Note: Descriptions are shown in the official language in which they were submitted.
- '10~7180
This invention relates to new guanidine derivatives
which possess antiviral properties.
According to the invention there is provided a
guanidine derivative of the formula:-
Rl-NH.C.NH_R2
Il
NH
wherein Rl is a cyclohexyl, adamantyl, bicyclo[2,2,1~heptanyl,
bicyclo[2,2,1]hept-5-enyl, tricyclo[2,2,1,02'6]heptanyl or
tetracyclo[4,3,0,02' ,03'7]nonanyl radical and R2 is a phenyl
or pyridyl radical optionally substituted by 1 or 2 substituents
selected from halogen atoms, alkyl and cyanoalkyl radicals of
1 to 6 carbon atoms, alkoxycarbonyl radicals of 2 to 6 carbon
atoms and amino radicals; and the pharmaceutically-acceptable
acid-addition salts thereof.
The formulae in 3-dimensional representation for
15 adamantyl (II), bicyclo[2,2,1]heptanyl (III), bicyclo[2,2,1]-
hept-5-enyl (IV), tricycylo[?,2,1,0 '6]heptanyl (V) and tetra-
cyclo[4,3,0,02'4,03'7]nonanyl (VI) radicals are as follows:-
~ 2 II
-- 2 --
. . ' ~ ,
.
-
10~7180
3 6 I I I
5¢~ ~ 2 IV
6 2
.
3 VI
1'~17
9\ ' 8
.. . . . . .
.
-
r -
- 10~7180
The point of attachment in radicals II, III, IV, V
or VI may be at any of the numbered positions shown, some of
which are identical to each other, and may be in any one of
the possible stereochemical configurations. For example in
positions 2, 3, 5 or 6 in formula III, positions 5 or 6 in
, formula IV, positions 3 or 5 in formula V and positions 8 or 9
in formula VI, the linkage may have either the exo or endo
configuration, that is it may be cis or trans respectively with
respect to the bridge position (7 in formulae III, IV and V
and 5 in formula VI).
It will be observed that when Rl is a bicyclol2,2,1]-
heptanyl, bicyclo[2,2,1]hept-5-enyl, tricyclol2,2,1,02'6]-
heptanyl or tetracyclo[4,3,0,02'4,03'7]nonanyl radical and themolecule does not contain a plane of symmetry, the guanidine
derivative of the invention will contain an optically-active
centre and may therefore be resolved into two optically-enantio-
meric forms. It is to be understood that in such cases, this
invention encompasses the racemic form and both optically-active
enantiomers of such a derivative.
Particular groups of compounds of the invention
within the above definition are as follows:-
Those wherein Rl is an adamantyl,bicyclol2,2,1]-
heptanyl, bicyclo[2,2,1]hept-5-enyl or tricyclo[2,2,1,02'6]-
heptanyl radical.
Those wherein Rl is a cyclohexyl, adamant-l-yl, exo-
bicyclo[2,2,1]heptan-2-yl, endo-bicyclo[2,2,1]heptan-2-yl, exo-
bicyclo[2,2,1]hept-5-en-2-yl, tricyclol2,2,1,02'6]heptan-3-yl or
-
1087180
tetracyclo[4,3,0,02'4,03'7]nonan-8-yl radical and R2 is a
pyridyl radical or a phenyl radical optionally substituted by
1 or 2 fluorine atoms, by a chlorine or bromine atom, or by a
methyl, cyanomethyl, methoxycarbonyl or amino radical.
Those in which Rl is in the exo-configuration.
Those in which R2 carries one optional substituent.
Those in which Rl is an exo-bicyclo[2,2,1]hept-5-en-2-yl
or exo-bicyclol2,2,1]heptan-2-yl radical and R2 is an optionally
substituted phenyl radical;
Those in which R is an exo-bicyclol2,2,1]hept-5-en-2-yl
radical and R2 is a phenyl radical bearing a single optional
substituent which, for example, may be in the 4-position and may,
for example, be a fluorine, chlorine or bromine atom.
Particular compounds of the invention are described in
the Examples and of those a preferred compound is 2-exo-[3-(~-
chlorophenyl)guanidino]bicyclo[2,2,1]hept-5-ene and the pharma-
ceutically-acceptable acid-additon salts thereof.
A suitable pharmaceutically-acceptable acid-addition
salt of the guanidine derivative of the invention is, for example,
a hydrochloride, phosphate or sulphate or a citrate, acetate,
s~ccinate or fumarate.
The guanidine derivative of the invention may be
manufactured by methods known in themselves for the manufacture
of chemically analogous compounds, for example:-
(a) reaction of a thiourea of the f!ormula:-
Rl-NH.C.NH-R VII
S
. .
5 -
.. ...
. : - ' ' " ' ~ :
~, '
7~80
.
or a thiouronium salt thereof, with ammonia in the presence of
a catalyst;
(b) reaction of a cyanamide of the formula Rl-NHCN or R2-NHCN
with an amine of the formula R2-NH2 or R1-NH2 respectively;
(c) reaction of a carbodi-imide of the formula:-
Rl-N=C=N-R2 VIII
with ammonia; or
(d) for those compounds in which Rl is a cyclohexyl or bicyclo-
[2,2,1]heptanyl radical, reducing a compound of the formula:-
R3-NH.C.NH-R2 IX
I~
NH
in which R3 is cyclohexenyl or bicyclo[2,2,1~heptenyl radical; and
~ ~s~
(e) for a compound which is an optically-active enantiomer,
resolution of the racemic compound of the formula I given
above by conventional means, or by use of any of processes
(a) to (d) above in which the starting material is itself a
resolved isomer.
Process (a) is preferably carried out in a diluent or
~olvent such as ethanol. A preferred catalyst for use in the
process is a heavy metal oxide,for example yellow mercuric oxide
or lead oxide~ and the reaction is preferably conducted at a
temperature between 0C. and 100C. or the boiling point of
the diluent or solvent, whichever is the lower. Use of a
temperature above room temperature may requi.re constant addition
~0~7180
of ammonia in the form of a gas stream. The thiouronium salt
used as an optional starting material may have the formula:-
Rl-NH . C . NH-R X
~S-R4 X ~
in which R is an alkyl radical of 1 to 4 carbon atoms, for
example a methyl radical and X~is an anion, for example a
halide anion such as a chloride, bromide or iodide anion.
Process (b) may be carried out in the presence or
absence of a diluent or solvent at a temperature of between 50
and 250 C., the upper limit being restricted to the boiling
I0 point of the optional diluent or solvent. A suitable optional
diluent or solvent is, for example>n-butanol. The amine
component in the reaction is preferably used in the form of a
salt, for example a hydrochloride.
, Process (c) may be conducted under the same conditions
as process (a), though of course no catalyst is necessary.
Process (d) may be carried out using hydrogen in a
diluent or solvent, for example ethanol, in the presence of a
catalyst, for example a palladium-on-charcoal catalyst, for
example a 5% w/w palladium-on-charcoal catalyst. The hydrogen
may be at atmospheric pressure or at a pressure of up to 5
atmospheres.
The resolution in process (e) may be accomplished, for
example, by fractional crystallisation of a salt of the racemic
derivative of the formula I with an optically-active acid, for
- : ,, '
~087180
example (+)- or (-)- mandelic acid or (+)-0,0-dibenzoyltartaric
acid.
The starting material of the formula VII for use in
process (a) may be obtained by reaction of an amine of the
formula R2-NH2 or Rl-NH2 with an isothiocyanate of the formula
Rl-NCS or R2-NCS respectively. The isothiocyanate itself may
be obtained by reaction of an amine of the formula Rl-NH2 or
R2-NX2 with thiophosgene.
The starting material of the formula Rl-NHCN for
use in process (b) may be obtained by reaction of a compound
of the formula Rl-NCS with ammonia to give the thiourea
R NH.C-NH2
S
which is then reacted with yellow mercuric oxide to give the
required product; or by reaction of an amine of formula Rl-NH2
with cyanogen bromide.
The starting material of the formula VIII for use in
process (c) may be obtained by reaction of the compound of the
formula VII with triphenylphosphine in the presence of carbon
tetrachloride and triethylamine.
The new compounds of the invention possess antiviral
activity, and in particular they are specifically active against
rhinoviruses which, for example, inhabit and multiply in the
upper respiratory tract of warm blooded animals including man.
This activity is demonstrated by a tissue culture assay in human
embryo lung cells whereby it may be shown that the compounds
_ ~ _
~0~7180
inhibit the growth of at least 16 different rhinoviruses at a
concentration which produces no morphological abnormalities on the
tissue culture cells. All the compounds exemplified in this
specification are 50% active against rhinovirus type 2 at or
below a concentration of 5 ~g./ml. whilst producing no morpho-
logical abnormalities in confluent monolayers of tissue culture
cells at a concentration of at least four times the active dose.
Thus, for example, the compound of the invention 2-exo-[3-(p-
fluorophenyl)guanidino]bicyclol2,2,1]hept-5-ene i9 50% active
against rhinovirus type 2 at a concentration of 0.02 ~g./ml.
while it causes 50% of the cells in the tissue culture sheet to
show abnormalities only at a concentration of 25 ~g./ml., a
therapeutic ratio of 1250.
The compound of the invention may be incorporated as
active ingredient into a pharmaceutical composition for the
purpose of treating a rhinovirus infection in warm blooded
; animals. Owing to the highly selective nature of its antiviral
spectrum, the compound of the invention may also be used in
diagnostic studies and in public health laboratories selectively
to inhibit the growth of rhinoviruses whilst allowing other
viruses such as the enteroviruses, the arborviruses, myxoviruses,
and DNA-containing viruses, against which the compound of the
invention has no effeot, to multiply normally in tissue culture.
When used in warm blooded animals to produce the
desired effect, a daily oral dose of from 1 mg./kg. to 15
mg./kg. of a compound of the invention is desirable. When
?
``` 1~87180
- u~ed in man thiæ is equivalent to a daily dose of between
70 mg. and 1 g. In man a daily dose of between 70 mg. and
250 mg. given in divided doses, is preferred. In man a
daily nasal dose of 1 to 125 ~g., and preferably 1 to 25 ~g.,
is desirable.
The compound of the invention may be used in the
form of a pharmaceutical composition which comprises as
active ingredient a guanidine derivative of the invention in
association with a pharmaceutically-acceptable diluent or
carrier therefor.
The pharmaceutical composition of the invention
may be in the form of a conventional tablet, lozenge, capsule,
aqueous or oily solution or suspension, emulsion, nasal drops,
spray, aerosol (either wet, or dry powder) or snuff, and may
be manufactured by conventional techni~ues and incorporate
conventional excipients.
Preferred compositions of the invention are those
which produce a virucidal level of the guanidine derivative
of the invention in those parts of the body where rhinoviruses
; 20 normally grow, for example the mucosa of the nose, throat,
mouth and bronchi, either by direct application of the
composition to those parts or indirectly by producing a
sufficient blood-level of the guanidine derivative after oral
dosing.
Such preferred compositions for direct application
are, for example, lozenges which may be dissolved slowly in
the mouth, in order to bathe the mouth and associated passages
with a solution of the active ingredient, nasal sprays or wet
aerosols in the form of a solution or suspension of the
-- 1 0
10~7180
guanidine derivative in an inert pharmaceutically-acceptable
liquid, or a dry powder aerosol which contains a guanidine
derivative of the invention in finely powdered form, any of
wllich may be inhaled and deposited in the nasal and bronchial
passages, and preferred compositions for oral dosage are,
for example, tablets.
A suitable tablet or lozenge contains from 25 mg.
to 100 mg. of an antiviral compound of the invention, and
the normal regimen for the prophylaxis or treatment of a
rhinoviral infection is one tablet 2 to 4 times per day.
A suitable nasal spray or aerosol contains from 5 ~g.
to 50 ~g. of an antiviral compound of the invention per ml. of -
solution or suspension and for the prophylaxis or treatment of
a rhinoviral infection about O.l ml. of such a solution is
sprayed into the nose by the subject 3 to 6 times per day.
The compositions of the invcntion may also contain
other known pharmaceutically useful compounds, for example
nasal decongestants, antipyretics or antiseptics. Owlng to
the highly selective nature of its antiviral spectrum, the
compound of the invention is also useful in hospital and public
health laboratories for selectively inhibiting rhinovirus growth
in tissue cultures, thus allowing other viruses which may be
present to be detected more easily. For example, clinical
specimens from patents with upper respiratory tract disease
may be cultured in the presence of a compound of the invention.
Rhinoviruses grow in the upper respiratory tract of man, and
rhinoviruses will often be present in such specimens. Rhinovirus
- ~ .
;., ' - ' ' ~
, ~-' . ' . - . ~,~
~' ' ' ''' .
1087180
growth during incubation is prevented but other viruses
which may be present, such as influenza, adenoviruses and
respiratory syncytial virus, grow unchecked. Similarly, in
the public health field, the growth of rhiniviruses may be
suppressed while other viruses such as the enteroviruses, the
arborviruses, myxoviruses, and DNA-containing viruses, against
which the compounds of the invention have no effect, continue
to multiply normally in tissue culture.
As a further alternative~the ability of the compound
of the invention selectively to inhibit the growth of rhino-
viruses in the presence of other viruses provides a diagnostic
tool for the speedy identification of rhinoviruses in a mixed
virus population.
In use the compound of the invention i8 added as
a suspension or solution in a suitable diluent or solvent,
which is generally water or the tissue culture medium, to the
tissue culture under examination. The final concentration of
the compound of the invention may be varied over a wide range,
but is generally in the range of 0.04 to 45 ~g./ml. The
culture is then incubated for the appropriate period of time
at the appropriate temperature before examination for viral
growth.
For example, human embryonic lung cells growing in
Eagle's medium in 4" x ~" glass tubes were doubly infected with
100 TCD50 f herpes simplex type 1 virus and 100 ~CD50 f
rhinoviruses type 2 and incubated at 33C. Two days later,
- ,: ~ .
'
,
~, ,
.
,. . . ,~ ' ~ ~ ,
.. ..
~087180
the cells were seen to be degenerating due to the growth
of the viruses and the culture fluids were shown by infectivity
titrations to contain at least a hundred times more of each
virus than the original inoculum.
In a parallel experiment the culture medium was
prepared containing 2-exo-[3-(p-chlorophenyl)guanidino]bicyclo-
[2,2,1]hept-5-ene at a concentration of 2.5 ug./ml. This
medium was added to doubly infected cell cultures which were
incubated at 33C. for two days, as above. The cells were
then again seen to be degenerating due to virus growth, but
the culture fluids were shown to contain a high concentration
of herpesvirus only, the growth of rhinovirus having been
suppressed.
The invention is illustrated, but not limited, by
the following Examples in which the temperatures are in
degrees Centigrade.
Example 1
A solution of 2-exo-t3-(~-fluorophenyl~thioureidol-
bicyclot2,2,1]hept-5-ene (2 g.) in saturated ethanolic ammonia
(60 ml.) was stirred at room temperature with yellow mercuric
oxide (1.74 g.) for 16 hours. The reaction mixture was
boiled on a steam bath for 15 minutes to drive off excess
ammonia and to congulate the fine precipitate of mercuric
sulphide. This solid was filtered of~, washed with boiling
.
ethanol (10 ml.) twice, and the combined filtrates evaporated
to dryness. The solid residue was recrystallised from ethyl
:
.~
- 13 -
.
,,
,
'' ': '
"
~087180
acetate to giVe 2-exo-[3-(p-fluoropheny~guanidino~ bicyclo-
[2,2,1~hept-5-ene, m.p- 192-194C.
The 2-exo -t3- (~-fluoropheny~thioure ido] b icyc lo-
[2,2,1]hept-5-ene used as starting material may be prepared
a8 follow8:-
A solution of ~-fluoroaniline (2.6 g.) in 25 ml.
chloroform was added to 2-exo-i80thiocyanatobicyclo[2,2,1]-
hept-5-ene (3.0 g.) and the mixtUre 8tirred at room
- temperature for 16 hour8. The mixture was then heated under
reflux for 5 hours to complete the reaction, cooled, and the
801id product filtered off, wa8hed with a little cold chloro-
form and dried. Recrystallisation from toluene gave 2-exo-
t3-(~-fluoropheny~thioureido]bicyclot2,2,1]hept-5-ene, m.p.
201-203C.
` 15 Example 2
The process described in Example 1 wa9 repeated using
appropriately substituted starting materials and the following
compoundswere obtained:-
.
h NH
- 14 -
- : - , . . ~ . . ..
.: ~ : :: - :
- : . ' ~ . :
: .: -
1087180
Rl R2 M.p.
Cl H 206
Br H 214-215
H H 171
F F 187-188*
* Recrystallised from toluene
The starting materials for the aboYe process were
obtained by repeating the process described in the second
part of Example 1 using the appropriately substituted aniline
in place of ~-fluoroaniline as starting material, and cyclo-
hexane in place of chloroform as solvent, and the following
compoundswere obtained:-
.... .
~NHCNII--~ N
R 1 M~P~
Cl 183
. ~r 145
. H 164
~ ' .
- 15 _
~ .... . . .. . .
. . -
-
: :
10~7180
Example 3
A solution of 2-exo-[3-(P-fluoroPhenyl)guanidin
bicyc}o~2,2,1]hept-5-ene (0.5 g.) in ethanol (25 ml.) was
hydrogenated at room temperature and pressure in the presence
of 5% w/w palladium-on-charcoal (0.05 g.) until no more
hydrogen was taken up. The mixture was filtered and the
solvent evaporated in vacuo. The residual solid was re-
crystallised from ethyl acetate to give 2-exo-[3-(p-fluoro-
pheny~guanidino]bicyclo[2,2,1]heptane, m.p. 186.
Example 4
The process described in Example 3 was repeated
uæing the appropriately substituted starting materials and the
following compounds were obtained:-
~ . q ~
~H NH
Rl R2 K p~
~ Cl H 204
i` F F 177
.
~ '
- 16 -
`'
.
.: . : . :
.:
' : : : ~. ' ', ~: - '
- ,
. .
~OB7180
Example 5
A solution of l-(~-fluorophenyl)-3-(2-exo-bicyclo-
[2,2,1]hept-5-enyl)carbodiimide (0.9 g.) in saturated ethanolic
ammonia (10 ml.) was allowed to stand at room temperature for
48 hours. The solvent was evaporated in vacuo from the
suspenæion, and the residual solid was crystallised from
ethyl acetate to give 2-exo-[3-(~-fluorophenyl)guanidino1bicyclo-
[2,2,1]hept-5-ene, m.p. 194.
The l-(~-fluorophenyl)-3-(2-exo-bicycIo[2,2,1]hept-
5-eny~carbodiimide used as starting material was obtained as
follows:-
To a solution of 2-exo-13-(~-fluorophenyl)thioureidol-
bicyclo[2,2,1]hept-5-ene (1.55 g.) in dry methylene chloride
(6 ml.) were added carbon tetrachloride (0.9 g.), triethyl-
amine (0.58 g.) and triphenyl phosphine (1.8 g.). The
mixture was heated to 40. After 20 minutes a clear solution
had formed. After a further 1.5 hours at 40 the solution
was cooled. The solvent was removed by evaporation and the
residue extracted with cold petroleum ether (b.p. 60-80;
3 x 10 ml.). On evaporation of the extract, the required
l-(~-fluorophenyl)-3-(2-exo-bicyclo[2,2,1]hept-5-enyl)carbodi-
imide was obtained as a yellow oil, identified by mass
spectrometry (Mass ion 228) and infra-red spectrometry
(N=C=N very strong absorption at 2100 cm 1), and was used
without further purification.
Example 6
The process described in Example 1 was repeated
- 17 -
,.
:, ' - , : ,
1087180
using 1-(3-p-chlorophenylthioureido)adamantane as starting
material and there was thus obtained 1-[3-(p-chlorophenyl)
guanidin~adamantane, m.p. 196.
The' 1-~3-(p-chloropheny~thioureido]adamantane used
as starting material waæ obtained as follows:-
Separate solutions of l-aminoadamantane (0.9 g.)
and p-chlorophenylisothiocyanate (0.9 g.) in chloroform
(10 ml.) were mixed and stirred at 20 for 3 days. The
solvent was evaporated in vacuo and the residual solid
recrystallised from toluene to give ~[3-(~-chlorophenyl)-
thioureido]adamantane, m.p. 185.
Exam~le 7
The procesæ described in Example 1 was repeated
using appropriately substituted starting materials and the
following compounds were obtained:-
.
e~NH~-NH--~ R
- 18 -
., . , : .
.
.
',
~087180
~l R2 ¦ R3 ¦ m.p. ¦ Footnote
H Cl H 154 1
CH3 H H 208-209 1
: H CH3 H 179-181 2
H H CH3 160-162 2
CH2CN H H 170
COOCH3 H H 199-200
NH2 H H 204-205 3
H NH2 H 158-160 2
Footnotes
.,
.1. Recrystallised from ethyl acetate
. 2. Recrystallised from toluene
'J 5 3. Hydrochloride, recrystallised from isopropanol/ethyl acetate
q:
The starting materials for the above process were
obtained by repeating the process described in the second
part of Example 1 using the appropriately-substituted aniline
as starting material in place of p-fluoroaniline, and cyclo-
hexane in place of chloroform as solvent, and the following
'compounds were obtained:-
.. :
R3 R
.
- - 19 -
- -
.
' ' ' : , ~ ':
.
. ~ , . . .. : :
-
10~7180
~l ~ R~ = Footnote
H Cl H 140-141 1
CH3 H H 173
H CH3 H 125-128 2
H H CH3174-175 3
COOCH3 H H 177-178 3
NH2 H H 158
H N~2 ~ _ 4
Footnotes
1. Recrystallised from toluene
2. Recrystallised from ether
3. Recrystallised from ethyl acetate
4. U~ed without further purification
...... .
Example 8
The process described in Example 1 was repeated
using 2-exo-[3-(4-pyridyl)thioureido]bicyclo[2,2,1]hept-5-ene
hydrochloride in place of the 2-exo-[~(p-fluoropheny~thioureido]-
bicyclo[2,2,1]hept-5-ene. There was thus obtained 2-exo-[3-
(4-pyridyl)guanidino]bicyclo[2,2,1]hept-5-ene which was converted
A cll~or~
to its dihydro~Pdic salt and recrystallised from a mixture
of ethanol and ethyl acetate, giving a product melting at 282
with decomposition.
The starting material was obtained by repeating the
process described in the second part of Example 1 using 4-amino-
- 20 -
,
:. , . ' , . .
, ,
. .
.
. - , '
- ` 101~7180
pyridine in place of p-fluoroaniline and refluxing for 3 days
instead of 5 hours. The product was isolated as its hydro-
chloride salt and had a melting point of 200-201.
Example 9
The process of Example 1 was repeated using 2-endo-
(3-phenylthioureido)bicyclo[2,2,1]heptane as starting material
in place of 2-exo-[3-(p-fluoropheny~thioureido]bicyclo[2,2,1]-
hept-5-ene. There was thus obtained 2-endo-(3-phenylguanidino)-
-~ bicyclo[2,2,1]heptane, m.p. 132-133 on recrystallisation from
toluene.
The starting material may be prepared as follows:-
A solution of 2-endo-aminonorbornane in cyclohexane
(obtained by extraction of an alkaline solution in water of
2-endo-aminonorbornane hydrobromide (1.5 g.) with cyclohexane
followed by drying over anhydrous magnesium sulphate), was
added to a solution of phenylisothiocyanate (1.38 g.) in cyclo-
hexane and stirred for 10 hours at room temperature. The
precipitated product was filtered off, washed with cyclohexane
and then recrystallised from cyclohexane to give 2-endo-(3-
20 phenylthioureido)bicyclo[2,2,1]heptane, m.p. 154.
Example 10
l-Cyclohexyl-3-(p-chlorophenyl~hiourea (2.0 g.) was
dissolved in absolute ethyl alcohol saturated with ammonia
(40 ml.). To this was added yellow mercuric oxide (1.7 g.)
and the mixture stirred at room tempçrature for 16 hours. The
mixture was then refluxed 15 minutes to coagulate the fine
- 21 -
,
10~37180
precipitate Or mercuric sulphide, filtered and the clear
.~iltrate evaporated to dryness. The residue was recrystallised
from toluene to give l-cyclohexyl-3-(p-chlorophenyl)guanidine, m.p.
187-190.
The starting material may be obtained as follows:-
To a solution of cyclohexylamine (1.75 g.) in
chloroform (15 ml.) was added dropwise with stirring a solution
of p-chlorophenylisothiocyanate (3.0 g.) in chloroform (15 ml.)
at room temperature. After stirring 3 hours, the white solid
was filtered off, washed with a little CHC13 and recrystallised
from toluene to give l-cyclohexyl-3-(p-chlorophenyl)thiourea,
m.p. 179-180.
Example 11
To a solution of 3-C3-(P-chlorophenyl)thioureido]tri
15 [2,2,1,02'6]heptane (0.25 g.) in ethanol saturated with ammonia
(10 ml.) was added 0.2 g. of yellow mercuric oxide, and the
mixture stirred at room temperature for 16 hours. The solids
were filtered off and the clear filtrate evaporated to dryness.
The residual solid was recrystallised from toluene to give 3-[3-(~-
20 chloropheny ~uanidino~tricyclo[2,2,1,02'6]heptane, m.p. 204-205.
The thiourea used as starting material may be
prepared as rOllOws:-
3-Aminotricyclo[2,2,1,02'6]heptane (21 g.) (prepared
as described in U.K. Patent Specification 1,051,319), was
dissolved ln chloroform (25 ml.) and added slowly, below 10, to
a stirred solution of thiophosgene (22 g.) in chloroform (20 ml.).
- 22 -
. ,. . , : - -
-
- . ' ' ' ' ~ ' .
.: . .
10~7180
When addition was complete the mixture was allowed to attain
ambient temperature and stirred a further 2 hours. The chloro-
form solution was consecutively washed with 20 ml. portions of
water, lN NaOH, and water again, dried over anhydrous MgS04,
filtered and the chloroform evaporated in vacuo. The residual
oil was fractionally distilled in vacuo to give 3-isothio-
cyanatotricyclo[2,2,1,02'6]heptane, b.p. 70-76 at 0.4 mm. Hg.
pressure.
This isothiocyanate (1.2 g.) was dissolved in chloro-
form (30 ml.) and to it was added p-chloroaniline (2.1 g.).
The latter rapidly dissolved and the mixture was refluxed for
3 hours. The cooled solution was extracted with aqueous 2N HCl
(10 ml.), washed with water (10 ml.) and dried over anhydrous
MgSo4. After filtration, the solvent was èvaporated in vacuo
and the solid residue recrystallised from toluene to give 3-[3-(_-
chloropheny~thioureido]tricyclo[2,2,1,02'6]heptane, m.p. 164-166.
Example 12
8-[3-(~-Chlorophenyl)thioureido]tetracyclo[4,3,0,0 '4,
03'7]nonane (0.30 g.) was dissolved in ethanol saturated with
ammonia (100 ml.) at room temperature and stirred with yellow
mercuric oxide (0.43 g.) for 6 hours. The mixture was then
boiled for 15 minutes to remove excess ammonia, filtered and
the filtrate evaporated to dryness. The solid residue was
recrystallised from toluene/cyclohexane (1:2 v/v) to give 8-[3-
(~-chlorophenyl)guanidino]tetracyclo[4,3,0,02'4,03'7]nonane,
m.p. 170-171.
The thiourea used as starting material may be prepared
- 23 -
t
- . , ... -
:. .,; , '- ~ ' :
.
1087180
as follows:-
8-Aminotetracyclo[4,4,0,02'4,03'7]nonane hydro-
chloride (0.5 g.) (prepared as described in U.K. Patent
Specification 1,180,749) was dissolved in a mixture of chloro-
form (25 ml.) and triethylamine (0.33 g.). To this solutionwas added p-chlorophenylisothiocyanate (0.5 g.) and the mixture
refluxed for 16 hours. The chloroform solution, after cooling,
was washed successively with 10 ml. portions of 2N HCl, water
and saturated brine, and then dried over anhydrous MgS04.
After filtration, the solvent was evaporated in vacuo and the
residue crystallised from toluene/cyclohexane (1:2 v/v) to give
8-[3-(~2,-chlorophenyl)thioureido]tetracyclo[4,3,0,02'4,03'7]-
nonane, m.p. 168-170.
Example 13
2-Endo-aminobicyclo[2,2,1]heptane hydrobromide
(0.96 g.) was intimately mixed with p-chlorophenylcyanamide
(0.76 g.) and heated at 200-220 for 15 minutes. The mixture
quickly liquefied and was stirred occasionally. It was
allowed to cool and then treated with ethyl acetate (10 ml.)
and water (5 ml.) which dissolved the residue. The organic
phase was extracted three times with 5 ml. amounts of water.
The aqueous phases were combined and basified with aqueous lON
NaOH. The precipitated solid was filtered off, washed with
water, dried and shown by t.l.c. to be pure guanidine. The
ethyl acetate layer was shown by t.l.c. still to contain the
required guanidine. It was therefore extracted with 2N NaOH
(3 x 5 ml.), dried over anhydrous X2C03, filtered and evaporated
- 24 -
:;:
.~
- . ~
,
'
~,~
7~80
and the residue recrystallised from toluene to give 2-endo-[3-
(p-chlorophenyl)guanidino]bicyclo[2,2,1]heptane, m.p. 179-181.
Example 14
~ -Chloroaniline hydrochloride (1.25 g.) was dissolved in
n-butanol (10 ml.) and heated to reflux. A cold solution of 2-exo-
cyanamidobicyclo[2,2,1]hept-5-ene (1.07 g.) in butanol (10 ml.)
was added slowly dropwise so that the mixture continued to reflux.
One hour after the addition was complete the mixture was cooled,
butanol evaporated off in vacuo and the residue dissolved in ethyl
acetate (10 ml.). The organic phase was extracted with water (4
x 5 ml.). The combined aqueous phases were brought to pH7 with
aqueous Na2CO3 solution and extracted with ether. This removed un-
reacted ~-chloroaniline. The residual aqueous phase was brought to
pH 12 with aqueous 10N NaOH which precipitated pure product. It
was filtered off, washed with water, dried and recrystallised from
ethyl acetate to give 2-exo-[3-(~-chlorophenyl)guanidino]bicyclo-
[2,2,1]hept-5-ene, m.p. 206-207.
The 2-exo-cyanamidobicyclo[2,2,1]hept-5-ene used as start-
ing material may be obtained as follows:
2-Exo-isothiocyanatobicyclo[2,2,1]hept-5-ene (50 g.) was
dissolved in ethanol (200 ml.) and concentrated aqueous ammonia
~S.G. 0.88, 10 ml.) added. This mixture was refluxed and a further
~50 ml.) of concentrated aqueous ammonia added dropwise over 30
minutes. After 3 hours total reflux, the solution was cooled and
the required product crystallised out, to give 2-exo-thioureidobi-
cyclo[2,2,1]hept-5-ene (50.35 g.), m.p. 158-159.5.
- 25 -
10~180
This thiourea (1.0 g.) was dissolved in absolute
ethanol (50 ml.) at room temperature and freshly prepared
yellow mercuric oxide tl.29 g.) added. The mixture was stirred
for 24 hours at room temperature and a further portion of HgO
5 (1.29 g.) added. After a further 48 hours stirring the solids
were filtered off and washed well with ethanol. The filtrate
was taken to dryness in a rotary evaporator keeping the
temperature as low as possible. The 2-exo-cyanamidobicyclo-
[2,2,1]hept-5-ene thus obtained as a very pale brown gum was
dissolved in cold n-butanol (10 ml.) and used immediately.
Example 15
2-Exo-[3-(p-chlorophenyl)thioureido]bicyclo[2,2,1]-
hept-5-ene (0.5 g.~ was dissolved in ethanol (10 ml.) and iodo-
methane (0.255 ~ ) added. The mixture was refluxed for 3 hours,
during which time the thiourea was converted completely to the
S-methylthiouronium iodide. The mixture was cooled and then
saturated with ammonia gas. The mixture was refluxed with a
constant stream of ammonia passing through for 10 hours, cooled
to room temperature~saturated again with ammonia and left to
stand for 3 days.
The solvent was evaporated off and the residue taken
up in ethyl acetate (10 ml.). An insoluble portion (ammonium
iodide) was filtered off and the organic phase extracted with
water (4 x 10 ml.). The combined aqueous extracts were basified
with lON NaOH and the precipitate filtered off, washed with
water and dried. After recrystallisation from ethyl acetate
there was obtained 2-exo-[3-(p-chlorophenyl)guanidino]bicyclo-
- 26 -
- - . : ,
., ~ - .
': , ' ' : , ..
10~7180
t2,2,1]hept-5-ene, m.p. 202-203.
Example 16
A solution of 2-exo-~3-(~-chlorophenyl)guanidino]-
bicyclo[2,2,1]hept-5-ene (6.1 g.) in hot ethanol (75 ml.) was
stirred while a solution of (+)- mandelic acid (3.54 g.) in
hot ethanol (25 ml.) was added dropwise. The mixture was
allowed to cool slowly over 16 hours when the precipitate was
filtered off, then stirred with a 10 ml. portion of ethanol and
refiltered. The two filtrates were combined and retained. The
901id filtered off was recrystallised 3 times from ethanol, and
then had m.p. 159-162. This solid was stirred with 2N NaOH
(20 ml.) for 15 minutes, giving the free base of the resolved
guanidine, which was filtered off, washed with water (10 ml.)
and dried. The solid was recrystallised from ethyl acetate
giving (+)-2-exo-[3-(~-chlorophenyl)guanidino]bicyclo[2,2,1]-
hept-5-ene, m.p. 205-207, [a]Dl= + 73 (c, 1.0 in methanol).
The retained filtrates from the (+)- mandelate salt
were evaporated to dryness in vacuo and the base liberated by
stirring with cold 2N NaOH (20 ml.). The base was filtered off,
washed with water and dried giving 3.0 g. of solid. This was
dissolved in hot ethanol (45 ml.) and a solution of (-)- mandelic
acid (1.75 g.) in hot ethanol (20 ml.) added. The mixed solutions
were allowed to cool slowly over 16 hours. The precipitate was
filtered off, washed with ethanol (10 ml.) and then recrystallised
twice from ethanol, giving a salt with m.p. 159.5-162.
The free base was liberated as above, and after one
crystallisation from ethyl acetate gave (-)-2-exo-[3-(~-chloro-
- 27 -
1087180
phenyl?guanidino]bicyclo~2,2,1]hept-5-ene, m.p. 205-207,
~a]Dl= -73 (c, 1.0 in methanol).
-- 28 --
. . . - - .
.
. - : ~ :
