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Formation of Macrocyclic Polyolefins on Autoxidation of Bifunctional Alkylenephosphoranes.

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via the intermediate anion (C1,C-) but occurs as a concerted a-elimination of LiCl from the complex of (2) with ether
or amineIQl.
It is noteworthy that the temperatures of decomposition of
(2) in triethylamine and acyclic ethers are the same. This
fact may serve as further evidence for the above mechanism, because, according to Lewis and Brown[1oJ,
complexes
of alkyllithium compounds with dialkyl ethers and corresponding trialkylamines are equally stable.
Received: February 28,1972 [Z 610 IE]
German version: Angew. Chem. 84, 527 (1972)
Formation of Macrocyclic Polyolefins
on Autoxidation of Bifunctional
Alk ylenephosphoranes
By Hans Jiirgen Bestmann and Hans Pfiiller["
Dedicated to Professor Georg Wittig on his 75th birthday
Autoxidation of alkylenephosphoranes (ylides)of structure
R-CH=P(C,H,),
affords olefins R-CH=CH-R[']
and triphenylphosphane oxide. If bifunctional alkylenephosphoranes (bisylides) ( I ) are used, cycloolefins (2) ['* 31
are obtained. ( I ) , R=-(CH,),--,
reacts with cyclizing
dimerization to yield 1,5-cyclooctadiene[ZJ.Our further
investigations have given the following results :
If the structure of the starting bisylide of type ( I ) permits
intramolecular ring closure on autoxidation, yielding a
five-, six- or seven-membered ring, such a ring is formed
either mainly or exclusively. A compound such as ( 3 ) ,
however, does not yield any medium-size ring compounds,
e. g. ( 4 ) , but macrocyclic polyolefins such as ( 5 ) -(9) are
obtained by dimerization, trimerization etc. Further
examples are collected in Table 1.
Correct analytical data and NMR and mass spectra are
available for all the pure mono-, di-, and tri-mers listed in
the Table. Formation of further cyclooligomers, of which
in some cases only the trimer could be isolated, can be recognized by C, H analyses, NMR spectra, and clearly from
the field ions in the mass spectrum; here the molecular ions
gave the strongest mass lines, e.g. (6) M' =414, ( 7 )
M' = 552, (S} M' = 690, (9) M' = 828. After hydrogenation, correspondingly heavier molecular ions appear.
For examples 4,6 and 7, the proportion of cis,cis-isomer in
the dimer was determined (silver nitrate complex). It was
then shown that this isomer was formed preferentially:
cis,cis-1,9-cyclohexadecadiene.2AgN03, m.p. 142 to
143"C, 78 % ; cis,cis-l,l0-dioxa-5,14-cyclooctadecadiene~
2AgN03, rn.p. 153"C, 62%; &,cis-1,ll-cycloeicosadiene.2AgN03, m.p. 135-136°C (m.p. 136-137°C[61)
78 %.
All the bifunctional alkylenephosphoranes, except that
used for No. 5 of the Table (poor yield), are sparingly
soluble in dimethyl sulfoxide. We therefore assume that
formation of macrocyclic rings on autoxidation of the bisylides in an intermolecular Wittig reaction (according to
begins with formation of a cis-double bond. SubRef. [I])
sequently, either an intramolecular reaction may occur or
the chain may grow by further intermolecular C=C junctions before ring closure to the cyclooligomer follows.
1,lI-Cycloeicosadiene ( 5 ) and oligomers (6)-
(9)
1,1O-Decamethylenebis(triphenylphosphonium bromide)
(49.5 g, 0.06 mol) is converted by the dimethyl sulfinate
rnethodI4' into a suspension of the corresponding bisylide
in dimethyl sulfoxide, through which, in the apparatus
(3)
[*] Prof. Dr. H. J. Bestmann and Dr. H. Pfuller
Institut fur Organische Chemie der Universitat Erlangen-Numberg
8520 Erlangen, Henkestrasse 42 (Germany)
508
described previously"], oxygen is passed with ice-cooling
and magnetic stirring until the ylide precipitate has dissolved and a brown solution results (oxidation time 3 h ;
Angew. Chem. internat. Edit. i Vol. 11 (1972) i No. 6
Table 1. Autoxidation of bisylides. The bisylides were prepared from the phosphonium bromides in dimethyl sulfoxide with the dimethyIsuIfinate ion
[4] as base [5].
No
Ylide
Monomer
Yield
X=P(C,H,),
["OI
B p ["C/torr]
1
c
62 11
.
2
C
CH=X
CH=X
CH=X
CH=X
Yield
Dimer
Total
yield
B. p. ['C,torr]
Cyclooligomers
Yield [",,I
B.p. ['C/torr]
2.7
(51/0.4)
Ci8H,,(4.1 ; 112/0.4);
C24H40; C3OH5O;
6
["<,I
22 [a]
[ ",*I
C36H60
0
1.5
48/0.001
C,,H3,(2.7; 116/0.001) 2.7
12
(8910.05)
C,,H,, (5.5; 130/0.05)
C32HS6; C 4 0 H ? 0
C4MH84
11
2.3 [b]
-
5.0
(I22i0.3)
C,,H,M
1.5
3
22 [a]
4
5
C2MH4M
6
7
1.2 [b]
8
9
r n C " C=H"= X
53
54,'14
10
30
68/14
If
26
68/14
12
32
77/14
[a] Yields were determined by means of the dibromides.
[b] Identified by gas chromatography.
[c] NMR, 20'C: T = 8 ppm (non-olefinic protons); -75 to
3.2
14310.02
?
- 100°C: Splitting to a multiplet because of slower conformational change
oxygen uptake 1140m1, 85%). The solution is then left
overnight, after which it is extracted with light petroleum.
The extracts are united, washed twice with water, dried
over sodium sulfate, filtered and freed from solvent. The
residue is boiled for a short time under reflux with methyl
iodide (3-4 ml), then treated with light petroleum (200 ml),
which precipitates the triphenylphosphane from the extract
as methyltriphenylphosphonium iodide. The filtrate therefrom is concentrated and poured on an aluminum oxide
column (length 20 cm, diameter 1.5 cm, neutral A1,0,
Woelm, activity 11) for removal of triphenylphosphane
oxide. Elution is with cyclohexane. On evaporation of the
cyclohexane the hydrocarbon mixture separates as a mass
of colorless crystals. ( 5 ) distils at 123-124"C/0.15 torr
(yield 1.1 g, 13.7%). The residue is distilled in a rotating
Angew. Ckem. internat. Edit.
Vol. I 1 11972) / N o . 6
tube at 180-240"C/0.001 torr, affording 1.4g (17%) of
( 6 ) , (7), (8), and (9).
Received: March 16, 1972 [Z 620 IE]
German version: Angew. Chem. 84, 528 (1972)
[l] H . J . Eestmann and 0. Kratzer, Chem. Ber. 96, 1899 (1963).
[2] H . J . Eestmann, H . Hiiberlein, and 0 . Kratzer, Angew. Chem. 76.
226 (1964); Angew. Chem. internat. Edit. 3, 226 (1964).
[3] H . J . Bestmann, H . Hiiberlein, H . Wagner, and 0. Kratzer, Chem.
Ber. 99, 2849 (1966).
141 E . 1. Corey and M . Chaykocsky, J. Amer. Chem. SOC.84.866 (1962).
[5] For the examples described in [ 2 ] the bisylides were prepared by
either the sodium amide or the organolithium method; H . J . Besimann,
Angew. Chem. 77. 609 (1965); Angew. Chem. internat. Edit. 4. 583
(1967).
[6] J . Dale. A . J . Huhert, and G . S . D. King, J. Chem. SOC.IY63. 73. 13
509
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bifunctional, alkylenephosphoranes, formation, autoxidation, macrocyclic, polyolefins
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