Method of preparing isomers of bis isoquinolinium compounds

This invention provides the neuromuscular blocking agents of formula (I): ##STR1## where B and C are each a group of formula (II) and are meta or para to one another: ##STR2## wherein D is CH.sub.2 CH.sub.2 or CH.dbd.CH (preferably trans); Y is alkyl of 1-4 carbon atoms (methyl, ethyl, propyl or butyl); E and F and H or OCH.sub.3 ; X.sup.- is an anion, preferably pharmaceutically acceptable; and the substituted benzyl and substituted propyl groups are in a trans relationship relative to each other in the nitrogen-containing ring. Methods for preparing the compounds, pharmaceutical formulations containing the compounds, and their use are also described.

BACKGROUND OF THE DISCLOSURE 
In anesthesia, neuromuscular blocking agents are used to provide skeletal 
muscular relaxation during surgery and during intubation of the trachea. 
In general there are two types of neuromuscular blocking agents in use, 
non-depolarizing and depolarizing. 
The non-depolarizing agents include d-tubocurarine, pancuronium, gallamine, 
diallyltoxiferine and toxiferine. 
The depolarizing agents include succinylcholine and decamethonium. All of 
the conventional non-depolarizing agents when used for producing skeletal 
muscle relaxation in surgery have a long duration of action, e.g. 60 to 
180 minutes in man. The depolarizing agents, on the other hand, provide 
muscle relaxation with duration of action shorter than that of the 
non-depolarizing agents. 
For example, succinylcholine provides a short duration of action of about 5 
to 15 minutes whereas decamethonium provides about 20 to 40 minutes 
duration of muscle relaxation in man. 
The long duration of action of non-depolarizing agents is unacceptable in 
many surgical procedures which take less than one hour because the patient 
is not generally fully recovered from their effects e.g., the patient may 
be unable to breathe adequately on his or her own. 
Each non-depolarizing agent has inherent side effects. For example, 
gallamine and pancuronium may cause tachycardia, and d-tubocurarine and 
diallyltoxiferine may cause hypotension. 
While these drugs can be pharmacologically antagonized with 
anticholinesterase agents, this obviously necesssitates the administration 
of a second drug which itself may have its own side effects, e.g., 
bradycardia, gut spasm and bronchorrhea. Thus, to overcome the 
aforementioned side effects of the anticholinesterase agents, a third 
drug, an anticholinergic drug, e.g. atropine must also be given. 
The depolarizing agents to the best of applicants' knowledge have no 
pharmacologic antagonists. While in most cases there is no need to reverse 
the effects of the depolarizing agents, in certain patients the effects of 
succinylcholine are much prolonged because of abnormal metabolism of the 
agent by the patient. 
The depolarizing agents due to that mode of action which initially causes 
skeletal muscle contraction and stimulation of smooth muscles are also 
known to cause the following side effects in certain instances: increased 
intraocular, and intragastric tension, cardiac arrhythmias, potassium 
release, and muscle pain. 
These side effects caused by the depolarizing agents are not caused by the 
non-depolarizing agents. It is, therefore, clearly evident that a new 
neuromuscular blocking agent is needed which would combine the short 
duration of action of the depolarizing agents with the relatively few side 
effects and the reversibility of the non-depolarizing agents. 
It should be understood that while non-depolarizing agents generally have 
few side effects, gallamine and pancuronium may cause tachycardia and 
d-tubocurarine and diallyltoxiferine may cause hypotension. 
Surprisingly, the compounds of the present invention appear to be free of 
these side effects at the dosages anticipated being used clinically in 
tests made to date. Reference may be made to the text: 
The Pharmacological Basis of Therapeutics-Fifth Edition, edited by Louis S. 
Goodman and Alfred Gilman published by The McMillian Co., copyright 1975, 
Chapter 28, author George B. Koelle, for further description of 
neuromuscular blocking agents. 
Reference should also be made to the following articles: 
Neuromuscular Blocking Activity of a New Series of Quaternary N-Substituted 
Choline Esters--British Journal of Pharmacology, September, 1971, vol, 43, 
No. 1, p. 107. 
The Pharmacology of New Short Acting Non-depolarizing Ester Neuromuscular 
Blocking Agents: Clinical Implications--published in Anaesthesia and 
Analgesia . . . Current Researches, Vol. 52, No. 6, p. 982, 
November-December, 1973. 
Potential Clinical Uses of Short-Acting Non-depolarizing 
Neuromuscular-Blocking Agents as Predicted from Animal 
Experiments--published in Anaesthesia and Analgesia . . . Current 
Researches, Vol. 54, No. 5, p. 669, September-October, 1974; and 
U.S. Pat. No. 3,491,099, for a further description of neuromuscular 
blocking agents. 
British Pat. No. 3004031 granted Oct. 10, 1961 discloses a group of 
substituted laudanosinium salts having neuromuscular blocking activity 
with non-depolarizing properties. 
Belgium Pat. No. 869,415 granted Jan. 31, 1979 discloses a group of 
substituted tetrahydroisoquinolinium salts having neuromuscular blocking 
activity, with non-depolarizing properties and a short duration of action. 
Spanish Patent of Invention No. 477.257 granted Apr. 25, 1979 [notice 
published in Spanish Official Gazette of Aug. 1, 1979] discloses a second 
group of substituted tetrahydroisoquinolinium salts having neuromuscular 
blocking activity, with non-depolarizing properties and an intermediate 
duration of action. The compounds disclosed in the above-mentioned patents 
comprise various mixtures of cis and trans isomers of undefined 
compositions. 
The four asymmetric centers present in each compound in all the above 
mentioned patents allow for sixteen possible stereoisomers. However, only 
ten stereoisomers can exist due to the symmetry of the molecular 
structure; for dl pairs (one all trans, one all cis, two cis, trans) and 
two meso forms (one all cis, one all trans). It is now recognized that the 
route of synthesis as well as the actual experimental conditions 
determines the cis/trans ratio and the stereoisomeric ratio. None of the 
issued patents addresses the question of the stereoisomers, hence they do 
not teach or even suggest ways for separating the different isomers. 
Moreover, the above mentioned patents do not teach or suggest that 
different potencies, durations of action or side effects would exist for 
the different isomers in the mixtures. 
We have discovered a way of providing the all trans (one dl pair, one meso 
form) and the all cis (one dl pair, one meso form) compounds. These 
diastereomers exhibit different neuromuscular blocking activities in their 
potencies and/or durations of action. In the cat, the all trans compounds 
showed superior potencies, three to six times that of the corresponding 
all cis compound and a shorter duration of action. In the monkey, the 
difference in potencies was not as evident, but the durations of action of 
the all trans compounds were markedly shorter (2-3 times) of those of the 
all cis compounds. The unexpected differences in duration were explained 
by measuring the hydrolysis rates by acetylcholinesterase in vitro. The 
rates of hydrolysis of the cis compounds were very slow compared to that 
of the corresponding trans form. 
Accordingly, this invention provides new neuromuscular blocking agents 
(sometimes called muscle relaxants) of the formula (I): 
##STR3## 
where B and C are each a group of formula (II) and are meta or para to one 
another: 
##STR4## 
wherein D is CH.sub.2 CH.sub.2 or CH.dbd.CH (preferably trans); Y is alkyl 
of 1-4 carbon atoms (methyl, ethyl, propyl or butyl); E and F are H or 
OCH.sub.3 ; X.sup.- is an anion, preferably pharmaceutically acceptable; 
and the substituted benzyl and substituted propyl groups are in a trans 
relationship relative to each other in the nitrogen-containing ring. 
Preferred compounds are those wherein Y is methyl. 
Compounds having particularly good potency combined with a short duration 
of action are 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl}1,3-phenylenedipropionate salts, particularly 
as the dichloride, diiodide or ditosylate salts. 
Compounds having particularly good potency combined with an intermediate 
duration of action are 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl}1,4-phenylene-(E,E)-diacrylate and 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl}1,3-phenylene-(E,E)-diacrylate salts, 
particularly as the dichloride, diiodide or dimesylate salts. 
Since the activity of the compounds of the invention resides in the 
dication, the nature of the anion X.sup.- is relatively unimportant. 
Suitable pharmaceutically acceptable anions include iodide, mesylate, 
tosylate, bromide, chloride, sulphate, phosphate, hydrogen phosphate, 
acetate, benzenesulphonate, succinate, maleate, naphthalenesulphonate and 
propionate. 
It will be appreciated that the compounds of the invention exist as an 
approximately 1:1 mixture of the racemic (dl) pair and the meso-isomer. 
This invention further provides means for obtaining the compounds of 
formula (I) when in the form of one of the aforesaid isomers substantially 
free of the other isomers, and mixtures of one of the isomers with one or 
both of the other isomers. 
It is preferred that the compounds of the invention be provided in a form 
where the ratio of the trans, trans compound of the invention to the total 
of any corresponding cis, cis and cis, trans compounds present as 
impurities is at least 96:4. 
The compounds of formula (I) are used as neuromuscular blocking agents in 
conjunction with surgery or for intubation of the trachea by conventional 
parenteral administration, e.g. intramuscular or intravenous 
administration in solution. The compounds of the present invention shown 
in formula (I) are administered to patients such as monkeys and man 
(humans) and other mammals to achieve a neuromuscular block. The dosage 
for each type of patient will vary because of the peculiarities of the 
species. However, a suitable intravenous amount or dosage of the compounds 
of formula (I) to obtain paralyses for monkeys and humans suitable for 
surgery would be 0.05 to 1.5 mg/kg of body weight, and most preferably 0.1 
to 1.0 mg/kg of body weight, the above being based on the weight of the 
dication which is the active ingredient. 
The dosage for intramuscular administration is two to four times the 
intravenous dose. The compounds of this invention would normally be 
readministered about every 5 to 45 minutes, depending on whether the 
activity of the compound is of short or intermediate duration, preferably 
every 5 to 30 minutes, after initial administration or given as a 
continuous infusion depending upon the length of time a muscular block is 
desired, and as determined by the anaesthetists and surgeon in charge of 
the patient. The compounds of this invention are reversible using 
conventional anticholinesterase agents such as neostigmine and edrophonium 
and appear to avoid the side effects associated with the depolarizing 
agents. 
The compounds of formula (I) are therefore useful for producing a short or 
intermediate duration neuromuscular blockade, and the present invention 
provides a method of producing such blockade in mammals, e.g. man, or 
monkeys, by intravenously injecting a dose of 0.05 to 1.5 mg/kg to the 
mammal. 
The compounds may be presented in a pharmaceutical formulation for 
parenteral administration. The formulation may be an aqueous or 
non-aqueous solution or emulsion in a pharmaceutically acceptable liquid 
or mixture of liquids, which may contain bacteriostatic agents, 
antioxidants, buffers, thickening agents, suspending agents or other 
pharmaceutically acceptable additives. Such formulations are normally 
presented in unit dosage forms such as ampoules or disposable injection 
devices, or in multidose forms such as a bottle from which the appropriate 
dose may be withdrawn, all such formulations sterile. 
The compounds of this invention may be presented as a powder, e.g. as a 
unit dose in a sealed vial to which sterile water or other 
pharmaceutically acceptable sterile liquid vehicle may be added, 
preferably by aseptic techniques. 
A suitable unit dose to obtain a neuromuscular block for mammals, e.g. 
humans or monkeys is about 1.0 mg to 300 mg and most preferably 5.0 to 200 
mg. 
The compounds of this invention if desired may be administered in 
conjunction with other non-depolarizing agents such as listed above. 
Thus a suitable pharmaceutical parenteral preparation for administration to 
human will preferably contain 1.0 to 300 mg of the compounds of formula 
(I) of this invention in solution. 
A simple and preferred formulation is a solution of the compound of formula 
(I) in water which may be prepared by simply dissolving the compound into 
previously sterilized pure water, i.e. pyrogen free water under aseptic 
conditions and sterilizing the solution. 
The compound of formula (I) may also be administered as an infusion of a 
dextrose solution or a saline solution, e.g. Ringers' solution. 
The compounds may also be administered in other solvents such as alcohol, 
polyethylene glycol and dimethylsulphoxide. They may also be administered 
intramuscularly as a suspension. 
The compounds of this invention provide the same percentage neuromuscular 
block at unexpectedly lower doses than the previously described cis/trans 
mixtures. Consequently, the possibility of side effects such as abnormal 
lowering of blood pressure, histamine release, tachycardia, etc. is 
substantially reduced. Furthermore, our invention provides means to 
prepare mixtures of specified isomeric composition. 
The compounds of formula (I) may be prepared by the following methods, 
using a substituted tetrahydroisoquinolinium salt having the trans 
configuration as previously defined. 
Method 1 
Benzyltetrahydroisoquinolins are prepared in the customary fashion from 
homoveratrylamine or mescaline and homoveratric acid or 
3,4,5-trimethoxyphenylacetic acid via the Bischler-Napieralisky reaction 
and reduction/alkylation. 
The tertiary benzyltetrahydroisoquinoline is quaternized with an 
appropriate 1,3-dihalopropane, such as 1-bromo-3-chloropropane 
3-chloro-1-iodopropane or 3-bromo-1-iodopropane. From the resulting 
N-alkyl-N-3-halopropyl-1-benzyltetrahydroisoquinolinium halide the trans 
isomer is separated and is boiled in water with the silver salt of the 
appropriate dicarboxylic acid, yielding silver halide and the 
benzyltetrahydroisoquinolinium salt of the acid. This salt reacts to the 
corresponding ester on heating, preferably at 90.degree. to 140.degree. C. 
For example, the generalized reaction is illustrated as follows: 
##STR5## 
where D, Y, E and F are as defined above. The desired salts are then 
prepared by ion exchange using conventional methods such as metathesis 
with HX or a silver salt, an anion exchange resin, etc. 
Method 2 
The appropriate 1-benzyltetrahydroisoquinoline prepared as described in 
Method 1 is quaternized with a 3-halopropanol such as 3-iodo, 3-bromo, or 
3-chloropropanol. This is illustrated below where E, F, X and Y are as 
defined above. 
##STR6## 
This process may be carried out in a variety of solvents (e.g., 
acetonitrile, lower alcohols, DMF, water, aromatic hydrocarbons, etc) over 
temperatures ranging from ambient to reflux. The trans isomer is separated 
as described below. 
The bis acid chloride of an appropriate meta- or para-phenylene 
dicarboxylic acid is prepared in the usual fashion by treatment with a 
reagent such as thionyl chloride. 
The bis acid chloride is then esterified with, e.g., two moles of the 
appropriate quaternary salt containing a 3-hydroxypropyl chain. This is 
illustrated below where D, E, F, X and Y are as defined above. 
##STR7## 
To prepare the all trans bis quaternary salts, having enhanced potencies 
and greater freedom from side effects, requires the preparation of a 
trans-N-3-hydroxypropyl-N-alkyltetrahydroisoquinolinium salt with a total 
of 4-6 methoxy groups as described in formula (II) for coupling with the 
meta or para-phenylene dipropionic or diacrylic acids. Trans and 
cis-N-3-hydroxypropyl-5'-methoxylaudanosinium salts, for example, are 
diastereomers and theoretically separable by physical methods, e.g. 
crystallization. However, literature precedent suggests that this 
separation is difficult. For example Stenlake et al. [J. B. Stenlake, W. 
D. Williams, N. C. Dhar, and I. G. Marshall, Eur. J. Med. Chem.--Chimica 
Therapeutica, 9, 233 (1974)] reported the synthesis of mixtures of trans 
and cis N-ethyllaudanosinium iodides but were unable to separate them: 
"All attempts to separate the components of these mixtures by 
crystallization and chromatographic techniques were unsuccessful." We 
examined a variety of solvents for recrystallization of the trans/cis 
mixtures of N-3-hydroxypropyl-5'-methoxylaudanosinium iodide (trans/cis 
ratio about 2.5-2.7/1) afforded by quaternization of 5'-methoxylaudanosine 
with 3-hydroxypropyl iodide (See Table I). Most solvent categories were 
unsatisfactory. The mixture of trans/cis quaternary iodides was largely 
insoluble in ethers (tetrahydrofuran, 1,4-dioxane, 1,2-dimethoxyethane), 
esters (ethyl acetate, ethyl propionate), ketones (acetone, 2-butanone), 
and aromatic hydrocarbons (benzene, toluene, xylene). The insoluble 
residues showed little or no enrichment with trans isomer. Solvents useful 
for the separation included acetonitrile, some chlorinated hydrocarbons 
(e.g. dichloromethane, 1,2-dichloroethane), some alcohols (e.g. ethanol, 
2-propanol), and water. Water is the most preferred solvent. Once 
enrichment of the trans isomer has been accomplished (e.g. by water 
recrystallization) further recrystallization from a variety of solvents 
(e.g. acetonitrile, ethanol) or trituration with acetone suffices to raise 
the trans content to .about.98% or higher. 
TABLE I 
__________________________________________________________________________ 
Separation of Trans/Cis N--3-Hydroxypropyl-5'-methoxylaudanosinium 
Iodide 
A sample of trans/cis iodide (2.6/1 by HPLC) was heated in a solvent, 
filtered 
hot, cooled to 25.degree. and filtered again. 
Trans/Cis Ratio (Recovery) 
Insoluble 
Recrystallized 
Solvent Concentration (ml/g) 
Salts Salts 
__________________________________________________________________________ 
tetrahydrofuran 
10 2.7/1 (90%) 
NP 
1,4-dioxane 10 2.8/1 (71%) 
NP 
1,2-dimethoxyethane 
10 2.6/1 (83%) 
NP 
acetone 10 2.7/1 (81%) 
1.1/1 (1%) 
2-butanone 10 3.4/1 (82%) 
1/1.1 (8%) 
ethyl propionate 
10 2.7/1 (96%) 
NP 
ethyl acetate 
10 2.6/1 (88%) 
NP 
acetonitrile 10 CS 1/2.6 (28%) 
dichloromethane 
2 1/15.8 (21%) 
chloroform 2 CS 1/6.2 (2%) 
carbon tetrachloride 
10 2.6/1 (96%) 
NP 
1,2-dichloroethane 
5 1/1.2 (30%) 
4/1 (58%) 
nitromethane 2 CS 1/1 (30%) 
nitroethane 2 CS 2.3/1 (89%) 
benzene 10 2.7/1 (.about.100%) 
NP 
toluene 10 2.7/1 (.about.100%) 
NP 
xylene 10 2.5/1 (.about.100%) 
NP 
methanol 2 CS 6.8/1 (9%) 
ethanol 5 9.8/1 (27%) 
1.9/1 (58%) 
2-propanol 5 12.7/1 (38%) 
1.5/1 (25%) 
2-methoxyethanol 
2 CS 2.8/1 (31%) 
formamide 2 CS NP 
N,N--dimethylformamide 
2 CS NP 
N--ethylacetamide 
2 CS 2.6/1 (96%) 
Dimethyl sulfoxide 
2 CS NP 
Hexamethylphosphoramide 
2 CS NP 
Water 6.74 CS 1/5.17 (31%) 
__________________________________________________________________________ 
Abbreviations: NP = No Precipitate, NA = Not Assayed, CS = Complete 
Solution 
In another approach to the separation of trans/cis quaternary salt mixtures 
the iodide was first changed to a different anion. The mixture of iodides 
was converted to the corresponding chlorides by standard methods (anion 
exchange chromatography, metathesis with silver chloride, and metathesis 
with HCl gas) and a variety of solvents was examined, for separating the 
isomers (See Table II). Again, most solvents were unsatisfactory. Among 
ethers only 1,4-dioxane was selective. Ketones, esters, and aromatic 
hydrocarbons were ineffective. Nitroalkanes (nitromethane, nitroethane), 
acetonitrile, some alcohols (especially ethanol and 2-propanol), some 
chlorinated hydrocarbons (e.g. dichloromethane, 1,2-dichloroethane), 
dimethylsulfoxide, hexamethylphosphoramide, and N-substituted amides are 
useful solvents for obtaining the quaternary chloride enriched in the 
trans isomer. N-substituted amides (e.g. N,N-dimethylformamide, 
N,N-dimethylacetamide, N-formylpiperidine, N-formylmorpholine, 
N-methylformamide, N-methylacetamide, and N-ethylacetamide) are preferred 
solvents for the trans/cis separation. These amides may be used as 
recrystallization solvents or solvents for slurrying enriched trans 
mixtures to increase further the trans isomer content. 
TABLE II 
__________________________________________________________________________ 
Separation of Trans/Cis N--3-Hydroxypropyl-5'-methoxylaudanosinium 
Chloride 
A sample of trans/cis iodide (2.9/1 by HPLC) was heated in a solvent, 
filtered 
hot, cooled to 25.degree. and filtered again. 
Trans/Cis Ratio (Recovery) 
Insoluble 
Recrystallized 
Solvent Concentration (ml/g) 
Salts Salts 
__________________________________________________________________________ 
tetrahydrofuran 
10 2.6/1 (97%) 
NP 
1,4-dioxane 10 132/1 (67%) 
1/6 (24%) 
1,2-dimethoxyethane 
10 3.3/1 (96%) 
NP 
acetone 10 3/1 (95%) 
1/15 (2%) 
2-butanone 10 3.8/1 (97%) 
1/11 (3%) 
ethyl propionate 
10 3.4/1 (99%) 
NP 
ethyl acetate 
10 3.3/1 (95%) 
NP 
acetonitrile 10 100/1 (50%) 
8.6/1 (6%) 
dichloromethane 
10 101/1 (36%) 
NP 
chloroform 2 CS NP 
carbon tetrachloride 
10 2.4/1 (99%) 
NP 
1,2-dichloroethane 
10 6/1 (76%) 
1/2.9 (12%) 
nitromethane 5 CS 9.4/1 (56%) 
nitroethane 10 80/1 (42%) 
NP 
benzene 10 2.9/1 (99%) 
NP 
toluene 10 3.1/1 (97%) 
NP 
xylene 10 2.4/1 (96%) 
NP 
methanol 2 CS NP 
ethanol 5 CS 17/1 (32%) 
2-propanol 10 69/1 (30%) 
9.1/1 (18%) 
2-methoxyethanol 
formamide 2 CS NP 
N,N--dimethylformamide 
5 CS 6.7/1 (54%) 
N--ethylacetamide 
2 CS 8.8/1 (76%) 
Dimethyl sulfoxide 
2 CS 18/1 (34%) 
Hexamethylphosphoramide 
10 67/1 (40%) 
NP 
Water 2 CS NP 
__________________________________________________________________________ 
Abbreviations: NP = No Precipitate, NA = Not Assayed, CS = Complete 
Solution 
We have found that a particularly good separation of the trans isomer from 
the crude cis/trans mixture may be achieved by crystallization of the 
N-(3-hydroxypropyl)-N-methyl compound in the form of the iodide (cis/trans 
mixture) from water. The cis-isomer crystallizes preferentially. If 
required, the trans-enriched filtrate may then be converted to the 
chloride, for example, by conventional anion exchange chromatography (e.g. 
using Dowex 1-X8 chloride resin), and the solute recovered and slurried 
with dimethylformamide, when the cis-isomer preferentially dissolves, to 
leave a product containing only a trace of the cis-isomer. 
We have also separated the trans/cis mixture of 
N-3-hydroxypropyllaudanosinium iodide; 
N-3-hydroxypropyl-8-methoxylandanosinium iodide; and 
N-3-hydroxypropyl-5'-8-dimethoxylaudanosinium iodide by fractional 
crystallization. 
It is desirable to use an intermediate having less than about 2% of the 
corresponding cis-isomer, in order to obtain a compound of formula (I) 
containing less than 4% of the cis, cis and cis, trans isomers. This 
degree of separation may be readily achieved using the processes outlined 
above. 
Method 3 
The appropriate 1-benzyltetrahydroisoquinoline prepared as described in 
Method 1 is quaternized with a 3-halopropanol such as 3-iodo, 3-chloro or 
3-bromopropanol, and the 
trans-N-3-hydroxypropyl-1-benzyltetrahydroisoquinolinium salt is separated 
from the cis isomer as in Method 2. 
The trans quaternary salt is coupled with the appropriate meta- or 
para-phenylenedipropionic acid by direct esterification. This method may 
also be used to couple the trans-quaternary salt with meta or 
para-phenylenediacrylic acid, but this reaction is slower. This operation 
is carried out in a suitable solvent (e.g. 1,2-dichloroethane) using an 
acid catalyst (e.g. p-toluenesulfonic acid). The reaction is driven toward 
comopletion by removal of water by use of drying agents (e.g. molecular 
sieves) or by azeotropic distillation. Temperatures ranging from ambient 
to reflux may be employed. The final salt may be changed if desired by 
conventional anion exchange methods. 
As previously stated, the compounds of formula (I) exist in three 
stereoisomeric forms, which may be separated from each other, if desired, 
by conventional methods. For example, the meso-isomer may be separated 
from the (dl)-pair by fractional crystallization, or by preparative HPLC, 
and the d- and l-isomers may be separated from each other by conversion to 
a salt of a single isomer of an optically active acid, followed by 
fractional crystallization. The product may then, if desired, be converted 
to an alternative salt by conventional anion exchange methods. 
m- and p-phenylene diacrylic acids were prepared through 
Knoevenagel-Doebner condensation of isophthalic and terephthalic aldehydes 
with malonic acid. Terephthalic aldehyde (150 mM) and malonic acid (180 
mM) were mixed with pyridine (45 ml) and piperidine (1.5 ml). The mixture 
was heated on a steam bath (85.degree.-95.degree.) for 3 hours. The 
solution was then cooled at room temperature and distilled in vacuum to 
remove pyridine. The solid residue was washed in hot 2-propanol 
(70.degree.) to remove residual pyridine. The product, p-phenylene 
diacrylic acid, was filtered and dried (mp&gt;275.degree.). 
m-Phenylene diacrylic acid was prepared from isophthalaldehyde in exactly 
the same way. (mp&gt;275.degree.). 
m- and p-phenylene dipropionic acids may be prepared using conventional 
processes by catalytic reduction, e.g. by reacting the corresponding 
phenylene diacrylic salt with hydrogen at 40 to 45 psi gauge pressure in 
the presence of 5% palladium on charcoal in water or dimethylformamide at 
room temperature to 55.degree. C. For another method, see also Wagner & 
Zook, Synthetic Organic Chemistry.COPYRGT. 1973, page 431, method 26. 
The compounds of this invention may sometimes include water of hydration in 
various amounts and it is intended that this invention include such 
compounds containing water of hydration.

The following examples illustrate the invention but are not intended to be 
limiting. Temperatures are in degrees centigrade (uncorrected). 
Primary analysis of the quaternary salt intermediates and the di-quaternary 
salt final products was accomplished by high performance liquid 
chromatography (HPLC). Samples dissolved in methanol were injected onto a 
25 cm.times.4 mm silica gel column and eluted with an acidic methanol. 
Detection was based on absorbance at 280 nm; percentages were derived by 
integration of the areas under the curves. Nuclear magnetic resonance 
(NMR) spectra, combustion analyses, and Karl Fischer water analyses were 
obtained as needed to support structures. The stereochemistry of the cis 
and trans quaternary salts was confirmed by x-ray crystallography of the 
cis iodide and the trans perchlorate of 
N-3-hydroxypropyl-5'-methoxylaudanosinium salts. 
EXAMPLE 1 
N-3-hydroxypropyl-5'-methoxylaudanosinium iodide (Belgian patent No. 
869,415 and West German Offenlegungsschrift No. 2833505) (50 g, 73% trans) 
was dissolved in 337 mL of hot water. The mixture was cooled to 30.degree. 
and then stirred at room temperature for 3 hours. The solids were 
collected by filtration and dried in a vacuum oven (60.degree./3 hr) to 
yield 15.5 g of solids analyzed by HPLC as 84% cis. The trans rich 
filtrate was applied to a 5.times.60 cm column packed with 110 g of Dowex 
1-X8 chloride in water and eluted with 100 mL of water. The eluate was 
concentrated in vacuo to dryness. The residue was triturated with 40 mL of 
acetone; the mixture was cooled to 5.degree. and filtered. The solid was 
vacuum dried (60.degree./3 hr) to yield 28 g of crude trans chloride. The 
crude product was slurried in dry DMF (70 mL) at 70.degree.-75.degree. 
for 15 minutes. The mixture was cooled to 5.degree. and filtered. The 
solids were washed with cold DMF (15 mL) and refluxed in acetone (100 mL) 
for 15 minutes. The suspension was cooled to 5.degree. and filtered; the 
solids were washed with cold acetone and dried in a vacuum oven to yield 
24.7 g (80.5%) of trans-N-3-hydroxypropyl-5'-methoxylaudanosinium 
chloride, mp 209.degree.-211.degree.. HPLC analysis showed this material 
to be 99.3% trans. 
EXAMPLE 2 
Crude N-3-hydroxypropyl-5'-methoxylaudanosinium iodide (95.1% pure, 71.9% 
trans by HPLC, 412 g) was recrystallized from 1348 mL of water. The trans 
rich mother liquor was chromatographed on 1.00 kg of Dowex 1-X8 chloride. 
The eluate and washings were combined and concentrated in vacuo to a 
viscous oil. The residue was triturated with 3000 mL of refluxing acetone. 
Approximately 2000 mL of acetone were removed by atmospheric distillation. 
The residual slurry was chilled and filtered to yield 225 g of crude trans 
chloride (97.7% trans). The crude product was slurried in 2 parts of DMF 
(w/v) for 30 minutes at 75.degree.. The mixture was cooled to 0.degree. 
and filtered. The cake was washed with the DMF liquors and then with 
acetone. Finally the damp product was slurried in 800 mL of refluxing 
acetone for 15 minutes and then the mixture was cooled, filtered, and 
dried to yield 206 g (87.0%) of 
trans-N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (99.9% trans by 
HPLC). 
EXAMPLE 3 
N-3-hydroxypropyl-5'-methoxylaudanosinium iodide (50 g, 72.5% trans, 26.7% 
cis) was dissolved in 337 mL of hot water. The solution was cooled to 
25.degree. for 3 hours. The mixture was filtered to yield 15.5 g of cis 
iodide (83.8% cis--purified (&gt;99% cis) by recrystallization from 
methanol). The filtrate was concentrated to dryness in vacuo to yield the 
trans iodide (95.6% trans by HPLC). The crude trans iodide was purified by 
recrystallization from dry acetonitrile (2.5 mL CH.sub.3 CN/g) to yield 
99.6% trans iodide (71% recovery). In similar experiments 94.5% trans 
iodide gave 99.3% pure trans (67% recovery) and 97% trans gave 99.6% trans 
(86% recovery). Trans iodide was also purified by trituration with acetone 
(3 mL/g): 92.7% trans gave 97.7% trans (95% recovery). Ethanol (95%, 4 
mL/g) could also be used as a recrystallization solvent: 97.7% trans gave 
99.6% trans (61% recovery). 
EXAMPLE 4 
Trans-N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (&gt;99% trans by 
HPLC, 25.7 g) was suspended in 375 mL of 1,2-dichloroethane and 50-75 mL 
of solvent was distilled off to remove any water present. The mixture was 
cooled to .about.70.degree. and 1,3-phenylenedipropionyl chloride (6 g, 
prepared by treatment of the corresponding acid with thionyl chloride) was 
added as a solution in dry 1,2-dichloroethane. The mixture was heated at 
reflux for 25 minutes; HPLC analysis indicated .about.93% of product. The 
reaction mixture was cooled, stirred over potassium carbonate for 2.5 
hours, filtered, and concentrated in vacuo to dryness. The crude product 
was dissolved in 300 mL of chloroform, and the solution was washed twice 
with 5% sodium chloride, twice with water, dried over anhydrous sodium 
sulphate, and concentrated in vacuo to give 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl} 1,3-phenylenedipropionate dichloride as a 
white amorphous solid, 24 g (87.4% based on a dihydrate). 
EXAMPLE 5 
Trans-N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (&gt;99% trans by 
HPLC, 124.6 g) was suspended in 1720 mL of dry 1,2-dichloroethane. The 
mixture was heated to reflux and 500 mL of solvent was removed by 
distillation. The mixture was cooled to 50.degree. and a solution of 
1,3-phenylenedipropionyl chloride, 32.7 g, in 100 mL of 
1,2-dichloroethane was added. The mixture was stirred at reflux for 45 
minutes and cooled to 8.degree.. Triethylamine, 22.9 g, was added giving 
an exotherm to 15.degree.. The mixture was cooled to 10.degree., stirred 
for 15 minutes, and concentrated in vacuo. The residue was stored at 
5.degree. overnight and then dissolved in 1800 mL of chloroform. The 
chloroform solution was washed with 5% sodium chloride (2.times.450 mL), 
water (2.times.450 mL), dried over magnesium sulphate, clarified by 
treatment with charcoal, and concentrated in vacuo until foaming began. 
The residue was triturated with hexane and the mixture concentrated in 
vacuo again until foaming began. This process was repeated three times 
until a solid product was obtained. The slightly oily product was 
transferred to a mortar and triturated again with hexane to give a 
granular solid which was collected by filtration and dried (48 hours at 
40.degree.) in a vacuum oven to yield 127.5 g (85.3%) of bis{3-[trans- 
1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxybenzyl)isoqui 
nolinium]propyl} 1,3-phenylenedipropionate dichloride. 
EXAMPLE 6 
Trans-N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (&gt;99% trans by 
HPLC), 5.06 g, was coupled with E,E-1,4-phenylenediacryloyl chloride, 1.27 
g, by the procedure of Example 4 to yield 3.0 g (50.7% as a dihydrate) of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl} 1,4-phenylene-(E,E)-diacrylate dichloride. 
EXAMPLE 7 
1,3-Phenylenedipropionic acid (0.58 g), 
trans-N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (3.2 g), 
p-toluenesulphonic acid monohydrate (1.75 g), and dichloroethane (60 mL) 
were combined in a 100 mL flask equipped with a sintered glass Soxhlet 
containing molecular sieve #4. The mixture was heated at reflux and was 
monitored by HPLC. After 35 hours the reaction mixture was cooled and 
washed with water (2.times.50 mL). The dichloroethane layer was stirred 
overnight with charcoal and magnesium sulphate (anhydrous). The mixture 
was filtered and evaporated to dryness to give 3.11 g (84%) of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl} 1,3-phenylenedipropionate ditosylate. 
EXAMPLE 8 
Trans-N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (5.00 g), 
1,3-phenylenediacrylic acid (1.08 g), and p-toluenesulfonic acid 
monohydrate were combined in 1,2-dichloroethane and reacted by the 
procedure of Example 7. After 99 hours at reflux HPLC analysis showed 
46.7% of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl} 1,3-phenylene-(E,E)-diacrylate ditosylate. 
EXAMPLE 9 
Trans-N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (&gt;99% by HPLC), 
5.07 g, was coupled with 1,4-phenylenedipropionyl chloride, 1.29 g, to 
yield 4.7 g (79.6% as dihydrate) of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)-isoquinolinium]propyl} 1,4-phenylenedipropionate dichloride. 
EXAMPLE 10 
To a solution of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]-propyl} 1,3-phenylenedipropionate diiodide 
tetrahydrate (0.65 g (prepared according to Example 4 using the pure trans 
iodide of Example 3) in acetonitrile (10 mL) was added to a solution of 
silver methanesulphonate (0.22 g) in acetonitrile (10 mL). The mixture was 
stirred for 15 minutes and filtered to remove the precipitate of silver 
iodide. The filtrate was concentrated in vacuo to a brown oil which was 
taken up in denatured ethanol (SD3A) and filtered to remove excess silver 
methanesulphonate. The alcohol was evaporated in vacuo, and the residue 
was dissolved in acetonitrile and filtered. The acetonitrile was 
evaporated in vacuo and the residue was dissolved in acetone. The acetone 
solution was filtered through Celite.RTM. (filter aid) and evaporated to 
dryness to yield 0.40 g (65%) of fluffy yellow crystals of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl} 1,3-phenylenedipropionate 
dimethanesulphonate. Calcd. for C.sub.62 H.sub.82 N.sub.2 O.sub.14 
.2CH.sub.3 O.sub.3 S.4H.sub.2 O: C, 57.29; H, 7.21; N, 2.08; S, 4.79 
Found: C, 57.37; H, 7.10; N, 2.09; S, 4.79. 
EXAMPLE 11 
N-3-Hydroxypropyl-5'-methoxylaudanosinium iodide (10 g, 71% trans) was 
dissolved in methanol (100 mL). The solution was heated to reflux and 
hydrogen chloride gas bubbled through for 5 hours. The mixture was 
evaporated in vacuo, and the residue was stored overnight in a dessicator 
containing sodium hydroxide pellets. Acetone was added and evaporated in 
vacuo. Denatured alcohol (SD3A) was added and evaporated in vacuo and the 
process repeated a second time. Upon the addition of acetone and seed 
crystals there was obtained 4 g of 
N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (87% trans by HPLC). 
Slurrying in DMF gave the trans quaternary chloride (&gt;98% trans by HPLC). 
EXAMPLE 12 
Trans-N-3-hydroxypropyl-5'-methoxylaudanosinium chloride (&gt;99% trans by 
HPLC), 5.06 g, was coupled with, E,E-1,3-phenylenediacryloyl chloride, 
1.27 g, by the procedure of Example 4 to yield 6.0 g (100% as trihydrate) 
of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxy 
benzyl)isoquinolinium]propyl} 1,3-phenylene-(E,E)-diacrylate dichloride. 
EXAMPLE 13 
5',8-Dimethoxylaudanosine (27.2 g) and 3-iodopropanol (27.2 g) were 
refluxed in dry acetone (150 mL) for 21 hr. High pressure liquid 
chromatography (HPLC) showed a cis/trans mixture of 1:4.3. The mixture was 
stripped to a gum and the excess iodopropanol was extracted with ether. 
The ether was decanted and the residual gum was dissolved in SD3A (300 mL) 
with slight warming. Cooling the alcoholic solution at 5.degree. overnight 
gave a white crystalline solid which was filtered and dried. The yield was 
29.2 g (73%) which was assayed as 89.9% of 
trans-N-3-hydroxypropyl-5',8-dimethoxylaudanosinium iodide and 10.1% of 
cis-N-3-hydroxypropyl-5',8-dimethoxylaudanosinium iodide. The mixture was 
recrystallized twice from SD3A (3.4 mL/g) to give 24.4 g (84% recovery) of 
a mixture assayed by HPLC as 97.8% trans and 2.2% cis iodides, mp 
160.degree.-163.degree. C. The mixture was dissolved in aqueous methanol 
(300 mL) and the solution was passed through a column packed with Dowex 
1-X8 ion exchange resin (75 g, Cl.sup.- form). The column was rinsed with 
methanol (150 mL) and the eluate and washings were combined, stripped to a 
white solid, triturated with acetone, filtered and dried. The yield was 
18.1 g (87%) which was assayed by HPLC as 100% trans. 
Calc. for C.sub.26 H.sub.38 NO.sub.7 Cl.2H.sub.2 O: C, 56.98; H, 7.72; N, 
2.56; Cl, 6.47; Found: C, 56.97; H, 7.74; N, 2.52; Cl, 6.47. 
EXAMPLE 14 
Trans-N-3-hydroxypropyl-5',8-dimethoxylaudanosinium chloride (2.0 g) was 
coupled with 1,4-phenylenedipropionyl chloride (0.48 g) by the procedure 
of Example 4 to yield 700 mg (31% as a tetrahydrate) of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7,8-trimethoxy-N-methyl-1-(3,4,5-trimeth 
oxybenzyl)isoquinolinium]propyl} 1,4-phenylenedipropionate dichloride. 
EXAMPLE 15 
According to the procedure of Example 13, laudanosine (34 g) was 
quaternized with 3-iodopropanol (26 g) to give a 3:1 ratio of trans/cis 
N-3-hydroxypropyllaudanosinium iodides. Crystallization of the crude 
mixture gave the pure trans iodide which was converted to the 
corresponding pure trans chloride (&gt;99% by HPLC). The yield for the 
quaternization was 87% and for the anion exchange was 82%. 
EXAMPLE 16 
Trans-N-3-hydroxypropyllaudanosinium chloride (3.6 g) was coupled with 
1,4-phenylenedipropionyl chloride (0.96 g) by the procedure of Example 4 
to yield 2.8 g (69% as a tetrahydrate) of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4-dimethoxyben 
zyl)isoquinolinium]propyl} 1,4-phenylenedipropionate dichloride. 
EXAMPLE 17 
Trans-N-3-hydroxypropyllaudanosinium chloride (5.0 g) was coupled with 
E,E-1,4-phenylenediacryloyl chloride (1.35 g) by the procedure of Example 
4 to yield 2.3 g (40% as a tetrahydrate) of 
bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4-dimethoxyben 
zyl)isoquinolinium]propyl} 1,4-phenylene-(E,E)-diacrylate dichloride. 
EXAMPLE 18 
Trans-N-[3-hydroxypropyl]-5',8-dimethoxylaudanosinium chloride (2.0 g), 
1,3-phenylenedipropionic acid (0.34) and p-toluenesulfonic acid 
monohydrate (0.94) were refluxed in 150 mL dichloroethane in a 500 mL one 
neck round bottom flask fitted with magnetic spin bar, Soxhlet extractor 
containing 4A.degree. molecular sieves, reflux condenser and drying tube. 
After 50 hrs, solvent was stripped at reduced pressure leaving 3.3 g of a 
gummy residue. The gum was dissolved in 50 mL warm isopropanol. After 
cooling at 0.degree. C., isopropanol was decanted from an oil which had 
settled. The oil was dissolved in 100 mL CHCl.sub.3 and washed with 100 mL 
H.sub.2 O. CHCl.sub.3 was stripped and the residue was dissolved in 50 mL 
warm methyl ethyl ketone. The solution was cooled and solvent was decanted 
from an oil. The material was lyophilized from CH.sub.3 OH to give 
trans,trans-2,2'-(1,3-phenylenebis(ethylenecarbonyloxytrimethylene))-bis(1 
,2,3,4-tetrahydro-6,7,8-trimethoxy-2-methyl-1-(3,4,5-trimethoxybenzyl)isoqu 
inolinium) ditosylate (also known as 
bis{3-[trans-1,2,3,4-tetrahydro-6,7,8-trimethoxy-N-methyl-1-(3,4,5-trimeth 
oxybenzyl)isoquinolinium]propyl} 1,3-phenylenedipropionate ditosylate), 
0.54 g (24%), 90.6% diester and 9.4% halfester by HPLC. Elemental analysis 
supports the ditosylate with 3.5 H.sub.2 O. 
Calc. for 0.96(C.sub.64 H.sub.86 N.sub.2 O.sub.16 2C.sub.7 H.sub.7 O.sub.3 
S)+0.094(C.sub.37 H.sub.50 NO.sub.10 C.sub.7 H.sub.7 O.sub.3 S)3.5 H.sub.2 
O: C, 60.52; H, 6.99; N, 1.80; S, 4.12; Cl, 0.0; Found: C 60.50; H, 6.81; 
N, 1.88; S, 3.50; Cl, 0.0. 
EXAMPLE 19 
The optically active enantiomers 
2,2'-(1,3-phenylenebis(ethylenecarbonyloxytrimethylene))bis((1R,2S)-1,2,3, 
4-tetrahydro-6,7,8-trimethoxy-2-methyl-1-(3,4,5-trimethoxybenzyl)isoquinoli 
nium) ditosylate and 
2,2'-(1,3-phenylenebis(ethylenecarbonyloxytrimethylene))bis((1S,2R-1,2,3,4 
-tetrahydro-6,7,8-trimethoxy-2-methyl-1-(3,4,5-trimethoxybenzyl)isoquinolin 
ium) ditosylate are synthesized by first resolution at the 1-position of 
the 5',8-dimethoxylaudanosine base to its R and S enantiomers. 
Quaternization of the R base followed by separation of the cis isomer 
(1R,2R) leads to the pure trans quaternary salt (1R,2S). The optically 
active trans quaternary salt (1R,2S) is then converted to the optically 
active diester. By utilizing the S base and proceeding through the same 
sequence the other enantiomer of the diester is obtained. 
Alternatively the trans N-(3-hydroxypropyl)-5',8-dimethoxylaudanosinium 
salt is resolved using a resolving agent to its enantiomers (1R,2S) and 
(1S,2R) which are then used to obtain the two enantiomers of the diester. 
As used herein R and S denote chirality according to the Cahn-Ingold-Prelog 
system [Angew. Chem. Int. Ed. Engl., 5, 385 (1966) and Pure Appl. Chem., 
45, 13 (1976)]. 
The RS, RS and SR, SR compounds are important because of their short-acting 
properties. 
Short acting as used herein is defined as having a duration of action of 
about 20 minutes or less. 
Pharmacological Activity 
Cynomolgus monkeys were anaesthetized with thiopental (35-40 mg/kg) and 
diazepam (2--3 mg/kg) given intramuscularly. Anaesthesia was maintained 
with a mixture of halothane (0.25-0.75%), nitrous oxide (60%) and oxygen 
(40%). 
Bis{3-[trans-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxyb 
enzyl)isoquinolinium]propyl} 1,3-phenylenedipropionate dichloride (compound 
A), 
bis{3-[1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxybenzyl 
)isoquinolinium]propyl} 1,3-phenylenedipropionate diiodide (mixture of cis 
and trans isomers, Compound B) or 
bis{3-[cis-1,2,3,4-tetrahydro-6,7-dimethoxy-N-methyl-1-(3,4,5-trimethoxybe 
nzyl)isoquinolinium]propyl} 1,3-phenylenedipropionate diiodide (Compound C) 
was administered intravenously. The common peroneal nerve was stimulated 
supramaximally with square wave pulses of 0.2 m sec duration at a rate of 
0.15 Hz. Twitch contractions were recorded via the tendon of the tibialis 
anterior muscle. 
The ED.sub.95, i.e. the dose required to produce 95% block of the twitch 
response, of compound A was 0.4-0.6 mg/kg and that of compound B was 
0.5-1.0 mg/kg and that of compound C was 0.8-1.1 mg/kg (expressed as mg/kg 
cation).