Note: Descriptions are shown in the official language in which they were submitted.
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Stereospecific syntheses of olefins according to
Wittig's reaction by means of salt-free ylides are already
known (see: Angew. Chem. 78 (1966), 677). Such ylide solutions
had to be prepared hitherto according to the technically
complicated solium-amide method (Liebigs Ann. Gheml. 619,
(1958), 10; Angew. Chem. 77 (1965), 609).
The present invention provides an improved process
for preparing cis-olefins of the formula
H H
R - C = C - Rl III
Wherein R is straight-chain or branched (Cl-C15) Alkyl or
(C2-C15) alkenyl and R is a straight-chain orobran¢hed
(Cl-C20) alkyl or (C2-C20) alkenyl group both being optionally
substituted in 3-position or in farther position relative to
the double bond by hydro~y, lower carbalkoxy or (Cl-C3) acyloxy,
which comprises dissolving an alkali metal or alkaline earth
metal in a hexaalkylphosphoric acid triamide, adding to the
solution obtained a phosphonium salt of the formula
R-CH2-P(C6H5)3Br, I
And adding to the reaction mixture obtained an aldehyde of
the formula
Rl _ C~0 II
And isolating the product obtained by known methods.
Suitable alkali metals or alkaline earth metals are
preferably, sodium and magnesium, especially potassium,
furthermore calcium, strontium and barium.
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The alkyl groups in the hexaalkylphosphoric acid
triamide may be identical or different and preferably from
1 to 4, especially 1 or 2 carbon atoms. The well-known easily
obtainable hexamethylphosphoric acid triamide is especially
preferred.
The process is generally carried out as follows:
Crushed alkali metal or alkaline earth metal is introduced under
nitrogen atmosphere into the hexaalkylphosphoric acid triamide
while stirring or shaking, whereby the original blue color of the
solution turns reddish-brown. For reasons of simplicity the dis-
solution is effected at room temperature, but may be carried out
generally at temperatures of from 10 to 80 C, preferably from 15
to 30 C. When the alkaline earth metal or alkali metal has dis-
solved completely after approximately 1 to 3 hours, an equivalent
quantity or optionally an excess of up to 20 %, preferably up to
10 % of a phosphonium salt of formula 1, wherein R preferably
contains up to 10 carbon atoms, is added to the solution. The
phosphonium salts may be obtained by known processes for instance
by reacting corresponding a-bromosubstituted compounds with
triphenyl phosphine. The phosphonium salt may be added as much
or preferably in the form of a suspension in hexamethylphosphoric
acid triamide. The quantity or hexamethylphosphoric acid triamide
required per millimole of phosphonium salt or per milliequivalent
or alkali metal or alkaline earth metal is generally in the range
from 0.5 to 5 ml or more, preferably from o.8 to 2 ml. The upper
limit is not critical.
An aldehyde of formula II is then added to the ylide
solution obtainedO In these aldehydes R' preferably contains 2
to 15 carbon atoms and may be substituted (preferably in terminal
--3--
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position by hydroxy, lower carbalkoxy or lower acyloxy, preferably a formyloxy
or acetoxy group.
The reaction mixture is stirred at the chosen reaction temperature
until the reaction is complete ~at room temperature after about 8 to 15 hours)O
The olefin formed is isolated in known mannerJ for example by distillation or,
in the case of higher boiling compounds, by pouring on ice and subsequent
extraction.
The aldehyde may also be prepared in situ by oxidizing the ylide
solution, for example by means of dry oxygen. In this manner symmetrical
cis-olefins of the formula
H H
R - C = C - R IIIa
are obtained. The compounds manufactured by the process of the invention have
a degree of purity of more than 95% according to gaschromatographic and
spectroscopic analyses. They are valuable intermediates for organic syntheses
and a series of these compounds has a pheromone effect on a number of
lepidoptera.
The following examples illustrate the invention.
E X A M P L E 1: Preparation of Ylide solution
-
Finely cut potassium was introduced in absolute hexamethylphosphoric
acid triamide under a nitrogen atsphere. The dark blue solution obtained
heated after about 15 minutes turning reddish-brown. After 1 to 3 hours,
when the potassium was completely dissolved, a suspension of an equivalent
quantity of a phosphonium salt of formula I in absolute hexamethylphosphoric
acid triamide was added.
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E X A M P L E 2: PreParation OI cis-octene (4)
=
A ylide solution was prepared from 2.2 g (55 millimoles)
of potassium and 20 g t50 millimoles) of triphenyl-n-butyl
phosphonium bromide in 100 ml o~ hexamethylphosphoric acid -
triamide according to example 1 and 4.0 g (55 millimoles) of
butyraldehyde were added. dfter 12 hours the octene(4) obtained
was distilled from the reaction solution. It was taken up in
pentane, the solution washed subsequently with diluted sulfuric
acid, sodium hydrogen sulfite and water and dried with sodium
sulfate. The pentane was removed from the octene(4) by distil-
ling it over a Vigreux column. The remaining crude product was
distilled.
Boiling point760 = 120C
Yield : 4 3 g - 76 %
E X A M P L E 3: Pre~aration of cis-octane(4) by autoxidation
Dry oxygen was passed through an ylide solution preapared
in an analogous manner to example 2. The batch was worked up
as in example 2.
Boiling point760 = ~20C
Yield: 2.0 g = 70 %
E X A M P L E 4: PreParation o~ cis-9-alkenol-1-acetates
An ylide solution was prepared from 0.94 g (24 millimoles)
of finely cut potassium in about 50 ml of absolute hexamethyl-
phosphoric acid triamide and 24 millimoles of triphenylethyl
phosphonium bromide. The dimethylamine formed in this process
was removed in vacuo as far as possible while excluding humidity.
After stirring for 4 hours 20 millimoles (4.0 g) of 9-aceto~y-
nonanal were added while cooling with water, the whole was
29 stirred over night and the reaction mixture was poured on ice
-- 5 --
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water acidified with a small quantity of diluted sulfuric acid.
The unsaturated ester was extracted with n-hexane.
The combined he,~ane extracts were washed with diluted sulfuric
acid in order to remove small quantities of hexamethylphos-
phoric acid triamide. Unreacted aldehyde was separated from the
unsaturated ester via the hydrogensulfite addition compound and
triphenylphosphine formed during the reaction via triphenyl-
methyl phosphoniu~ iodide. Small quantities of triphenyl
phosphine oxide extracted by n-hexane completely cristallized
during the night at about -25C and were filtered of~ with
suction. After drying the n-hexane was removed in vacuo and the
colourless oily residue was distilled.
The yield was 2.2 g (50 %) of cis-9-undecenol-1-acetate.
Boiling pointO 01 84C.
In the same manner a number of other compounds having
pheromone effect on various lepidoptera were prepared by
varying R, for example,
cis-9-dodecenol-1-acetate boiling pointO 1 101 - 102C
(R = n-propyl) yield 2.3 g ~51~).
This compound has a repellent effect on males of the pine
shoot moth (Evetria buoliana Schiff.) and is the sexual
attractant of males of Paralobesia viteana.
cis-9-tridecenol-1-acetate boiling pointO 01 97C
(R = n-butyl) yield 2.6 g (54 %)
cis-tetradecenol-1-acetate boiling pointO 01 102 - 104C
(R = n-pentyl) yield 2.6 g (51 ~)
This compound is the sexual attractant of females o~ -
Spodoptera frugiperda, as well as a component o~ the pheromone
29 of Adoxophyes orana. ~ -
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cis-9-pentadecenol-1-acetate boiling pointO 01 118C
(R - n-hexyl) yield 2.8 g (57 %)
E X A M P L E 5: Preparation of cis-11-alkenol-1-acetates
These substances were prepared in an analogous manner
as in example 4, by using 4.6 g (20 millimoles) of 11-acetoxy-
undecanal instead of 9 acetoxynonanal.
The following compounds having a pheromone effect were
obtained ~
cis-11-tridecenol-1-acetate boiling pointO 01: 101C
(R = n-ethyl) yield : 2.5 g (52%)
cis-11-tetradecenol-1-acetate boiling pointO 15:103C
(R = n-propyl~ yield : 2.3 g (45%)
This compound is the sexual attractant of the ~emales of
Argyrotaenia velutinana, Choristoneura rosaceana, Ostrinia
nubilalis, Ancylis spectrana, Zeiraplera diviana and a com-
ponent of the pheromone of Adoxophyses orana. It also has an
attracting effect on cabbage moth.
cis-11-hexadecenol-acetate boiling pointO 1: 108C
(R = n-pentyl) yield : 2.6 g ~47 %)
E X ~ M P L E 6: PreParation of cis-9-tetradecene-ol-1-
formiate
- 3.8 g of 9-formyloxynonanal were added to an ylide
solution of 0.94 g of potassium and 9.3 g of n-pentyltriphenyl
phosphonium bromide prepared according to example 4. After
stirring for 12 hours the mixture was worked up as in example 4.
The yield was: 2.5 g (52 %) of cis-9-tetradecene-ol-1-
formiate
boiling point:O 01 97 to 100C
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The compol~d had an attracting effect on males of Heliothis
zea 9
E X A M P L E 7~ Preparation of 2-methyl-cis-7 octadecene
0.94 g (24 millimoles) of finely cut potassium in about
50 ml of absolute hexamethylphosphoric acid triamide were
reacted with 10.92 g (24 millimoles) of isooctylphenyl phos-
phonium bromide giving the corresponding ylide, this was then
reacted~with 3.8 g (20 millimoles)of n-undecanal giving the
olefin. The whole was worked up as in example 4.
The yield was 2 g (37 %) of 2-methyl-cis-7-octadecene,
boiling point: 125 to 129C/0.2 mm Hg.
When reacting this compound with m-chlorobenzoic acid
the corresponding cis-epoxide was obtained, the sexual attracant
of the great gipsy moth ~Lymantria dispar).
E X A M P L E 8:
Preparation of cis-9-trans-12-tetradecadienol-1-acetate
4.0 g of acetoxynonanal was added dropwise to an ylide
solution prepared according to example 4 by using (E-3-pen-
tenyl)-triphenyl phosphonium bromide. The mixture was stirred
for 12 hours at room temperature and worked up as in example 4.
Yield: 2.1 g (43 %) of cis-9-trans-12-tetradecadienol-1-
acetate, boiling pointO o4 110 to 112C
This compound is the sexual attractant of the females of
Plodia interpunctuella, Anagasta kuhniella and Laphygma exigua.
It is moreover a component of the pheromone o~ cadra cutella
and prodenia eridiana.
_
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X A M P L E 9
Pre~aration of cis-9-unsaturated Propionates and butYrates
The preparation was carried out as in example 4, but
using, instead o~ the 9-acetoxynonanal, either 3.96 g (20 milli-
moles) of 9-oxynonyl-1-propionate or 4.24 g (20 millimoles) of
9-oxynonyl-1-butyrate. The following compounds were obtained:
cis-9-dodecenyl-1-propionate
boiling pointO o5 96 - 97C yield 2.83 g (62 %)
cis-9-tetradecenyl-1-butyrate
boiling pointO 01 118 - 121C yield 2.97 g (55 %)
E X ~ M P L E 10
,PreParation of 9-unsaturated carboxylic acid methyl esters
The corresponding ylide solutions were reacted with 9-oconanoic
acid methyl ester (3.4 g, 20 millimoles) as in example 4.
15 The following substances were obtained:
cis-9-dodecenoic acid methyl ester
boiling pointO o3 82 - 83C yield 2.08 g (49 %)
cis-9-trans-12-tetradecadienoic acid methyl ester
boiling pointO 05 97 - 99 C yield 2.34 g (50 %)
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