Note: Descriptions are shown in the official language in which they were submitted.
- ~Z34
,
BACKGROUND OF THE INVENTION
.
Field of the Invention
This invention relates to novel thiadiazole derivatives
or acid addition salts thereof, and a process for producing
the same.
Description of the Prior Art
There have heretofore been developed and used a number
of anti-tumor agents for malignant tumors and leukemia. How-
ever, these anti-tumor agents are highly toxic and hence
require especial care, for their actual application, in avoid-
ing any adverse side effects. Another disadvantage is that when
being formulated, such agents encounter much inconveni--
ence due primarily to their relatively poor solubility in
water or other media. Accordingly, the conventional anti-tumor
agents are not necessarily satisfactory.
In order to overcome the a~ove noted disadvantages of the
prior art techniques, a variety of anti-tumor agents have been studied.
In the studies leading to the present invention, it has been
discovered that thiadiazole derivatives and acid addition salts
thereof of a specific class can achieve the desired and satisfac-
tory results.
SUMMP~RY OF THE INVENTION
One object of the present invention is to provide novel
thiadiazole derivatives or acid addition salts thereof which
are substantiallydevoid of the defects of the existing anti-
tumor agents and which possess strong healins effects on
leukemia and malignant tumors.
It is another object of the invention to provide a
process for producing these novel thiadiazole derivatives or
acid addition salts thereof.
,
, . .
~(3Z3~
These and other objects and advantages of the inven-
tion as hereinafter will become readily apparent can be
attained by the discovery of compounds represented by the
formula (I),
Rl N - N
R2-C-CONH ~ S Y (I)
NH2
wherein Rl represents a hydrogen atom, and R2 represents
a lower alkyl group, an aryl group, an aralkyl group,
a lower alkylthio lower alkyl group, a lower alkyl group
substituted by a carboxyl or hydroxyl group, or a 3-
indolylmethyl group, or wherein Rl and R2 define in combina-
tlon an alkylene group, and pharmaceutically acceptable acid
addition salts thereof.
Such derivatives and acid addition salts have been
fcund to have an extremely low degree of toxicity and exhibit
excellent anti-tumor effects on leukemia and malignant tumors
such as sarcoma, cancer and the like. Particularly, the
acid addition salts are desirable because they are readily
soluble in water.
These derivatives and acid addition salts can be
administered by injection (intravenous, subuctaneous and
intramuscular), an oral route and other routes.
DE~ILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The compounds of the formula (I) according to the inven-
tion can be prepared, for example, by reacting 2-amino-1,3,4-
thiadiazole of the formula (III) or a reactive derivative
thereof with an amino acid of the formula (II) or a reactive
derivative thereof, as illustrated by the following reaction
scheme:
-- 2
Z3~
R2-C-COOH + J~ Jl , R2-C-COHN~ S JJ
l~H2 H2N NH2
(II) (III) (I)
wherein Rl and R2 have the same meanings as defined herein-
before.
One starting compound or 2-amino-1,3,4--thiadiazole of
the formula (III) useful in the process of the invention can
be readily prepared in high yields by the method described,
for example, in Chem. Ber. 40, 642 (1907~.
The process of the invention is xeduced to practice us~g
any of the reactions which have been widely utilized in the
field of peptide syntheses.
The amino group of another starting compound or amino
acid of the formula (II) is preferably protected prior to being sub-
ected to a condensation reaction. Examples of the amino-protecting group
include acyl groups such as an acetyl group, a propionyl group,
a benzoyl group, a p-nitrobenzoyl group and the like;
alkyloxycarbonyl groups such as an ethyloxycarbonyl group,
a ter-butyloxycarbonyl group, a ter-amyloxycarbonyl group and
the like; cycloalkyloxycarbonyl groups such as a cyclohexyloxy-
carbonyl group and the like; aralkyloxycarbonyl groups such as
a benzyloxycarbonyl group, a p-methoxybenzyloxycarbonyl group
and the like; aryloxycarbonyl groups such as an o-nitrophenoxy-
carbonyl group and the like; and protecting groups of the
Schiff base type such as a phthaloyl group and a salicylidene
group.
The condensation reaction is conducted by any of the
following methods:
~6~23~
(1) A free N-protected amino acid of the formula (II)
and 2-amino-1,3,4-thiadiazole of the formula (III) are
interacted in the presence of a dehydrating agent or a condens-
ing agent. The dehydrating agent is, for example, N,N'-
dicvclohexylcarbodiimide or the like. The condensing agent is,
for example, a chlorocarbonic ester or a phosphorous ester such
as a dichlorphosphorous diester, a dichlorophosphorous acid
monoester, tetraethyl pyrophosphate or the like.
(2) A reactive derivative of an N-protected amino acid
(II) is reacted with 2-amino-1,3,4-thiadiazole (III). Examples
of the reactive derivative o~ the N-protected amlno acid
include acid chlorides, azides, acid anhydrides, mixed acid
anhydrides, and active esters such as a phenyl ester, a cyanomethyl
ester, an N-hydroxysuccinimide ester, an N-hydroxyphthalimide
ester and the like, and those generally useful in the
syntheses of peptides.
(3) A free N-protected amino acid (II) is reacted with
a reactive derivative of 2-amino-1,3,4-thiadiazole (III). The
reactive derivative includes, for example, an isocyanate or
a phosphazo compound.
In order to carry out the condensation reaction,
approximately equimolar amounts of both starting compounds (II)
and (III) are reacted at temperatures ranging from -70C -
+250C for 1 - 30 hours in the presence or absence of a solvent
under water-free conditions, which may vary depending upon
the type of each of the starting materials to be actually used.
The reaction product can be isolated and purified in the
usual manner known to the art.
The elimination of the amino-protecting group from the
-- 4
3~
resulting condensation product is effected by conventional
techniques. Favorably employed are a catalytic reduction me.hod
in which as a catalyst, use is made of palladiwn, platin~m,
Raney nickel or the like; a reduction method in which liquid
ammonia is used together with either a metallic lithium or a
metallic sodium; and a method in which hydrogen bromide,
hydrogen chloride, hydrogen iodide or the like is reacted in
a solvent such as glacial acetic acid, dioxane, nitromethane,
carbon tetrachloride, diethyl phosphite, ethanol, trifluoro-
acetic acid or the like.
The compounds having the formula (I) of the invention
include the L-, D- and DL-isomers, and particularly desirable
arethe L-lsomersin terms of their pharmaceutical effects.
The compounds of the formula (I) can be converted, in
the known manner, to water-soluble acid addition salts which
are pharmaceutically acceptable. Suitable acids useful in
forming such addition salts include, for example, inorganic
acids such as hydrochloric acid, hydrobromic acid, hydriodic
acid, sulfuric acid, nitric acid, phosphoric acid and the
like; and organic acids such as acetic acid, propionic acid,
dichloroacetic acid, benzilic acid, salycilic acid, oxalic
acid, malonic acid, adipic acid, maleic acid, fumaric acid,
tartaric acid, citric acid, ascorbic acid and the like.
Typical types of compoundsof the formula (I) accord-
ing to the invention were tested to determine the degrees of
their acute toxicity and anti-tumor efficacy with the results
tabulated in Table 1.
5 --
~6~3Z3~
Table 1
¦ Anti-tumor ~est ~ 3)
Te st Acu te D Surviva l
Compounds (1) [LD50 (mg/kg) ] 3i 1- ~t
A >1,600 400 l454
B > 500 200 1464
_
400 157
C >500 200 116
__
D 357 200 157
400 155
E ~1,600 200 143
_ .
400 190
F ~500 200 183
_
400 102
G >S00 200 93
400 124
>1,600 200 121
400 146
I >1,600 200 125
J 165 1 100 153
1 600 119
K ¦>1,600 ¦ 460 116
L ¦1,200 420 ~0143
1 400 156
1,200 1 200 145
3~
(1) Test Compounds
A: 2-DL-Leucylamino-1,3,4-thiadiazole.hydrochloride
B: 2-L-Leucylamino-1,3,4-thiadiazole.hydrochloride
C: 2-D-Leucylamino~1,3,4-thiadiazole.hydrochloride
D: 2-DL-Isoleucylamino-1,3,4-thiadiazole.dihydrochloride
E: 2-DL-Valylamino-1,3,4-thiadiazole.hydrochloride
F: 2-L-Valylamino-1,3,4--thiadiazole.hydrochloride
G: 2-D-Valylamino-1,3,4-thiadiazole.hydrochloride
H: 2-DL-Methionylamino-1,3,4-thiadiazole.hydrochloride
I: 2-DL-Phenylglycylamino-1,3,4-thiadiazole~hydrobromide
J: 2-Cycloleucylamino-1,3,4-thiadiazole.hydrocnloride
K: 2-L-~-Aspartylamino-1,3,4-thiadiazole.monohydrate
~: 2-L-Tryptophylamino-1,3,4-thiadiazole.hydrochloride
M: 2-L-Phenylalanylamino-1,3,4-thiadiazole.hydrobromide
(2) Acute Toxicity
The median lethal dose (LD50) of each of the
test compounds was determined by the Litchfield-Wilcoxon
method after the intraperitoneal injection of the
compound into ddy mice.
(3) Anti-tumor Test
Each experimental group was composed of six CDF
mice. The mice were inoculated intraperitoneally with
106 P388 leukemia, and the test compounds dissolved
in a physiological salt solution were administered
intraperitoneally to the animals 24 hours and 5 days,
respectively, a~ter the inoculation. The survival
effect of each of the compounds was expressed by the
~L6(3~3~
percentage of the survival days of the treated animals
in each group relative to those of the con~rol animals.
Further, the compounds of the invention possess remark-
ably excellent survival effects on the mice inoculated with
L1210 leukemia, Ehrlich carcinoma (solid type) and Crocker
sarcoma.
This invention will now be described in further detail
with reference to certain specific Examples, which are
presented herein for purposes of illustration only and are
not to be construed as limiting unless otherwise specified.
Example 1
(i) 9.6 g of N-benzyloxycarbonyl-DL-leucine and 3.7 g
of triethylamine were dissolved in 150 mQ of chloroform, to
which was added dropwise 3.9 g of ethyl chlorocarbonate
under sodium chloride-ice cooling conditions. The solution
was stirred for 2 hours, to which was then added 3.7 g of
2-amino-1,3,4-thiadiazole, followed by stirring for further
24 hours. The reaction solution was washed with water, and
after drying, the solvent was removed by distillation to
obtain 9.0 g (yield: 71~) of 2-(N-benzyloxycarbonyl-DL-
leucylamino)-1,3,4-thiadiazole as white crystals having a
melting point of 118 - 120C.
(ii) 9.0 g of the thus obtained amino-protected
product was added to a 25% hydrogen bromide-acetic acid, and
the solution was reacted for 2 hours. Thereafter, ether
was added to the reaction solution, and the resulting cry-
stals were collected by filtration to obtain 7.6 g (quanti~
tative, total yield: 71%) of 2-~L-leucylamino-1,3,4-thiadiazole~ -
~ ,s ~6~3~
hydrobr~mide in the form of white crystals having a meltingpoint of 232C (dec.).
(iii) 7.6 g of the hydrobromide was desalted by the
usual method using an ion exchange resin (Amberlite IRA-400),
thereby obtaining 5.0 g of a free base (yield: 9096, total
yiela: 64%) as white crystals having a melting point of 186C
(dec.). 5.0 g of the thus obtained free base was converted
to the corresponding hydrochloride using a 2096 hydrogen
chloride-ethanol solution and then recrystallized from ethanol
to obtain 5.5 g (yield: 85%, total yield: 61%) of 2-DL-
leucylamino-1,3,4-thiadiazole.hydrochloride as colorless
prisms having a melting point of 203C (de.).
Elementary analysis:
C H N
Calculated for CgHlsN4CQOS (%) 38.32 6.03 22.34
Found (%) 38.09 5.8122.38
(iv) N-Benzyloxycarbonyl-L-leucine and N-benzyloxy-
carbonyl-D-leucine were treated in the same manner as in
items ~i), (ii) and (iii) above to obtain 2-L-leucylamino-
1,3,4-thiadiazole and 2-D-leucylamino-1,3,4-thiadiazole,
and acid addition salts thereof.
2-L-Leucylamino-1,3,4-thiadiazole:
Hydrobromide
mp: 213 - 219C (dec.)
[~]D0: +6.79 (C=2.1, EtOH)
- Hydrochloride
mp: 196 - 199C (dec.)
[~]D: +18.0 (C=l.l, MeOH)
_ 9 _
* Trademarlc.
3~
2-D-Leucylamino-1,3,4-thiadiazole:
Hydrobromide
mp: 215 - 219C (dec.)
[~]D -6.25 (C-l.9, EtOH)
Free base
mp: 170 - 176C (dec.)
[~]D : -1.77 (C=0.28, EtOH)
Hydrochloride
mp: 193 - 199C (dec.)
[ ]20 -18.5 (C=l.l, MeOH)
Example 2
(i) 9.6 g of N-benzyloxycarbonyl-DL-isoleuclne, 3.7 g
of triethylamine, 150 mQ of chloroform, 3.9 of ethyl
chlorocarbonate and 3.7 g of 2-amino-1,3,4-thiadiazole
were subjected to a reaction similar to that in Example
l(i) to obtain 10.3 g (yield: 82%) of 2-(N-benzyloxycarbonyl-
DL-isoleucylamino)-1,3,4-thiadiazole as white crystals having
a melting point of 145 - 149C.
(ii) 10.3 g of the thus obtained amino-protected
product was reacted with a 25% hydrogen bromide-acetic acid
solution in a manner similar -to that in Example l(ii) to
obtain 8.7 g of 2-DL-isoleucylamino-1,3,4-thiadiazole.
hydrobromide (quantitative, total yield: 81%) as white
crystals having a melting point of 236C (dec.).
(iii) The product was desalted in a manner similar to
that in Example l(iii) to obtain 5.3 g (yield: 84%, total
yield: 68%) of a free base as white crystals having a melting
-- 10 --
Z34
point of 99 - 100C (dec.) Further, the corresponding
hydrochloride was prepared in the same manner as in Example 1
(iii) and recrystallized from ethanol to obtain 6.4 g (yield:
75%, total yield: 62%) of 2-DL-isoleucylamino-1,3,4-
thiadiazole.dihydrochloride as colorless prisms having a
melting point of 198C (dec~).
Elementary analysis:
C H N CQ
Calculated for CgH16N4CQ2OS ~%) 33.45 5.61 19.51 24.69
Found (%) 33.76 5.41 19.79 24.41
Example 3
(i) 26.5 g of N-benzyloxycarbonyl-DL-leucine and 10 g
of 2-amino-1,3,4-thiadiazole were dissolved in 80 mQ of
lioxane, to which was added dropwise 2Q mQ of a dioxane solu-
tion of 20.6 g of N,N'-dicyclohexylcarbodiimide, followed by
_~irring at room temperature for 24 hours. The solvent was
removed from the reaction solution by distillation under
reduced pressure, and the residue was recrystallized from
diluted ethanol to obtain 20.9 g (yield: 56%) of 2-(N-
~enzyloxycarbonyl-DL-leucylamino)-1,3,4-thiadiazole as color-
less crystals having a melting point oE 1~1C (dec.).
(ii) 20.9 g of the condensate obtained in item (i)
above was catalytically reduced in 200 mQ of ethanol in the
presence of palladium chloride, and separated and purified in
the usual manner to obtain 13 g (quantitative, total yield:
56%) of 2-DL-leucylamino-1,3,4-thiadiazole as colorless
crystals having a meltins point of 186~C (dec.~.
~3~
Example _
(i) 26.5 g of N-benzyloxycarbonyl-DI,-isoleucine and
10 g of 2-amino-1,3,4-thiadiazole were reacted in the same
manner as in Example 3(i) to obtain 19.5 g (yield: 56%) of
2-(N-benzyloxycarbonyl-DL-isoleuCylamino)-1,3,4-thiadiazole
as white crystals having a melting point of 149C.
(ii) 19.5 g of the thus obtained N-protected product
was reacted in the same manner as in Example l~ii) to obtain
12.0 g (quantitative, total yield: 56%) of 2-DL-isoleucy-
lamino-1,3,4-thiadiazole as colorless crystals having a
melting point of 99 - 100C (dec.).
Example 5
(i) 10 g of N-benzyloxycarbonyl-DL-phenylglycine,
3.6 g of triethylamine, 150 m~ of chloroform, 3.8 g of ethyl
chlorocarbonate and 3.6 g of 2-amino~1,3,4-thiadiazole were
reacted in the same manner as in Example l(i) to obtain 8.2 g
(yield: 63~) of 2-(N-benzyloxycarbonyl-DL-phenylglycylamino)-
1,3,4-thiaaiazole as white crystals having a melting point
of 172 - 174C.
(ii) 8.2 g of the thus obtained amino-protected
product was treated with a 25~ hydrogen bromide-acetlc acid `
solution and recrystallized from water to obtain 7.0 g (quanti-
tative, total yield: 63~) of 2-~L-phenylglycylamino-1,3,4-
thiadiazole.hydrobromide as colorless prisms having a meltlng
point of 239C (dec.).
J,' i
-
323~
Elementary analysis:
C H N
Calculated for ClOHllN4OSBr (%) 38.11 3.52 17.7~
Found (%) 38.40 3.48 17.97
(iii~ The hydrobromide was desalted to obtain a free
base as white crystals having a melting point of 160C (dec.).
Example 6
(i) 9.5 g of N-benzyloxycarbonyl-DL-methionine, 3.4 g
of triethylamine, 150 mQ of chloroform, 3.7 g of ethyl
chlorocarbonate and 3.4 g of 2-amino-1,3,4-thiadiazole were
reacted in the same manner as in Example l(i) to obtain 10.3 g
(yield: 84%) of 2-(N-benzyloxycarbonyl-DL-methionylamino)-
1,3,4-thiadiazole as white crystals having a melting point
of 155 - 159C.
~ ii) 10.3 g of the thus obtained amino-protected
product was suspended in anisole, to which were added 7 mQ
of methyl ethyl sulfide and a 25~ hydrogen bromide-acetic
acid solution, followed by reaction at room temperature for
1 hour. The reaction solution was treated in the usual
manner to obtain 8.8 g (quantitative, total yieId: 84%) of
2-DL-methionylamino-1,3,4-thiadiazole.hydrobromide as white
crystals having a melting point of 207C (dec~).
(iii) The thus obtained hydrobromide was desalted
using Amberlite IRA-400 to obtain 6.1 g (yield: 94~, total
yield: 78%) of a free base as white crystals having a melting
point of 150 - 153C (dec.).
* Trademark.
- 13 -
~.
Z3~L
(iv) The f~ee base was treated with a 20% hydrochloric
acid-ethanol solution and recrystallized from ethanol to
obtain 5.4 g ~yield: 76%, total yield: 60%) of a hydrochloride
as colorless flakes having a melting point of 193 - 194C
(dec.).
Elementary analysis:
C ~ N
Calculated for C7H13N4OS2CQ (%) 31.28 4.87 20.84
Found (%) 31.68 4.82 20.96
Example 7
(i) 10 g of N-benzyloxycarbonylcycloleucine, 3.9 g of
triethylamine, 150 mQ of chloroform, 4.1 g of ethyl
chlorocarbonate and 3.9 g of 2-amino-1,3,4-thiadiaæole were
reacted in the same manner as in Example l(i) to obtain 8.4 g
(yield: 64%) of 2-(N-benzyloxycarbonyl-cycloleucylamino)-1,3,4-
thiadiazole as white crystals having a melting point of 229 -
233C.
(ii) 8.4 g of the thus obtained amino-protected product
was reacted with a 25% hydrobromic acid-acetic acid solution
at room temperature for 2 hours and treated in the usual
manner to obtain 7.1 g (quantitative, total yield: 64%) of
2-cycloleucylamino-1,3,4-thiadiazole.hydrobromlde as white
crystals having a melting point of 230C (dec.).
(iii) To the aqueous solution of the hydrobromide was
added sodium hydroxide to render it alkaline, followed by
treatment in the usual manner to obtain 4.5 g (yield: 88%r
total yield: 56%) of a free base as white crystals having a
melting point of 125 - 127C (dec.).
- 14 -
Z3~
(iv) The free base was treated with an equimolar amount
of concentrated hydrochloric acid and recrystallized from
ethanol to obtain 4.9 g (yield: 91%, total yield: 51~) of
a hydrochloride as colorless prisms having a melting point
of 199C (dec.).
Elementary analysis: C H N
Calculated for C8H13N4OSC~ (%) 38-63 5.27 22-53
Found (%) 38.48 5.31 22.14
Example 8
(i) 10 g of N-benzyloxycarbonyl-DL-valine, 4.1 g of
triethylamine, 150 mQ of chloroform, 4.4 g of ethyl
chlorocarbonate and 4.1 g of 2-amino-1,3,4-thiadiaæole were
reacted in the same manner as in Example l(i) to obtain 10.5 g
(yield: 79%) of 2-(N-benzyloxycarbonyl-DL-valylamino)-1,3,4-
thiadiazole as white crystals having amelting point of
162 - 164C~
(ii) 10.5 g of the thus obtained amino-protected
product was treated with a 25% hydrobromic acid-acetic acid
solution to obtain 8.8 g (quantitative, total yield: 79%) of
2-DL-valylamino-1,3,4-thiadiazole.hydrobromide as white
crystals having a melting point of 236C (dec.).
(iii) The hydrobromide was desalted using Amberlite
IRA-400 to obtain 5.4 g (yield: 86%, total yield: 68%) of a
free base as white crystals having a melting point of 104 -
106C (dec.).
(iv) The free acid obtained in item (iii) above was
treated with an equimolar amount of concentra~ed hydrochloric
%:3~
acid and recrystallized from ethanol to obtain 5.9 g (yield:
93%, total yield: 63%) of a hydrochloride as colorless
prisms having a melting point of 218C (dec.).
Elementary analysis:
C H N
Calculated for C7H13N4OSCQ (%) 35.52 5.54 23.67
Found (%) 35.79 5.46 23.53
~ v~ N-Benzyloxycarbonyl-L-valine and N-benzyloxycarbonyl-
D-valine were treated in the same manner as in items (i) to
(iv) above to obtain 2-L-valylamino-1,3,4-thiadiazole and
2-D-valylamino-1,3,4-thiadiazole,and acid addition salts
thereof.
2-L-Valylamino-1,3,4-thiadiazole:
Hydrobromide
mp: 229 - 230C (dec.)
[~]D : +21.6 (C=1.3, MeOH)
Free base
mp: 125 - 126C (dec.)
[a]D +16.5 (C=1.3, MeOH)
Hydrochloride
mp: 203 - 204C (dec.)
[~]D0 +35 0O (C=1.0, MeOH~
2-D-Valylamino-1,3,4-thiadiazole:
Hydrobromide
mp: 222 - 227C (dec.)
[~]D : -19.7 (C=1.4, MPOH)
- 16 -
~ 23~
Free base
mp: 126 - 1~8C (dec.)
[a]20 -4.55 (C=l.l, MeOH)
Hydrochloride
mp: 199 - 200C ~dec.)
[~]D ~35 5 (C=l.l, MeOH)
Example 9
~ i) Using the same procedure as in Example l(i), 10 g
of a ~-~enzyl ester of N-t-butoxycarbonyl-L-asparatic acid,
3.1 g of triethylamine, 3.4 g of ethyl chlorocarbonate and
3~1 g of 2-amino-1,3,4-thiadiazole were reacted ïn 100 m~ of
chloroform to obtain 8.1 g (yield: 64~) of a ~-benzyl ester
of 2-tN--t-butoxycarbonyl-L-~-aspartylamino)-1,3,4-thiadiazole
as white crystals of mp: 112 - 1]4C and [~]20: -30.0 (C=1.0,
MeOH).
(ii) 8.1 g of the resul-ting condensation product was
treated with an alkali at room temperature for 1 hour to
obtain 5.9 g (yield: 93%) of 2~(N-t-butoxycarbonyl-L-~-
aspartylamino)-1,3,4-thiadiazole as white powder of mp: 120 -
128C ~dec.) and [~]D : -40.8 (C=l.l, MeOH).
(iii) 5.9 g of the thus obtained amino-protected
product was treated with a dioxane solution of hydrogen chloride
at room temperature for 2 hours to remove the amino-protect-
ing group. A crude hydrochloride of mp: 150 - 154C (dec.)
and [~]D0: +7.4 (C=1.0, MeOH) was obtained (quantitative
yield: 4.7 g). The resulting hydrochloride in the amount of
4.7 g was dissolved in water and neutralized with an alkali,
- 17 -
3~
and the free base was recrystallized from water to obtain 2.9 g
(yield: 66%) of 2-L-a-aspartylamino-1,3,4-thiadiazole.mono-
hydrate as colorless prisms of mp: 151C (dec.) and [~}DO
+31.1 (C=l.0, H2O).
Elementary analysis:
C H N
Calculated for C6HloN4O4S (%) 30.77 4.30 23-92
Found (%) 30.38 4.14 23.66
Example 10
(i) Using the same procedure as in Example l(i), 10 g
of N-t-butoxycarbonyl-DL-threonine, 4.6 g of triethylamine,
5.0 g of ethyl chlorocarbonate and 4.6 g of 2-amino-1,3,4,
thiadiazole were reacted in 150 mQ of tetrahydrofuxan to obtain
10.9 g (yield: 79%) of 2-(N-t-butoxycarbonyl-DL-threonylamino)-
1,3,4-thiadiazole as white powder having a melting point of
165 - 170C (dec.).
(ii) 10.9 g of the thus obtained amino-protected
product was treated with a dioxane solution of hydrogen
chloride at room temperature for 2 hours to remove the amino-
protecting gro~p. The resulting hydrochloride was recrystal-
lized from methanol to obtain 7.5 g (yield: 87%) of 2-DL-
threonylamino-1,3,4-thiadiazole.hydrochloride as colorless
prisms having a melting point of 218C (dec.).
Elementary analysis:
C H N
Calculated for C6HllN4O2SCQ ~%) 30.19 4.64 23.47
Found (%) 30.05 4.67 23.63
- 18 -
%3~
Example 11
(i) Using the same procedure as in Example l(i), 10 g
of N-t-~utoxycarbonyl-L-tryptophan, 3.3 g of triethylamine,
3.5 g of ethyl chlorocarbonate and 3.3 g of 2-amino-1,3,4-
thiadiazole were reacted in 150 mQ of chloroform to obtain
10.7 g (yield: 84~) of 2-(N-t-butoxycarbonyl-L-tryptophanylamino)-
1,3,4-thiadiazole as light yellow powder of mp: 98 - 101~C
(dec.) and [~]D : +41.0 (C=1.0, MeOH).
(ii) 10.7 g of the thus obtained amino-protectèd pro-
duct was treated with a hydrogen chloride-dioxane solution
and then wit~ 2-mercaptoethanol at room temperature for 2
hours to remove the amino-protecting group. The resulting
hydrochloride was recrystallized from methanol to obtain
7.3 g (yield: 82%) of 2-L-tryptophanylamino-1,3,4-thiadiazole.
hydrochloride as pinky prisms of mp: 210C (dec.) and [~]DO
+93.0 (C=1.0, MeOH).
Elementary analysis:
C H N
Calcula ed o C13H14N5O C (%)48. 4.36 1.63
Eound (%) 48.34 4.28 21.70
Example 12
(i~ Using the same procedure as in Example l(i), 10 g
of N-benzyloxycarbonyl-L-phenylalanine, 3.3 g of triethylamine,
3.7 g of ethyl chlorocarbonate and 3.5 g of 2-amino-1,3,4-
thiadiazole were reacted in chloroform to obtain 9.1 g (yield:
71%) of 2-(N-benzyloxycarbonyl-L-phenylalanylamino)-1,3,4-
thiadiazole as white crystals of mp: 78 - 83C and [~]DO
-- .
;23~
+28.0 (C=1.2, MeOH).
(ii) 9.1 g of the thus obtained amino-protected pro-
duct was treated with a 25% hydrogen bromide-acetic acid solu-
tion and reerystallized from methanol to obtain 6.2 g (yield:
79%) of 2~L-phenylalanylamino-1,3,4-thiadiazole.hydrobromide
as colorless prisms of mp: 231C ~dee.) and [a]D : +55.1
(C=1.4, MeOH).
(iii) 2-L-Phenylalanylamino-1,3,4-thiadiazole.hydro-
ehloride:
eolorless prisms
mp: 205 - 206C (dee.)
[ ]20: +86 io (C=1.0, MeOH)
(iv) 2-L-Phenylalanylamino-1,3,4-thiadiazole:
white powder
mp: 133C (dee.)
[a]D : +3S.2 (C=1.2, MeOH)
Having fully deseribed the invention, it will be
apparent to one skilled in this art that many ehanges and
modifications can be made without departing from the spirit
or scope of the appended claims.
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