Note: Descriptions are shown in the official language in which they were submitted.
-- 1 --
4~Aminobutyric acid derivatives and Process for the
~reparation thereof
The present invention relates to novel 4-aminobutyric
acid derivatives and a process for the preparation thereof.
The invention thus provides 4-aminobutyric acid
derivatives of the ~ormula:
CH3
RlCOOCH2-C - CH-CONH(cH2)3cOOH (I)
C 3 OH
wherein Rl is a straight or branched alkyl group having
1 to 8 carbon atoms, or a pharmaceutically acceptable salt
theref.
It is known that calcium hopanthenate [chemical name:
calcium D-(~)-(2,4-dihydroxy-3,3-dimethylbutyramido)
butyrate] relieves various s~mptoms such as hyperactivity,
short attention span, speech disorders, hypobulia, etc.
which accompany mild mental retardation, postencephalitic
syndrome, cerebral palsy, etc. and hence is useful as a
reme~y for the amelioration of cerebral metabolism and
higher brain unction disorder.
Based on the knowledge that when calcium hopanthenate
is administered orally, it is present in vivo (e.g. in
blood plasma and brain) in the form of free hopanthenic
acid, the present inventors have investigated various
analogous compounds. As a result, it has been found
that the novel compounds of the above formula (I~ when
~3LZ~97
administer~d orally are absorbed well and show higher
levels of bioavailability or longer duration of action
in th~ blood and brain than calcium hopanthenate. Hence,
they are useful as medicines for the amelioration of
cerebral metabolism and higher brain function disorders.
Specific examples of the compounds of the invention
are the compounds of the formula (I) wherein Rl is a
straiyht or branched alkyl group having 1 to 8 carbon
atoms, such as methyl, ethyl, n-propyl, isopropyl, n-butyl,
isobutyl, sec.-butyl, tert.-butyl, n-pentyl, isopentyl,
sec.-pentyl, tert.-pentyl, 2,2-dimethylpropyl, l-ethyl-
p~opyl, n-hexyl, n-heptyl, n-octyl, or the like. Suitable
examples are the compounds of the formula (I) wherein Rl
is a branched alkyl group having 3 to 5 carbon atoms, such
as isopropyl, isobutyl, isopentyl, tert.-butyl, 2,2-di-
methylpropyl, or l-ethylpropyl group. Particularly prefer-
able compounds are D-4-[N-(4-isobutyryloxy-3,3-dimethyl-2-
hydroxy-n-butyryl)amino]-n-butyric acid and D-4-1N-(4-iso-
valeroxyloxy-3,3-dimethyl-2-hydroxy-n-butyryl)-amino]-n-
butyric acid. These compounds advantageously can be
obtained in crystalline form.
The compounds (I) of the present invention can be
prepared by the following processes:
A) subjecting a 4-aminobutyric acid ester of the
formula:
IH3
RlCOOCH2-C - CH-CONH(CH2)3COOR2 (II)
c~3 OH
. .. ~ ~, 1
. 3
wherein Rl is as defined above, and R2 is a group
removable by a catalytic reduction (e.g. benzyl, p-methoxy-
benzyl, p-chlorobenzyl, or p-nitrobenzyl group), to a
catalytic reduction; or
B) reacting a 4-aminobutyric acid derivative of the
formula:
~H3
HOCH2-C - CH-CONH (CH2) 3COOH (III)
CH3 OH
wlth a reactive derivative of a carboxylic acid of the
formula:
RlCOOH (IV)
wherein Rl is as defined above.
The procedure of the above processes is explained in
more detail below.
Process A
.
The startin~ compound (II) is catalytically reduced in
an appropriate solvent in the presence of a catalyst while
introducing hydrogen gas into the reaction system. The
catalyst may be, for example, palladium black or palladium-
carbon. The solvent may be, for example, a lower alkanol
(e.g. methanol, ethanol, n-propanol, isopropanol), tetra-
hydrofuran, dioxane, or a mixture of these solvents with
water. The above reaction is usually caried out at a
temperature of 0 to 60C under 1 to 10 atm~, preferably
at a temperature of 10 to 30C under 1 to 3 atm.
--4--
Process B
The starting compound ~III) and the reactive derivative
of the compound (IV) are reacted in an appropriate solvent
in the presence of a base. The compound (III) may be used
in the form of ~ salt (e.g. the calcium salt thereof)~ The
reactive derivative of the compound (IV) may be any conven-
tional derivative, preferably an acid anhydride or acid
halide thereof. The base may be, for example, an alkali
metal hydroxide (e.g. sodium hydroxide, potassium hydrox-
ide~ an alkali metal carbonate (e.g. sodium carbonate,
potassium ~arbonate3; an alkali metal bicarbonate (e~g.
sodium bicarbonate, pot~ssium bicarbonate), an organic ker-
tiary amine (e.g. triethylamine, pyridine, dimethylaniline,
p-dimethylaminopyridine~, or the like. The solvent may be9
for example, tetrahydrofuran, dioxane, chloroform, methyl-
ene chloride, benzene7 ethyl acetate~ dimethylformamide,
diethyl ether, water, or the like, which may be used alone
or as a mixture thereofO The above reaction is usually
carried out at a temperature of -15 to 50C, preferably
0 to 20C.
The compounds (I) of the present invention contain one
asymmetric carbon within the molecule and hence include two
optical isomers. The present invention includes these
isomers individually as well as their racemic mixture. Of
these isomers, the compounds wherein the asymmetric carbon
has D-configuration are particularly preferable for
medical use.
~Z19S~7
The starting compound (II) used in the above process
is also novel and can be prepared by the following process.
A 4-aminobutyric acid ester of the formula:
l~3
HOC~-C - CH-CONH(CH2)3COOR2 ~V)
CH3 OH
wherein R2 is as defined above, is reacted with a
reactive derivative of a carboxylic acid of the formula:
RlCOO~ (IV)
wherein Rl is as deEined above.
The reaction of the compound (V) and the reactive
derivatlve of a carboxylic acid (IV) is preferably carried
out in an appropriate solvent (e.g. tetrahydrofuran,
dioxane, chloroform, methylene chloride, benzene, ethyl
acetate, dimethylformamide, diethyl ether, methyl ethyl
ether, water, or a mixture thereof) in the presence or
absence of a base (e.g. an organic tertiary amine such as
triethylamine, pyridine, dimethylaniline, or p-dimethyl-
aminopyridine; or an inorganic base such as sodium
hydroxide, potassium hydroxide, sodium carbonate,
potassium carbonate, sodium bicarbonate, or potassium
bicarbonate) at a temperature of -lS to 50C.
The compound (V) can be prepared by reacting a metal
salt or organic amine salt of ~-[N-(2,4-di-hydroxy-3,
3-dimethyl-n-butyryl)amino]-n-butyric acid with a compound
of the formula: R X (wherein R2 is as defined above,
and X is a halogen atom, e.g. a chlorine, bromine or
~,
-- 6 --
iodine atom), or by reacting a 4-amino-n-butyric acid
ester of the formula:
H2N~ 2)3CR2 (VI)
wherein R2 is as defined above, with a Y-lactone of
2,4-dihydroxy-3,3-dimethyl-n-butyric acid.
The compounds (I) of the present invention may be used
in the form of a free acid or in the form of a pharma-
ceutically acceptable salt thereof. Suitable examples of
the salt are, for example, the calcium salt, sodium salt,
potassium salt, lithium salt, magnesium salt, lysine salt,
ornithine salt, or arginine salt.
The compounds (I) or a pharmaceutically acceptable
salt thereof is preferably administered by the oral route
(but may also be administered by the parenteral route) as
a conventional preparation, for example, solid preparations
such as tablets f pills ~ powders, capsules, or granules,
and liquid preparations such as solutions, suspensions, or
emulsions. Such preparations can be prepared in a conven-
tional manner, for example, by admixing a compound of the
formula (I) or a pharmaceutically acceptable salt thereof
with a conventional carrier or diluent, e.g. calcium
carbonate, calcium phosphate, corn starch, potato starch,
lactose, talc, and magnesium stearate.
The dose of the compound (I) or a pharmaceutically
acceptable salt thereof may vary in accordance with the
kind of disease to be treated, the age and weight of the
patient, the severity of disease and the administration
5~37
-- 7 --
routes, but is usually in the range of 1 to 20 mg/kg/day,
preferably 2 to 10 mg/kg/day, for oral administration.
When the compound (I) or a pharmaceutically acceptable
salt thereof of the present invention is administered,
they can be detected in high levels in the blood and
brain, as confirmed by the following in vivo experiments.
Experiment 1
5D-male rats, weighing about 200 g, 7 weeks of age,
having been fasted overnight (one group: 4 rats) were used.
A suspension (2 ml) of a test compound in a 0.5 ~ carboxy-
methyl cellulose solution was orally administered to each
rat with a stomach sonde (dose of test compound: 389.4
llmole/kg, corresponding to 100 mg/kg of calcium hopanthen-
ate). One or two hours after the administration, the rats
were killed by cutting their carotid arteries, and the
blood was collected. The blood of each rat was centrifuged
(2,800 r.p~m., 15 minutes) to separate the blood plasma.
The concentration of hopanthenic acid in the blood plasma
(0.1 ml) was measured by gas chromatography and mass
spectrometry. The results are shown in Table 1.
Table 1
_
Level of hopanthenic acid in the
Compound blood plasma (~g/ml)
No. (average ~ S.D.)
One hour after the Two hours after the
administration administration
1 32.9 + 2.7 1~.4 + 3.5
2 37.3 + 1.8 21.3 + 1.8
Control 19.4 ~ 1~9 14.2 + 1.6
s~
- 8
[Remarks]:
Compound No. 1: D-4-[N-Isobutyryloxy-3,3~dimethyl-2-
hydroxy-n-butyryl)amino]-n-butyric acid
Compound No. 2: D-4-[N-(4-Isovaleryloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric
acid
Control: Calcium D-4-1N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate
Experi_ent 2
SD-male rats, weighing about 200 g, 7 weeks of age,
having been fasted overnight, (one group: 4 ra~s) were
used. A suspension (2 ml) of a test compound in a 0.5 %
carboxymethyl cellulose solu~ion was orally administered
to each rat with a stomach sonde (dose of test compound:
389.4 ~mole/kg, corresponding to 100 mg/kg of calcium
hopanthenate). ~wo or three hours after the administra-
tion, the ~erebrum was taken out and washed with physio-
logical saline solution. To the cerebrum was added 9
times its volume of water, and the mixture wa~ homogen-
ized with a homogenizer for one minute under ice-cooling
and then centrifuged at lOrOOO r.p.m. at 4C for one hour.
The concentration of hopanthenic acid in the supernatant
(1 ml, corresponding to 0.1 9 of the cerebrum) was measured
by gas chromatography and mass spectrometry. The results
are shown in Table 2. The test compounds were the same as
used in Experiment 1.
t
L95~7
Table 2
. __ _____ _ ~
Level of hopanthenic acid in the
Compound cerebrum (~g/g)
No. (average ~ S.D.~
Two hours after the Three hours after the
. ~ administration administration
1 1.57 ~ 0.25 0.63 ~ 0.13
2 1.42 ~ 0.32 0.56 ~ 0.07
Control 0.~ 0.]7 ~ 0,0~
It is clear from the above experimental results that,
when administered orally to rats in a dose o~ 389.4 ~mole/
kg, the compounds of the present invention: D-4-~N-(4-iso-
butyryloxy-3,3-dimethyl-2-hydroxy-n-butyryl]-n-butyric
acid and D-4-lN-(4-isovaleryloxy-3,3-dimethyl-2-hydroxy-
n-butyryl)amino]-n-butyric acid showed a high blood plasma
level of hopanthenic acid that is about 1.2 to 1.9 times
higher than the level resulting from the administration
of calcium hopanthenate, and also showed a high cerebrum
level of hopanthenic acid that is about 1.5 to 2.2 times
higher than the level obtained by administering calcium
hopanthenate.
2Q ~esides, the compounds (I) of the present invention
have low toxicity and hence have high safety. For
instance, the compounds o~ the present invention: D-4-[N-
(4-isobutyryloxy-3,3-dimethyl-2-hydroxy-n-butyryl)amino]-
n-butyric acid and D-4-[N-(4-isovaleryloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric acid showed a maximum
~.i
5~7
10 --
tolerance of above 2,000 mg/kg in mice (said maximum
tolerance was measured by administer ing the test compound
to mice and observing the deaths of the mice 48 hours
after the administration; the maximum tolerance meaning the
dose just less than the dose inducing death of the mice).
Thus, the compounds of ~he present invention are con-
verted into hopanthenic acid _ vivo when administered and
sbow higher levels of hopanthenic acid in the blood and
brain in comparison with calcium hopanthenate with high
safety, and hence, are useful as medicines for the amelior-
ation of cerebral metabolism and higher brain function
disorders.
The present invention is illus~rated by the following
Examples but should not be construed to be limited thereto.
Example 1
(1) Benzyl D-4-[N-2,4-dihydroxy-3,3-dimethyl-n-butyryl)
amino]-n-butyrate (5 g) is dissolved in tetrahydrofuran
(50 ml~, and thereto is added pyridine (3 g). To the
mixture is added dropwi~e with stirring a solution o~
isobutyryl chloride (1.8 9) in tetrahydrofuran (5 ml)
at 0 - 5C. The mixture is stirred at room temperature
overniqht and concentrated under reduced pressure. The
resulting residue i5 dissolved in ethyl acetate, and the
solution is washed with dilute hydrochloric acid, water,
aqueous sodium bicarbonate solution
.~
~Z3L~S~7
and saturated saline solution in order. The ethyl acetate
solution is dried and concentrated under reduced pressure
to remove the solvent. The residue is purified by silica
gel c~romatography (solvent; chloroform : ethyl acetate =
4 : 1) to give benzyl D-4-[N-(4-isobutyryloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyrate (3.6 g, 59.2 %) as a
colorless viscous oil.
IR ~ fllm (cm ): 3350, 1730, 1650, Mass (m/e): 393 (M )
(2) Benzyl D-4-[N-isobutyryloxy-3,3-dimethyl-2-
hydroxy-n-butyryl)amino]-n-butyrate (3.4 g) is dissolved
in methanol (34 ml), and thereto is added palladium black
(30 mg). The mixture is subjected to catalytic reduction
at room temperature under atmospheric pressure. After the
reaction, the reaction mixture is fil~ered to remove un-
dissolved substances, and the filtrate is concentrated
under reduced pressure. The resi~ue is recyrstallized
from ethyl acetate-n-hexane to give D-4-[N-(4-isobutyry-
loxy-3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyric
acid (2.0 g, 76.3 %) as colorless prisms. M.p. 73 - 75C,
IR v nu~ol (cm 1): 3320, 1715, 1610, Mass (m/e): 303
(M ), [~ D6 ~37.2 (c=l, ethanol). Repeated recrys-
tallization of this product from a mixture of ethyl
acetate and isopropyl ether gives colorless prisms melting
at 82 - 83.5C. [~]22 + 37 4O (c=l, ethanol).
(3) D-4-[N-(4-isobutyryloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric acid ~1.0 g) is
dissolved in ethanol (20 ml) and thereto are added
calcium hydroxide (0.15 g) and water (2 ml). The mixture
~LZ~5~7
- 12 -
is stirred at room tem~erature ~or about 40 minutes.
The reaction mixture is filtered to remove undissolved
substances and the filtrate is concentrated under
reduced pressure. The residue is treated with n-hexane
to give calcium D-4- 1N- (4-isobutyryloxy-3,3-
dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(0.85 g, 80.0 %) as colorless powder. [~
+28.3 (c=l, ethanol)
Exam~le 2
(1) In the same manner as described in
Example 1 (1) using benzyl D-4-~N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate (5.0 g), tetra-
hydrofuran (55 ml), pyridine ~3 g) and isovaleryl
chloride (2.1 g), there is obtained benzyl D-4-[N-
(4-isovaleryloxy -3,3-dimethyl-2-hydroxy-n-butyryl)-
amir.o]-n-butyrate (4.0 g, 63.5 %) as a colorless
viscous oil. IR vmax (cm ): 3350,
1730, 1650, ~ass (m/e): 407
(2) In the same manner as described in
Exam~le 1 (2) using benzyl D-4-[N-(4-isovaleryloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(3.8 g), methanol (38 ml) and palladium black (30 mg),
there is obtained D-4-[N-(4-isovale~yloxy-3,3-dimethyl-
2-hydroxv-n-butyryl)amino]-n-butyrate (2.1 g, 70.9 ~)
as colorless prisms. M.p. 84 - 86C, IR Z'max (cm ):
3300, 1720, 1610, Mass (m/e): 317 (rl )~ [~]D +34.1
(c=l, ethanol)
* Trade ~ark
- 13 -
(3) In the same manner as described in
Exam~le 1 (3) using D-4~[N-(4-isovaleryloxy-3,3-
dimethyl-2-hydroxy-n-butyryl)amino]-n-butyric acid
(1.0 g), ethanol (20 ml), calcium hydroxide (0.13 g)
and water (2 ml), there is obtained calcium D-4-
[N-(4-isovaleryloxy -3,3-dimethyl-2-hydroxy-n-
butyryl)amino]-n-butyrate (0.84 g, 79.2 %) as a
colorless powder. ~C~21 +26.1 (c=l, ethanol)
Exam~le 3
(1) In the same manner as described in
Example 1 (1) using benzyl D-4-~N-(2,4-dihydroxy-
3,3-dimethyl-n-butyryl)amino]-n-butyrate (5.0 g),
tetrahydrofuran (55 ml), pyridine (3 g) and iso-
hexanoyl chloride (2.3 g), there is obtained benzyl
D-4-[N-(4-isohexanoyloxy-3,3-dimethyl-2-hydroxy-
n~butyryl)amino]-n-butyrate (4.~ g, 73.1 ~) as a
colorless viscous oil. IRV nU~l*(Cm-l~
3350, 1730, 1650, Mass (m/e): 421 (M )
(2) In the same manner as described in
Example 1 (2) using benzyl D-4-~N-(4-isohexanoyloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(4.0 g), methanol (40 ml) and palladium black (40 mg),
there is obtained D-4-[N-(4-isohexanoyloxy-3,3-dimethyl-
2-hydroxy-n-butyr~l)amino]-n-butyric acid (2.9 g, 92.2 ~)
as a colorless viscous oil. IR~JmaXm (cm 1):
3330, 1720, 1610, ~ass ~m/e): 331 (M ), [~]D6 +31.6
(c=l, ethanol)
* Trade Mark
~. ~
9~
- 14 -
Example 4
(1) In the same manner as described in
Example 1 (1) using benzyl D-4-~N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate (4.0 g), tetra~
hydrofuran (45 ml), pyridine (2.4 g) and pivaloyl
chloride ~1.8 g), there is obtained benzyl D-4-[N-(4-
pivaloyloxy-3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-
butyrate (3.0 g, 47.6 %) as a colorless viscous oil.
IR vmaxm(cm 1): 3350, 1730, 1650, Mass (m/e): 407 (M )
(2) In the same manner as described in
Example 1 (2) using benzyl D-4-[N-(4-pivaloyloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(2.3 g), methanol (28 ml) and palladium black (30 mg~,
there is ohtained D-4-[N-(4-pivaloyloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric acid (1.] g, 50.4 %)
as colorless crystals. M.p. 79 - 82C recrystallized
from a mixture of ethyl acetate and n-hexane, IR
(cm 1): 3350, 1730, 1710, 1610, Mass (m/e): 317 (M )
Example 5
(1) In the same manner as described in
Example 1 (1) using benzyl D-4-[N-(2,4-dihydroxy-3,3
dimethyl-n-butyryl)amino]-n-butyrate (4.0 g), tetra-
hydrofuran (45 ml), pyridine (2.4 g) and 3,3-dimethyl-
n-butyryl chloride (2.0 g), there is obtained benzyl
D-4-[N-(4-(3~3-dimethyl-n-butyryl)oxy-3~3-dimethyl-2
hydroxy-n-butyryl)amino]-n-butyrate (3.7 g, 71.0 ~)
as a colorless sticky oily substance. IR ~maxm (cm ):
-~ * Trade Mar~
~5a59~
- 15 -
3350, 1730, 1650, Mass (m/e): 421 (M )
(2) In the same manner as described in
Example 1 (2) using benzyl D-4-[N-(4-(3,3-dimethyl-n-
butyryl)oxy-3,3-dimethyl-2-hydroxy-n-butyryl)amino]-
n-butyrate (3.5 g), methanol (35 ml) and palladium
black ( 40 mg ), there is obtained D-4-[N-(4-(3,3-
dimethyl-n butyryl)oxy-3,3-dimethyl-2-hydroxy-n-butyryl)-
amino]-n-butyric acid (2.2 g, 79.7 %) as colorless
crystals. M.p. 102 - 104C, IR vmaU~l (cm 1): 3340,
10 1735, 1715, 1610, Mass (m/e): 331 (M+), [~]26 +32.0
(c=l, ethanol)
Example 6
. _
(1) In the same manner as described in
Example 1 (1) using benzyl D-4-[N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate (4.0 g), tetra-
hydrofuran (45 ml), pyridine (2.4 g) and 2-ethyl-n-
butyryl chloride (2.0 g), there is obtained benzyl
D-4-[N-(4-(2-ethyl-n-butyryl)oxy-3,3-dimethyl-2-hydroxy-
n-butyryl)amino]-n-butyrate (2.5 g, 47.9 %) as a colorless
20 viscous oil. IR vmaxm (cm 1): 3350, 1730,
1650, Mass (m/e): 421 (~ )
(2) In the same manner as described in
Exam~le 1 (2) using benzyl D-4-[N-(4-(2-ethyl-n-butyryl)-
oxy-3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
25 (2.4 g), methanol (24 ml) and palladium black ~30 mg),
there is obtained D-4-[N-(4-(2-ethyl-n-butyryl)oxy-
n-butyryl)amino]-n-butyric acid (1.7 g, 90.1 %) as
* Trade Mark
9S~7
a colorless viscous oil. IRYmaX (cm ): 3350, 1730,
1710, 1645, Mass (m/e): 331 (M ), [~]19 +25.9
(c=l, ethanol)
(3) In the same manner as described in
5 Example 1 (3) using D- 4- [N- ( 4 - ( 2-ethyl-n-butyryl)oxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyric
acid (1.0 g), ethanol (20 ml), calcium hydroxide
(130 mg) and water (2 ml), there is obtained calcium
D-4-[N-(4-(2-ethyl-n-butyryl)oxy-3,3-dimethyl-2-
10 hydroxy-n-butryl)amino]-n-butyrate (0.81 g, 76.6 %)
as a colorless ~owder. [a]2l +24.7 (c=l, ethanol)
Example 7
Calcium D-4-[N-(2,4-dihydroxy-3,3-dimethyl-
n-butyryl)amino]-n-butyrate hemihydrate (5.2 g) is
dissolved in water (20 ml), and thereto are simul-
taneously added dropwise with stirring lN aqueous
sodium hydroxide (40 ml) and isobutyric anhydride
(6.4 g) under ice-cooling over a period of about 30
minutes, while keeping a pH of the mixture to 8-9.
After the addition, the mixture is stirred at the
same temperature for 40 minutes. The reaction mixture
is washed with ethyl acetate, and the aqueous layer
is made acidic with 10 % hydrochloric acid and then
extracted with ethyl acetate. The extract is washed
with water, dried and then concentrated under reduced
pressure. The residue is recrystallized from ethyl
acetate-n-hexane to give D-4-~N-(4-isobutyryloxy-3,3-
97
dimethyl-2-hydroxy-n-butyryl)amino]-n-butyric acid
(2.3 g, 37.4~) as colorless crystals.
The physicochemical properties of this
product are identical with those of the product
obtained in Example 1 (2).
Example 8
In the same manner as described in Example 7
using calcium D-4-[N-(2,4-dihydroxy-3,3-dimethyl-n-
butyryl)amino-n-butyrate hemihydrate (5.2 g), iso-
valeric anhydride (7.4 g) and lN aqueous sodiumhydroxide (30 ml~, there is obtained D-4-[N-(4-iso-
valeryloxy -3,3-dimethyl-2-hydroxy-n-butyryl)amino]-
n-butyric acid (1.9 g, 29.6 %) as colorless crystals.
The physicochemical properties of this
product are identical with those cf the product ob-
tained in Example 2 (2).
Exam~le 9
. .
(1) Benzyl D-4-[N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate (4.0 g) is
dissolved in tetrahydrofuran (30 ml) and thereto
is added pyridine (2 ml). To the mixture is added
dropwise a solution of acetyl chloride (1.2 g) in
tetrahydrofuran (5 ml) under ice-cooling. The mixture
is stirred at room temperature overnight and then
concentra-ted under reduced pressure. The residue
- is dissolved in ethyl acetate, and the solution is
washed with dilute hydrochloric acid, water, aqueous
sodium bicarbonate and saline solution in order. The
ethyl acetate layer is dried and concentrated under
reduced pressure. The residue is purified by silica
gel chromatography (solvent; chloroform : ethyl acetate
= 4 : 1) to give benzyl D-4-[N-(4-acetoxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyrate (2.3 g, 50.9 %)
as a colorless viscous oil. IR vmax (cm ): 3350,
1730, 1650, Mass (m/e): 365 (M )
(2) Benzyl D-4-[N-(4-acetoxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyrate (2.0 g) is dis-
solved in methanol (20 ml) and thereto is added palladium
black (20 mg). I'he mixture is subjecte~ to catalytic
reduction at room temperature under atmospheric ~ressure.
After the reaction, the reaction mix-ture is filtered
to remove undissolved substances, and the filtrate
is concentrated under reduced pressure to give D-4-
[N-(4-acetoxy-3,3-dimethyl-2-hydroxy-n-butyryl)amino]-
n-butyric acid (1.38 g, 91.6 ~) as a colorless viscous
oil.~ IR ~max (cm ): 3350, 1720, 1640,
Mass (m/e): 275 (M ), [~]D0 +33.1 (c=l, ethanol)
Exam~le 10
(1) In the same manner as described in
Example 9 (1) using benzyl D-4-[N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate (4.0 g), tetra-
hydrofuran (35 ml~, pyridine (2 ml) and propionylchloride (1.4 g), there is obtained benzyl D-4-[N-(4-
propionyloxy-3,3-dimethyl-2-hydroxy-n-butyryl)amino]-
n-butyrate (2.2 g, 46.9 %) as a colorless viscous
oil. IR vmaxm (cm )o 3350, 1730, 1650, r~ass
(m/e): 379 (M )
(2) In the same manner as described in
Example 9 (2) using benzyl D-4-[N-(4-propionyloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(2.0 g), methanol (20 ml) and palladium black (20 mg),
there is obtained D-4-[N-~4-propionyloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric acid (1.46 g, 95.7 %)
as a colorless viscous oil. IR ymaxm (cm ):
3350, 1720, 1640, Mass (m/e): 289 (M ), [~X]D +30.0
(c=l, ethanol)
Example 11
(I) In the same manner as described in
Example 9 (1) using benzyl D-4-[N-(2,4-dihydroxy-
3,3-dimethyl-n-butyryl)amino]-n-butyrate (4.0 g),
tetrahydrofuran (35 ml), pyridine (2 ml) and n-butyryl
chloride (1.6 g), there is obtained benzyl D-4-[N-
(4-n-butyryloxy-3,3-dimethyl-2-hydroxy-n-butyryl)-
amino]-n-butyrate (2.9 g, 59.6 %) as a colorless
viscous oil. IR vmaxm (cm ): 3370, 1730,
1650, Mass (m/e): 393 (M )~ [~]D ~27.6 (c=l, ethanol)
(2) In the same manner as described in
Example 9 (2) using benzyl D-4-[N-(4-n-butyryloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(2.0 g), methanol (20 ml) and palladium black (20 mg),
there is ob-tained D-4-[N-(4-n-butyryloxy-3,3-dimethyl-
- 20 -
2-hydroxy-n-butyryl)amino~-n-butyric acid (1.48 g,
96.0 ~) as a colorless viscous oil. IRv film
(cm 1): 3350, 1720, 1640, Mass (m/e): 303 ~M )~
[~]D0 +30.2 (c=l, ethanol)
Example 12
(1) In the same manner as described in
Example 9 (1) using benzyl D-4-[N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate (4.0 g), tetra-
hydrofuran (35 ml~, pyridine (2 ml) and n-valeryl-
chloride (1.8 g), there is obtained benzyl D-4-[N-
(4-n-valeryloxy -3,3-dimethyl-2-hydroxy-n-butyryl)-
amino]-n-butyrate (3.0 g, 59.5 %) as a colorless
crystals. M.p. 34 - 35C. IR ~mUaxol(cm 1): 3370, 1730,
1650, Mass (m/e): 407 (M )
(2) In the same manner as described in
~xample 9 ~2) using benzyl D-4-[N-(4-valeryloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(2.6 g), methanol (30 ml) and palladium black (30 mg),
there is obtained D-4-[N-(4-n-valeryloxy -3,3-dimethyl-
20 2-hydroxy-n-butyryl)amino]-n-butyric acid (1.9 g, 93.8 %)
as a colorless viscous oil. IR ~max (cm ):
3350, 1720, 1640, Mass (m/e): 317 (M ), [~]D0 +31.8
(c=l, ethanol)
(3) D-4-[N-(4-Valeryloxy -3,3-dimethyl-2-
hydroxy-n-butyryl)amino]-n-butyric acid (0.9 g) is
dissolved in methanol (10 ml), and thereto is added
L-lysine (0.41 g). The mixture is stirred at room
* Trade Mark
~Z~95~3~
,~
temperature for 30 minutes. ~he reaction mixture is
concentrated under reduced pressure to remove the
solvent. The residue is treated with n-hexane, and
the resulting powder is collecte~ by filtration to
give D-4-[N-(4-valeryloXy -3,3-dimethyl-2-hydroxy-
n-butyryl)amino]-n-butyric acid L-lysine salt (1.13 g,
86.3 %) as a colorless powder. ~.p. 130 - 133C,
~]D +25.5 (c=l, ethanol~
(4) D-4-[N-(4-n-Valeryloxy -3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric acid (1.0 g) is
dissolved in methanol (10 ml), and thereto are added
calcium hydroxide (0.12 g) and water (5 ml). The
mixture is stirred at room temperature and then con-
centrated under reduced pressure. To the residue is
added ethanol, and the mixture is concentrated to
dryness under reduced pressure to give calcium D-4-
[N-(4-n-valeryloxy -3,3-dimethyl-2-hydroxy-n-butyryl)-
amino]-n-butyrate (1.0 g, 94.3 %) as a colorless powder.
ExamPle 13
(1) In the same manner as described in
Example 9 (1) using benzyl D-4-[N-~2,4-dihydroxy-
3,3-dimethyl-n-butyryl)amino]-n-butyrate (4.0 g),
tetrahydrofuran (35 ml), pyridine (2 ml) and n-hexanoyl
chloride (2.0 g), there is obtained benzyl D-4-[N-(4-
n-hexanoyloxy-3,3-dimethyl-2-hydroxy-n-butyryl)amino]-
n-butyrate (3.2 g, 61.4 %) as a colorless viscous
oil. IR7~maX (cm 1): 3370, 1730, 1650, Mass
(m/e): 421 (M )
(2) In the same manner as described in
Example 9 (2) using benzyl D-4- LN- (4-n-hexanoyloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
5 (2.0 g), methanol (20 ml) and palladium black (20 mg),
there is obtained D-4-[N-(4-hexanoyloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric acid (lo 35 g,
~5.9 %) as a colorless viscous oil. IR film
(cm 1): 3350, 1720, 1640, Mass (m/e): 331 (M ), [~]D0
~27.6 (c=l, ethanol)
(3) In the same manner as described in
Example 12 (3) using D-4-[N-(4-n-hexanoyloxy-3,3-
dimethyl-2-hydroxy-n-butyryl)amino]-n-butyric acid
(1.0 g), L-lysine (0.44 g) and methanol (10 ml), there
15 is obtained D-4-[N-(4-n-hexanoyloxy-3,3-dimethyl-2-
hydroxy-n-butyryl)amino]-n-butyric acid L-lysine salt
(1.3 g, 90.2 %) as a colorless powder. M.p. 131 -
134C, [~]D +25.1 (c=0.5, ethanol)
Example 14
(1~ In the same manner as described in
Example 9 (1) using benzyl D-4-[N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate (4.0 g), tetra-
hydrofuran (35 ml), pyridine (2 ml) and n-heptanoyl
chloride (2.2 g), there is obtained benzyl D-4-[N-
(4-n-heptanoyloxy-3,3-dimethyl-2-hydroxy-n-butyryl)-
amino]-n-butyrate (2.5 g, 46.4 %) as a colorless
viscous oil. IR~JmaXm (cm 1): 3370, 1730, 1650,
~ L9~i~37
~.2 ~
r~
Mass (m/e): 435 (M )
(2) In the same manner as described in
Example 9 (2) using benzyl D-4-[N-(4-n-heptanoyloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(1.8 g), methanol (20 ml) and palladium black (20 mg),
there is obtained D-4-[N-(4-n-heptanoyloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino] n-butyric acid (1.3 g, 91.1 %)
as a colorless viscous oil. ~max
3330, 1720, 1640, Mass (m/e): 345 (M )~ [~D3 -~30.2
(c=l, ethanol)
Example 15
(1) In the same manner as described in
Example 9 (1) using benzyl 4-[N-(2,4-dihydroxy-3,3-
dimethyl-n-butyryl)amino]-n-butyrate (4.0 g), tetra-
hydrofuran (35 ml), pyridine (2 ml) and n-octanoyl
chloride (2.4 g), there is obtained benzyl D-4-[N-
(4-n-octanoyloxy-3,3-dimethyl-2-hydroxy-n-butyryl)-
amino]-n-butyrate (2.2 g, 39.6 %) as a colorless
viscous oil. IR ~'max (cm ): 3370, 1730,
1~50, Mass (m/e): 449 (M )
(2) In the same manner as described in
Exam~le 9 (2) using benzyl D-4-[N-(4-n-octanoyloxy-3,3-
dimethyl-2-hydroxy-n-butyryl)amino]-n-bu-tyrate (1.4 g),
methanol (20 ml) and ~alladium black (15 mg), there is
obtained D-4-[N-(4-n-octanoyloxy-3,3,-dimethyl-2-
hydroxy-n-butyryl)amino]-n-butyric acid (1.05 g, 93.8 %)
as a colorless viscous oil. IR~'max (cm ):
5~7
3340, 1710, 1640, Mass (m/e): 359 (M )~ [~]D +27.4
(c=0.5, ethanol)
Example 16
(1) In the same manner as described in
Example 9 (1) using benzyl D-4-[N-(2,4-dihydroxy-3,3-
dime-thyl-n-butyryl)amino]-n-butyrate (4.0 g), tetra-
hydrofuran (35 ml), pyridine (2 ml) and n-nonanoyl
chloride (2.6 y), there is obtained benzyl D-4-[N-(4-
n-nonanoyloxy~3,3-dimethyl-2-hydroxy-n-butyryl)amino]-
n-butyrate (3.9 g, 68.0 %) as a colorless viscous
oil. IR~maX (cm ): 3370, 1735, 1650, Mass
(m/e): 463 (M )
(2) In the same manner as described in
Example 9 (2) using benzyl D-4-[M-(4-n-nonanoyloxy-
3,3-dimethyl-2-hydroxy-n-butyryl)amino]-n-butyrate
(2.0 g), methanol (20 ml) and palladium black (20 mg),
there is obtained D-4-[N-(4-n-nonanoyloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric acid (1.4 g, 86.9 ~)
as a colorless viscous oil. IR ~'max (cm 1):
20 3330, 1720, 1640, Mass (m/e): 373 (M )~ [~]D +26.2
(c=l, ethanol)
(3) In the same manner as described in
Example 12 (3) using D-4-[N-(4-n-nonanoyloxy-3,3-dimethyl-
2-hydroxy-n-butyryl)amino]-n-butyric acid (0.9 g), methanol
(10 ml) and L-lysine (0.35 g), there is obtained D-4-
[N-(4-n-nonanoyloxy-3,3-dimethyl-2-hydroxy-n-butyryl)-
amino]-n-butyric acid L-lysine salt (1.15 g, 91.8 ~)
~J~
as a colorless powder. M.p. 158 - 161C, [~]18 +22.9
(c=0.5, ethanol)
J Reference Exam~le
(1) Calcium D-4-[N-(2,4-dihydroxy-3,3-
5 dimethyl-n-butyryl)amino]-n-butyrate hemihydrate (100 g)
is dissolved in water (500 ml), and the solution is
passed through a column of an acidic type ion-exchange
resin, followed by washing the column with water. The
effluent and washing liquid are eombined and thereto
10 is added dicycl~hexylamine (71 g). The mixture is
washed with ether, and the aqueous layer is concent
rated under reduced pressure. The residue is crystal-
lized from ethyl acetate. The precipitates crystals
are separated by filtration and washed with ether to
give D-4-[N-(2,4-dihydroxy-3,3-dimethyl-n-butyryl)-
amino]-n-butyric acid dicyclohexylamine salt (122 g,
75.6 ~) as colorless crystals.
(2) D-4-[N-(2,4-Dihydroxy-3,3-dimethyl-n-
butyryl)amino]-n-butyric acid dicyclohexylamine salt
(121 g) is mixed with benzyl bromide (50 g) and dimethyl-
formamide (700 ml), and the mixture is stirred at about
60C for 6 hours. The reaction mixture is filtered to
remove undissolved substances and the filtrate is con-
centrated under reduced pressure. The residue is dis-
solved in ethyl acetate, and the solution is washed with
dilute sulfuric acid, saline solution, aqueous sodium
bicarbonate and saline solution in this order. The ethyl
5~
acetate layer is dried and evaporated to dryness under
reduced pressure to give benzyl D-4-[N-(2,4-dihydroxy-
3,3-dimethyl-n-butyryl)amino]-n-butyrate (66 g, 69.9 ~)
as a pale yellow oil. IR Vmax (cm ):
3350, 1725, 1650, Mass (m/e): 323, [~]D +32.0 (c=l,
ethanol)
