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Complexes of Short-Chain Oligo(ethylene Glycol Ethers) Bearing only one Rigid Donor End Group.

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Divinyl Ketone as Michael Acceptor
By Dietrich Spitznery]
In the course of our investigations on the synthesis of tricyclic sesquiterpenes such as seychellene ( I ) we attempted the
preparation of the closely related compound 3,8-dimethyltricyclo[5.3.1.03~8]undecan-2,6-dione(6) in one operation via
three consecutive Michael additions.
Experimental.
D
c
H
\\
3
X
( I ) , X = CH2
(6), X = 0, 0 on C - 6
i n s t e a d of CH3 and H
In view of the previous finding that a cyclohexadienolate
of type (2), generated under kinetically controlled conditions,
reacts with acrylates via double Michael addition to give
5-oxobicyclo[2.2.2]octane-2-carboxylates['1, we used instead
of an acrylate the potentially divalent Michael acceptor divinyl
ketone (3)"I.
It is known[31that in the aprotic Michael addition, polymerization proceeds much faster than the addition reaction with
the desired donor. Nevertheless, we obtained a 1: 1 adduct
(EI-MS: m/e=206, M + )of ( 2 ) and ( 3 ) . Both the IR spectrum
[film; 3100 (C-CH'),
1670cm-' (enone)] as well as the 270MHz 'H-NMR
[CDC13; 6 = 6.40-5.81 (ABX,
vinyl), 2.72 (t, 2'-H), 2.36 (br. s), 1.89 (br. s, CH3), 1.75 (br.
s, CH3), several multiplets between 2.36 and 1.551 and especially the I3C-NMR spectrum[41[CDC13; 6=200.4 (two CO
groups distinguishable only on addition of Y b ( f ~ d ) ~153.6,
);
136.3, 130.2, 127.8 (olefinic C); 44.6 (CH); 37.0, 31.5, 27.8,
24.3, (CH'); 21.0, 10.8 (CHs)] afford proof of formation of
(7), i.e. that only the first of the three possible additions
takes place. Intramolecular secondary additions leading to
(6) do not occur.
A solution of ( 3 ) (1.3 equiv.) in THF is added dropwise
at - 70°C in the presence of an inert gas to a tetrahydrofuran
solution of (2), prepared from 2,3-dimethyl-2-cyclohexene(9)
and lithium isopropyl(cyclohexyl)amide['] (molar ratio 1 : 1.1).
The mixture is stirred at this temperature for 15min and
then neutralized with 1 N HC1 and extracted with ether. The
oil obtained after drying and concentration of the organic
phase is distilled in a bulb tube: After removal of forerunnings
(mainly unreacted ( 9 ) ) , (7) distils over at 90-11O0C/O.03
torr as a pale yellow oil (18 %) which crystallizes on storage
in an ice-box.
Received: Januar 10, 1978 [Z 906 IE]
German version: Angew. Chem. 90,213 (1978)
CAS Registry numbers:
( 2 ) , 65636-27-3; (3), 1890-28-4; ( 7 ) , 65636-28-4; (8), 65636-29-5; (9), 112220-9
[l] R. A. Lee, Tetrahedron Lett. 1973, 3333.
[2] H. A. P. de Jongh, H . Wynberg, Recl. Trav. Chim. Pays-Bas 82, 202
(1963).
[3] R. K. Boeckman, Jr., J. Am. Chem. SOC. 96, 6179 (1974); G. Stork,
J . Singh, ibid. 96, 6181 (1974).
[4] I thank Priv.-Doz. G.Hi?&, Berlin, for recording the I3C- and 'H-NMR
spectra.
[5] S. Danishefsky, B. H. Migdalof, J. Am. Chem. SOC. 91, 2806 (1969).
Complexes of Short-Chain Oligo(ethy1ene Glycol
Ethers) Bearing only One Rigid Donor End Group[**]
By Ulrich Heimann and Fritz Vogtle"]
While simple oligo(ethy1ene glycol dimethyl ethers) such
as pentaglyme (I), n = 3, are reported"] not to form crystalline
complexes with salts of alkali and alkaline earth metals['],
such complexes are readily obtained with "noncyclic crown
ethers" (2), n 2 1,which are rendered rigid by aromatic donor
end groups (E)I31.
While ( 3 ) is capable of undergoing double Michael addition
under the usual conditions, it reacts with anions such as
(2) as monovalent acceptor under aprotic conditions, and
thus proves to be a possible C-5 synthon for terpene and
steroid syntheses. By way of example, an adduct analogously
synthesized from ( 3 ) and isophorone reacts regioselectively
with tert-butyl acetoacetate under conventional protonic conditions to give the monoadduct (8) (55.6 %), which after hydrolysis and decarboxylation can be subjected to further aldol
condensation[51.
Trialkylsilyl groups in the a-p~sition[~]
of ( 3 ) should have
a pronounced effect on the course of this aprotic Michael
addition.
[*] Dr. D. Spitzner
lnstitut fur Chernie der Universitat Hohenheirn
Garbenstrasse 30, D-7000 Stuttgart 70 (Germany)
Angew. Chem. I n t . Ed. Engl. I7 (1978) No. 3
I2 I
111
This communication considers whether a single donor end
group E suffices to permit isolation of crystalline complexes
of alkali metal ions. If this is the case, the next question
to be answered concerns the minimum length of the oligo(ethy1ene glycol ether) chain in the limiting case.
n0hi
h
0 E
R-0
I3 I
[*] Prof. Dr. F. Vogtle, Dip].-Chem. U. Heimann
Institut fur Organische Chemie und Biochemie der Universitat
Gerhard-Domagk-Strasse 1, D-5300 Bonn (Germany)
[**I Work supported by the Deutsche Forschungsgemeinschaft and the
Fonds der Chemischen Industrie.
197
We found that one end of the oligo ether chain may
exhibit less donor strength if the other donor end group
E is a strong coordinating one. Thus, in the case of tetraand hexa-dentate neutral ligands ( 4 ) - ( 6 ) with an 8-quinolyloxy group at one end of the chain and a I-naphthyloxy,
phenoxy, or even methoxy group at the other end, we still
obtained crystalline complexes with a series of salts (Table 1).
Just one effective end group was also sufficient to permit
isolation of crystalline alkali metal ion complexes in the case
of f 7 H 9 ) .
ligand/complex topologies. These systems permit almost continuous variation of the balance between lipophilic and hydrophilic properties, and of complex stability constants and complexation kineticsf61.Such versatility is significant for some
potential applicati~nsl~l.
Received: December 15, 1977 [Z 898a IE]
German version: Angew. Chem. 90,211 (1978)
CAS Registry numbers:
( 4 a ) , 65496-10-8; ( 4 b ) , 65496-11-9; ( 5 a ) , 65496-12-0; ( S b ) , 65496-13-1;
( 6 a ) , 57310-80-2; ( 6 b ) , 65496-14-2; (6c), 65496-15-3; (7a), 65496-16-4;
( 7 b ) , 65496-17-5; ( a a ) , 65496-18-6; (Bb), 65545-78-0; ( p a ) , 65496-19-7;
( 9 b ) , 65496-20-0
Table 1, complexes from top to bottom:
65504-68-9; 65504-70-3; 65504-72-5; 65504-74-7; 65504-76-9; 65504-78-1;
65504-80-5; 65504-82-7; 65504-84-9; 65504-86-1
111
171
19/
IBI
The chain segment adjacent to E can enclose the cation
in a planar fashion; a second donor end group is apparently
not required14] for formation of crystalline complexes but
can nevertheless exert a stabilizing action and, above all,
raise the complexation constant[5!
C . J . Pedersen, J. Am. Chem. SOC.89, 2495, 7017 (1967).
[2] Nor had we hitherto made such an observation in numerous complexation experiments with noncyclic neutral ligands [ 3 ] .
131 E. Weber, F . R g t l e , Tetrahedron Lett. 1975, 2415; F. Vogtle, H . Sieger,
Angew. Chem. 89,410(1977);Angew. Chem. Int. Ed. Engl. 16,396 (1977);
W Rasshofer, F. Rgtle, Chem. Ber. 1 1 1 (1978), in press; W Rasshofer,
G . Oepen, F . Irdgtle, ibid. I l l , 419 (1978).
[4] X-Ray structure analyses of selected complexes are in progress: Prof.
Dr. W Saenger et a/., Gottingen.
151 Cf.H . Sieger, F. Vogtle, Angew. Chem. 90, 212 (1978); Angew. Chem.
Int. Ed. Engl. 17, 198 (1978).
[6] Survey: B. Tummler, G . Maass, E. Weber, W Wehner, F . Vogtle, J. Am.
Chem. SOC. 90,4683 (1977).
[7] Cf. J . G . Schindler, R . Dennhardt, W Simon, Chimia 31, 404 (1977);
J . G. Schindler, Biomed. Tech. 22, 235 (1977).
Table 1. Ligands synthesized and their complexes with alkali metal salts.
Ligand [a]
Chain
length
Complex [a, b] Stoichiometry
with
m. p.
I"C1
NaC104
KSCN
NaC104
KSCN
NaSCN
NaC104
KSCN
[dl
NaC104
1:l
1:l
130-131
152
124125
91- 92
142
11-5118
88-90
1:l
99-100
1:l
73-74
n
2
3
2
3
1
2
3
2
3
2
3
2
3
M
NaCIO,
[dl
NaC104
1:l
1:l
1:l
1 : l [c]
1:l
1:l
By Heinz Sieger and Fritz Egtle[']
This study of the relation between structure and complexation of simple neutral ligands was instigated by the following
observations: a) glyme compounds of type (I) do not form1''
crystalline alkali metal ion complexes and b) "noncyclic crown
ethers" ( 2 ) bearing rigid donor end groups (Do =donor center
in the end group) readily form such
102
[a] Correct analytical data and/or high resolution mass spectra were obtained
for all ligands and complexes.
[b] All complexes are colorless.
[c] Also contains 0.5 mol of H20.
[d] Alkali metal salts complexed; however no simple stoichiometry between
ligand and salt could be detected,
Comparison of the 'H-NMR spectra of the naphthol ether
( 4 a ) and the phenol ether ( 5 a ) provides information about
the arrangement of the ends of the chain carrying no donor
group in the complex: while a large upfield shift of the aand P-quinoline protons is observed on transition from the
free ligand to the complex in the case of ( 4 a ) , only the
a-quinoline proton exhibits an upfield shift in the complex
of ( 5 a). Since spatial proximity can be assumed between
the quinoline and the naphthalene ring and the benzene ring,
respectively, the difference can be interpreted as due to the
larger anisotropic region of the naphthalene ring. The mutual
orientation of the chain ends in the novel complexes and
the arrangement of the central ion and the donor centers
are being examined by means of X-ray structure analysis14!
It is possible, by variation of the donor end group E and
of the Iipophilic chain end, to construct a whole series of
198
Alkaline Earth Metal Complexes of Simple
Oligo(ethy1ene Glycol Ethers)[**]
The key question arising from X-ray structure comparisons
of several complexes of ligands (2)I2l is: how short can the
chain be and what is the minimum donating ability of the chain
ends required for oligo(ethy1ene glycol ethers) to still just
form crystalline complexes with alkali or alkaline earth metal
salts?
Careful crystaIIization experiments showed that the
polyethers (3) and ( 4 ) bearing two donor-free but rigid aryl
groups at their ends and containing at least five ether oxygen
atoms ( n 2 1) gave crystalline complexes, especially with alkaline earth metal ions. Some of the complexes, including the
alkali metal ion complex of (3 c), are listed in Table 1.
[*I Prof. Dr. F. Vogtle, Dipl.-Chem. H. Sieger
Institut fur Organische Chemie und Biochemie der Universitat
Gerhard-Domagk-Strasse 1, D-5300 Bonn (Germany)
[**I Supported by the Deutsche Forschungsgemeinschaft and the Fonds
der Chemischen Indusrrie.
Angew. Chem. I n t . Ed. Engl. 17 (1978) No. 3
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