Note: Descriptions are shown in the official language in which they were submitted.
This inventicn relates to an improved chemical process
and more particularly it rel.ates to an improved process for
the manufacture of certain butenolide derivatives which are
useful per se, or as the active ingredient in herbicidal
compositions, for the control of the parasitic weeds Striga
hermonthica, Striga asiatica (lutea), Orobanche crenata,
Orobanche ramosa an~ Orobanche aegyptiaca.
_
It is known that compounds of the formula I or II:
r~
x CH - ol~ ~ ~X~CH-O~ ~
I II
wherein R is hydrog_n or an alkyl radical of one to five
carbon atoms, X rep~esents a single bond or a -CH2- linkage and
Y represents two hy~rogen atoms, an additional bond or an epoxy
group, may be prepared by reacting an alkali metal salt of the
formula IA or IIA:
~X ~ H-O '~1 ~ X ~ _H-O M
IA IIA
wherein X and Y have the meaning.stated above, and M~ is the
ion of an alkali metal, with a methanesulphonate derivative of
the formula III:
C~3.S02.0 ~ ~ O ~ 0
III
wherein R has the meaning state~d above.
The said process suffers from the disadvantage -that the
methanesulphonate derivative used as a reactant tends to be
rela-tively unstable and is prone to polymerize to a certain
extent on keeping.
It has now been found, and herein lies the basis for the
present invention, that if the said methanesulphonate derivative
is replaced by the corresponding chloro derivative, the said
dlsadvantage is reduced or obviated.
.lO According to the invention there is thus provided an
improved process for the manufacture of a compound of the formula
V: R
A lX~CH ~ ~-I
B
IV
wherein R is hydrogen or an alkyl radical of one to five carbon
atoms, X represents a single bond or a -CH2- linkage and A and
B each stands for a hydrogen atom or they may be joined, together
with the two adjacent carbon atoms, to form the ring structure
/
/ .
Y ~
wherein Y represents two hydrogen atoms, an additional bond or
an epoxy group, which comprises reac-ting a compound of the
formula V:
A ~ X \ ~ CH-
B ~ o ~ O
wherein A, B and X have t.he meaning stated above and M~ is -the
ion of an alkali metal, with a chloro derivative of the formula
VI:
_~_ /
Cl ~ O / ~
VI
wherein R has the meaning stated above.
The reactant of the formula V may be a compound wherein
the alkyl radical R is methyl, ethyl, n-propyl or isopropyl
and of ~hese, methyl is preferred. The representation X is
preferably a single bond and the representation Y i.s preferably
an additional bond. As a suitable compound of the said formula
there may be mentioned for example the sodium salt of 3-hydroxy-
methylene-1,4-butyrolactone (:Eormula V wherein X is a sing].e
bond, A and B are hydrogen and M is sodium); the sodium salt of
4-hydroxymethylene-1,5-val.erolactone (formula V wherein X is a
-CH2- linkage, A and B are hydrogen and M is sodium); and the
sodium salt of the y-lactone of 4-hydroxycyclopentenyl-5-(~-
formylacetic acid) as represented by formula V wherein X is a
single bond, Y is an additional bond and M is sodium.
As a suitable compound of the formula VI there may be
mentioned for example 5-chloro-but-2-enolide and 5-chloro-3-
methylbut-2-enolide.
The reaction may conveniently be carried out in the
presence of an organic solvent or diluent, such as anhydrous
glyme or tetrahydrofuran, and at ambient temperature of from
about 15C to about 25C.
Particularly useful compounds which can be prepared
according to the process of the present invention are the compounds
~4~
of formula IV where n R is methyl, A and B are hydrogen and X
is a single bond or a -CH2- linkage and the compound of the
formula IV wherein P~ is methyl, X is a single bond and Y is an
additional bond.
~ he invention is illustrated, bu-t not limited, by the
following examples describing the preparation of compounds
according to the process of the invention.
Example 1
-
Preparation of the Chlorobutenolide (VI; R=CH3)
A solution ol the lactol (16.0g) of the formula:
CH3
HO O
in glyme (50 ml), is added dropwise to a stirred mixture of
thionyl chloride (30.0g) and anhydrous sodium carbonate (7.44g)
over a period of 3 hours. The mixture is maintained at about
40 during this period and is heated to 80 for 1 hour. It is
then cooled, filtered and the solvent removed in vacuo to give
the chlorobutenolide (IV; R-CH3) which may be purified by
distil]ation at 60/2 r~m~ Found: C,45.42; H,3.79; C5H5ClO2
requires C,45.28; H,3.77.
Preparation of_the Dilactone (IV; R=CH ; X=single bond; Y=
additional bond) 3
A mixture of the sodium salt of the ~-lac-tone of 4-hydroxy-
cyclopentenyl-5~ ~ormylacetic acid) (V; M=Na; X=single bond;
Y-addit~onal bond) (0.87g) and the chlorobu-tenolide (0.67g) in
anhydrous glyme (10 ml) is s-tirred at room temperature for 24 hours.
The mixture is then poured into ice-water (50 ml) and extracted
with chloroform (3 x 50 ml). The combined extracts were washed
with saturated salt solution, dried over sodium sulpha-te and
evaporated to dryness to give a semi-crystalline residue (1.13y).
--5--
Recrystallization from methylene chloride-ether mixture gave
the desired dilactone ~0.98g; 80%),m.p. 128-130C. and having
the formula: CH3
~ CH- O
Example 2
By replacing the sodium salt in Example 1 ~ith an
equivalent amount of the sodium salt of 3~hydroxymethylene-1,4-
butyrolactone and following a similar procedure as in Example 1,
there is thus obtained the compound of the formula IV (R--CH3; A
and B = H; X=single bond), m.p. 92-94C. and having the formula:
CH3
CH- O
0~0
Example 3
_ _
By replacing the sodium salt in Example 1 with an
equivalent amount of the sodium salt of 4-hydroxymethylene-1,5-
valerolactone and following a similar procedure as in Example 1,
there is thus obtained the compound of formula IV (R=CH3; A and
B=H; X=-CH2-), m.p. 105-107C. and having the formula:
CH- O ~ oCH3
f~
~ o/bO
Example 4
By replacing the sodium salt in Example 1 with an
equivalent amount of the sodium salt of the ~-lactone of 2-
hydroxycyclopentane-formylacetic acid and following a similar
procedure as in Example 1, there is thus obtained the compound
of formula IV (R=CH3; X=single bond; Y-2H) having the formula:
CH
~r 3
c~-o ~o /bo
~o~ o
Example 5
By replacing the sodium salt in Example 1 with an
equivalent amount of the sodium salt of the ~-lactone of 2-hydroxy-
4,5-epoxycyclopentane-formylacetic acid and following a similar
procedure as in Example 1, there is thus obtained the compound
of formula IV (R=CH3; X=single bond; Y=O) having the formula:
r-f
~ CH - o ~ ~
~0 0
Example 6
By replaci.ng the sodium salt in Example 1 with an
equivalent amount of the sodium salt of the ~-lactone of 2-hydroxy-
cyclopentane-formylacetic acid and the 3-methyl-chlorobutenolide by
an equivalent amount of chlorobutenolide and following the
similar procedure as in Example 1, there is thus obtained the
compound of the formula IV (R=H; X=single bond; Y=2H) having the
formula:
r-s
r¦~CH - O J~ o,~
O O
Example 7
By replacing the sodium salt in Example 1 with an
equivalent amount of the sodium salt of 3-hydroxymethylene-1,4-
butyrolactone and the 3-methyl-chlorobutenolide by an equivalent
amount of chlorobutenolide and following a similar procedure as
in Example 1, there is thus obtained the compound of -the
formula IV (R=H; A and B=H; X=single bond) having the formula:
~ CH -o
--8--
