEl
German version : Angew. Chem. 85, 89 (1973)
[I] G. Sosnousky: Free Radical Reactions in Preparative Organic
Chemistry. Macmillan, New York 1964, p. 125ff.
Methylenebicyclo[4.2.1]nona-2,4,7-triener'
R'-CH=CH-C-x
..0
OHP'
:0:
By Manfed T Reetz, Reinhard W Hoffmann,
Werner Schafer, and Armin Schweig"]
+
We report here the synthesis and properties of methylenebicyclo[4.2.l]nona-2,4,7-triene (1) and 9-methylenebicyclo[4.2.l]nonane ( 2 ) . Starting from bicyclo[4.2.l]nona2,4,7-trien-9-one['] we obtained, by Wittig olefination in
ether/THF followed by gas-chromatographic separation,
a 44% yield of ( I ) : m.p. 29-32°C; NMR (CCl,), r=3.80
to 4.36 m, 4.75 s, 5.33 s, 6.66 (d, 5=6.5 Hz) in relative
intensities2.1 :I :I ;IR, 3080,2980,1675,1580,1380cm-';
UV (cyclohexane), maxima at 265 nm (log E = 3.58), 260
(3.59), 217 (3.57), shoulders at 275 (3.31), 245 (3.52). Compound (2) was prepared similarly from bicyclo[4.2.1]nonan-9-one['] in 37% yield: m.p. 42°C; NMR (CCl,),
r=5.28 s, 7.2-7.5 m, 7.8-8.9 m in relative intensities
1 :I
:6; IR, 2950,2895,1650,1460,1450 cm-'
I
CN
(2a). x
(2b), X
= OR'
= Alkyl, A r y l
-+
f? 3'
B
R-C-CH-CH2-C-X
CNO
CAN
(3a), X = OR'
(%), X = A l k y l , A r y l
The reaction can be carried out in polar solvents such as
dimethylformamide and dimethyl sulfoxide. In the examples tabulated the reaction conditions were maintained
as follows :
A solution of the unsaturated carbonyl compound or the
corresponding nitrile (0.5 mol) in dimethylformamide
(100 ml) is dropped with stirring into a solution of the
aldehyde (0.5 mol) and sodium cyanide (0.1-0.5 mol) in
dimethylformamide (150-250 ml) at ca. 35 "C, but in the
case of acrylonitrile an excess of 0.35 mol is advantageous.
The mixture is stirred until reaction is complete (1-4 h).
[*I
Prof. Dr. H. Stetter and M. Schreckenberg
Institut fur Organische Chemie der Technischen Hochschule
51 Aachen, Prof.-Pirlet-Strasse 1 (Germany)
Angew. Chem. internat. Edit. J Vol. I 2 (1973) J N o . 1
['I
Dr. M. T. Reetz and Prof. Dr. R. W. Hoffmann
Fachbereich Chemie der Universitat
3550 Marburg, Lahnberge (Germany)
Prof. Dr. A. Schweig and DipLChem. W. Schafer
Fachbereich Physikalische Chemie der Universitat
3550 Marburg, Biegenstrasse 12 (Germany)
81
7
i
rn
reveals some degree of interaction. Information about the
energy levels of the “isolated” a-systems in ( I ) is provided
by PE spectra of (2) and (4)13].From the correlation
diagram (Fig. 2) it can be seen that the HOMO of the butadiene moiety in ( 4 ) appears energetically unchanged in
( I ) because its symmetry precludes coupling with the other
n-systems. The correlation diagram also shows that the
two MOs of the ethylene units in (2) and ( 4 ) accidently
have the same energy and that their interaction in (1) leads
to significant splitting. Here MIND0/2 calculations[41
lead to the assignment of a2in ( I ) as n-bonding and a3as
a-antibonding, which indicates a predominant hyperconjugative (through bondf5])interaction. A study of further
models will have to precede a decision whether this bishomo-conjugative[61interaction in ( I ) is accompanied by
an additional, also symmetry-allowed interaction of a3
with the symmetrical butadiene MO yielding a bicyclosystem.
9
IPCeVI-
Fig. 1. Photoelectron spectrum [lo] of methylenebicyclo[4.2.t]nona2,4,7-triene ( I ) .
Compound ( I ) has three a-systems in spatial proximity of
one another, these not being conjugated in the classical
sense. Nevertheless, its photoelectron spectrum (Fig. 1)
Interaction of the a-systems could lead to polarization of
the exocyclic double bond[*,’I. We therefore studied the
I3C-NMR spectra of ( I ) and (2). The difference in
chemical shift (in ppm downfield from tetramethylsilane)
between C-9 and C-10 was found to be 41 ppm for ( I ) .
This difference is distinctly less than that for o-methylenebicyclo[n.2.1]alkanes [50-60 ppm, cf. (Z)], and the latter
is in turn considerably smaller than that for (3) (99 pprn)Ig1.
The reason for this could be that the exocyclic double
bond of ( I ) , in contrast to that of ( 3 ) gives up a small
amount of its charge to the remainder of the n-system.
Received: September 28,1972 [Z 742 IE]
Revised ’ October 20, 1972
German version: Angew. Chem 85,45 (1973)
171
121
Fig. 2. Correlation diagram of the highest occupied MOs in bicyclo[4.2.l]nona-2,4,7-triene ( 4 ) , methylenebicyclo[4.2.l]nona-2,4,7-triene
( I ) and 9-methylenebicyclo[4.2.l]nonane [2]. The numbers placed
above the peaks are vertical ionization potentials. The MOs are
classified according to the irreducible representations (a”, a’) of the C,
symmetry group.
82
[I] Part 17 of Theory and Application of Photoelectron Spectroscopy.
This work was supported by the Deutsche Forschungsgemeinschaft
and the Fonds der Chemischen 1ndustrie.-Part 16: A . Schweig, U .
Weidner, and G . Manuel, J. Organometal. Chem., in press.
[2] 7: A . Antkowiak, D. C. Sanders, G . B. Trimitsis, 3. B. Press, and
H . Shechter, J. Amer. Chem. SOC.94, 5366 (1972).
[ 3 ] P . Bischof, R. Gleiter, and E. Heilbronner, Helv. Chim. Acta 53,
1425 (1970).
[4] M . J . S.Dewar: The Molecular Orbital Theory of Organic Chemistry. McGraw-Hill, New York 1969.
[5] R . Hoflmann, Accounts Chem. Res. 4.1 (1972).
[6] S. Winstein, Quart. Rev. Chem. SOC.23, 141 (1969).
[7] M J. Goldstein and R . Hofmann, J. Amer. Chem. SOC.93, 6193
(I
971).
[8] The method of Goldstein and Hofmann 171 does not lead to a clear
prediction concerning the direction of polarization (if any) of the
exocyclic double bond in ( 1 ) , since both a positive as well as a negative
partial charge on C-9 could lead to a bicycloaromatic system.
[9] R. W Hofmann, R. Schiittler, W Schufer, and A. Schweig, Angew.
Chem. 84, 533 (1972); Angew. Chem. internat. Edit. I I , 512 (1972).
[lo] The He-I (584 8) photoelectron spectra were measured with a
PS-16 photoelectron spectrometer from Perkin-Elmer, Beaconsfield
(England).
Angew. Chem. internat. Edit. j Vol 12 (1973) / N o . I
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