CA1229304A - Tricyclic compounds and their use - Google Patents

Abstract

ABSTRACT

Tricyclic compounds of formula (I)

Description

This invention relates to tricyclic compounds useful in medicine, to the preparation of such compounds, to forum-ceutical formulations and other presentation forms containing such compounds and the preparation thereof, to the use of the compounds in medicine, and to novel intermediates for the said compounds and the preparation thereof.
This Application is a divisional of Canadian Patent Application, Serial No. 426,692j filed on April 26, 1983.
The present invention more particularly relates to the novel tricyclic compounds of formula (I):

X~[~X2~ (1) I

, as hereinafter defined, which are of value in both human and veterinary medicine in enabling an increase in oxygen liberation from oxyhaemoglobin.

Human hemoglobins are composed of four palpated (glob in) chains which together comprise the hemoglobin tetramer; each chain surrounds a porphyrin molecule (hem) containing a central iron atom to which oxygen is reversibly bound. When a graph is plotted of the percentage saturation of hemoglobin with oxygen (ordinate) against the partial pressure of oxygen, sometimes called the oxygen tension (abscissa) a characteristic sigmoid curve is obtained, the oxygen-dissociation curve. A displacement of the curve to the left of the "normal" position would indicate an increase in the affinity for oxygen of the hemoglobin, a lower oxygen tension then being required to produce a given percentage saturation, while conversely a displacement to the fight would indicate a reduced oxygen affinity and hence a requirement for a higher oxygen tension for a given percentage saturation. It follows that upon displacement of the curve to the right there is a reduction in the percentage of oxyhaemoglobin present at any given oxygen tension and hence an increased liberation of oxygen upon a fall in tension to any given level.

The compounds of formula (I), as hereinafter defined, induce an in vitro right-displacement of the oxygen-dissociation curve a) of fresh whole human blood and b) of whole human blood subjected to a procedure (incubation overnight at 37C) producing changes similar to those seen in blood stored for extended periods by transfusion services and the like (vise infer).

MC/JAH/20th April.

I, .
. i The compounds thus have applications both in viva and in vitro in circumstances where it is desirable to provide a more effective delivery of oxygen to the tissues of the (eventual) recipient.

In viva applications for the compounds include the following, many of which may be together classed as the relief or amelioration of conditions wherein the delivery of oxygen to the tissues is impaired, i.e. wherein there is tissue hypoxia:
-the treatment of shock -the treatment of cardiac ischaemia,for example after myocardial 10 infarction (coronary thrombosis), and the relief of suckle thereto such as angina pocketers -the treatment of cerebral ischaemia and of cerebrovascular accidents in general -the relief of intermittent claudication -the treatment of placental insufficiency in graved females -the treatment of certain anemic conditions and in particular pathological anemia in preterm infants -the treatment of the micro vascular complications of diabetes Maltese -the treatment of hypovolaemic anemia of trauma (the so-called "missing blood syndrome") -as an adjunct to anesthesia in cardiac bypass surgery, in particular in patients having compromised respiration -applications in which a pathological tissue or invading organism is made more sensitive to treatment by increasing the partial pressure of oxygen in its environment, for example:

MC/JAH/20th April.

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_ 4 -the radio sensitization of tumors as an adjunct to deep X-ray therapy, with or without concomitant hyperbaric oxygen treatment, the treatment of infections of oxygen-sensitive parasites, for example, anaerobic bacteria.
Thus in one aspect of the invention there is provided a sterile, sealed vessel containing an anti-coagulant and a non-toxic amount of a tricyclic compound of formula (I), as defined above, or a pharmacologically acceptable salt thereof.
In a particular embodiment the sealed vessel contains human erythrocytes and effective amounts of the anti-coagulant and the non-toxic compound or salt.
In another aspect of the invention there is provided a method for maintaining the oxygen-delivery capacity of stored human erythrocytes in which the cells a admixed, prior to their transfusion into a recipient, with a non-toxic, maintenance-effective amount of the compound (I) or acceptable salt thereof.
In still another aspect of the invention there-is provided a method for prolonging the useful storage life of stored human erythrocytes which comprises admixing the cells prior to their transfusion into a recipient, with a non-toxic, prolongation-effective amount of the compound (I) or accept-able salt thereof.

aye - pa -A major in vitro application for the compounds is in the field of blood storage. As is well known there is an ever-present need for human blood by medical services throughout the world for use in a wide variety o, life-suppor-live measures. For the majority of recipients whole blood is the only accept table material as although a number of alternatives have been proposed, none has been found to be a completely satisfactory substitute. The collection, storage and distribution of blood is generally catered for by specialist trays-fusion services or blood banks" as exemplified by the National Blood Trays-fusion Service in the United Kingdom. The effective and economic operation 10 of such agencies is however in large measure governed by the fact that whole blood or, more correctly, the red blood cells (erythrocytes) therein, even when stored as customarily at 4C, have a very limited "shelf-life"
generally accepted as I days after removal from the donor By the end of this period they are considered unsuitable for transfusion and are discarded and there has been considerable research into methods for prolonging the useful life of stored red blood cells and thus reducing the wastage due to "out-dating".

A particular feature of the aging of red blood cells during storage is a progressive left-displacement of the oxygen-dissociation curve associated us with a fall in intracellular levels of 2,~-diphosphoglycerate (DUG), the earthier-~Z~93~4 cites' natural right-displacement effecter. As previously indicated a left-displacement is associated with the hemoglobin having an increased affinity for oxygen and hence aging cells exhibit a progressive decline in their ability to deliver oxygen to the peripheral tissues following transfusion. Although this property is gradually restored within the recipients body as DUG levels recover, the initial deficiency is of literally vital significance as the prime reason for transfusing red blood cells (as distinct from just plasma) is generally the immediate prevention or reversal of tissue hypoxia (vise swooper). The present compounds, in displacing the oxygen-dissociation curve to the right, are of value not only on maintaining the oxygen-delivery capacity of stored red blood cells, thus improving their quality and providing improved oxygen-delivery in the immediate post-transfusion period, but also in prolonging their useful storage life.

In formula (I), as set forth above, X is a carboxyl or 5-tetrazoLyl group X is carbonyl or ethylene X3 is hydroxyl or a group -X4(CnHzn)X5 where X is oxygen or Selfware X lo hydrogen or a group ox where X is hydrogen, alkanoyl of 1 to 4 carbon atoms or a group ~(CmH2m~X7 why X is hydrogen or a group - OX
where X is hydrogen or alkanoyl of 1 to 4 carbon atoms and ~2z~3~

m and n are each, independently, an integer from 1 to 4, together with salts thereof, provided that when X is a group ox then n is always greater than 1 and X4 and X5 are attached to different carbon atoms and that when X7 is a group ox then m is always greater than 1 and no single carbon atom in the radical -(C H )- it attached to two - m Em oxygen atoms.

As herein understood, the 5-tetrazolyl group us that having the structural formula .--' I
_ N

which thus embraces both tautomeric forms thereof respectively identi-liable as 5-/1H/ tetrazolyl and 5~/2H/-tetrazolyl~

When m and/or n is 3 or 4 the moieties -(CmH2m)- and -(C Ho Jo can be linear or branched.

In the salts of the compounds of formula tip the biological activity resides in the tricyclic (anion) moiety and the identity of the cation is of less importance although for use in medicine it is preferably pharmacologically acceptable to the eventual recipient Suitable salts include ammonium salts, alkali metal salts such as sodium and potassium salts, alkaline earth salts such as magnesium and calcium salts, and salts formed with organic bases, for example, ~2293~

amine salts derived from moo-, dip or troweler alkyd) or (lower alkanol)amines such as triethanolamine and diethylaminoethylamine, and salts with heterocyclic amine such as piperidine, pardon, piperazine and morpholine.

As a class of compounds within formula (I) may be mentioned those wherein:
x1 is a carboxyl or 5-tetrazolyl group X is carbonyl or ethylene X3 is hydroxyl or a group -X4~CnH2n)X5 where X us oxygen or Selfware X is hydrogen or a group ox why x6 is hydrogen or alkanoyl of 1 to 4 carbon atoms and n is an integer from 1 to 4, together with salts thereof, provided that when X is a group ox then n is always greater than 1 and X4 arid X are attached to different carbon atoms As subclasses of compounds within formula (I) may be mentioned those wherein:
(;) x1 is 5-tetrazolyl and salts thereof (j;) x2 is carbonyl (iii) X3 is a group -X4(CnH2 )X5 (iv) X is oxygen (v) X is hydrogen ~Z2~3~

(vi) X5 is a group ox where X is hydrogen, i.e. X5 is hydroxyl tvii) n is 2 or 3.

- Two further classes of compounds within formula (I) respectively comprise those wherein (a) X1 is 5-tetrazolyl, x2 is carbonyl and X3 us -O(CnH2n)H; and (by X1, x2 and X3 are as herein before defined, provided that X is other than -O(CnH2n)H when X1 and x2 are respectively 5 tetrazolyl and carbonyl;
together with salts thereof.

Preferred compounds within formula (I) are C2~50 chemically named 2-ethoxy-6-(5-tetrazolyl)xanthone, together with salts thereof, and on particular HO (SHEA 2 I;

O ~/~ N

NUN

~Zz93~!4 chemically named 2-(2-hydroxyethoxy)-6-(5-tetrazolyL)xanthone, together with salts thereof Where the compounds of formula (I), as above defined, include an asymmetric center the said formula should be understood to include all optical isomers embraced thereby and mixtures thereof.

The compounds of formula (I) and their salts may be prepared by those methods known in the art for the synthesis of compounds of analogous structure and in thus regard reference is made by way of illustration only, to the following standard texts:-(i) "Protective Groups in Organic Chemistry" Ed JAW McOmie,Plenum Press (1973), ISBN 0-306-30717-0;
(ii) "Compendium of Organic Synthetic Methods" Ed IT. Harrison and S. Harrison, Wiley-Interscience, Vol. I ~1971) IS8N 0-471-35550-X, Vol. II (1974~IS8N 0-471-35551-8 and Vol. III ted. LO Hegedus and L. Wade) (1977) ISBN 0-471-36752-4; and (iii) Rhodes "Chemistry of Carbon Compounds" second edition, Elsevier Publishing Company.

/

/

~L2~2~3~
. . 'I

(1) One method, applicable to both the xanthenes (X2 is ethylene) and the xanthones (X2 is carbonyl) within formula (I), comprises cyclization 5 in the presence of a base of a compound of formula (II) ~3~,~x2~ (If) wherein X1, x2 and X3 are as defined in formula (I) and one of z1 and z2 is hydroxyl or an ester thereof and the other is a leaving atom or group.

Amongst suitable leaving atoms/groups are halo (for example sheller), vitro and sulphinyl while appropriate bases include alkali metal alkoxides 10 such as sodium rnethoxide and sodium ethoxide.

(2) The xanthones may also be prepared by cyclization in the presence of a Lewis or pro tonic acid of a compound of formula (III) Lowe X~lx l (III) MC/JAH/20th April.

I
1 .

wherein X1 and X3 are as defined in formula (I) and I is a carboxyl group, a derivative thereof or a formal group.

Suitable identities for Z3 as carboxyl group derivatives include cyan, carbamyl and chlorocarbonyl. Suitable Lewis acids include aluminum tracheal ride, ferris chloride, phosphorus oxychloride and boron trifluoride while preferred pro tonic acids are polyphosphoric (tetraphosphoric) and sulfuric acids. The reaction is preferably effected at a temperature in the range 20 to 160C.

(3) A further preparation of the xanthones comprises selective oxidation of the corresponding xanthene also within formula (I).

A suitable selective oxidizing agent comprises oxygen in the presence of Briton B (tetramethylammonium hydroxide) and pardon.

(4) Conversely, the xanthenes may be prepared by selective reduction of the corresponding xanthone within formula (1).

Suitable selective reducing agents include zinc and an acid, for example acetic or hydrochloric acid and zinc amalgam and concentrated hydrochloric acid (the Clemmensen reduction).

(5) The compounds of formula (I? wherein X1 is 5-tetrazolyl may be prepared by the reaction with hydrazoic acid or a salt thereof or with nitrous acid, as appropriate, of a compound of formula (IV) My jJAH/2ûth April ^ trade Mark ~LZZ~3~

OX

Z

wherein x2 and I are as defined in formula (I) and Z4 is a 5-tetrazolyl group precursor as herein defined.

When hydrazoic acid or a salt thereof is employed the 5-tetrazolyl group precursor is a group of formula --C = N

wherein Z5 and z6 together form a bond (nitrite), Z5 is hydrogen or alkyd of 1 to 4 carbon atoms and z6 is alkoxy of 1 to 6 carbon atoms (imidoester), alkylthio of 1 to 6 carbon atoms (imidothioester), hydrazino (amidrazone), or amino (amidine) or Z5 is hydroxyl and z6 is amino (amidoxime). The reaction is desirably effected in a polar aprotic liquid medium, for example lo dimethylsulphoxide, dimethylformamide, hexamethylphosphoramide, dimethylace-tumid, N-methyl-2-pyrrolidone, sulpholane and acetonitrile and mixtures thereof, and preferably with a hydrazoic acid salt such as sodium or ammonium a ides MC/JAH/20th April.

.

3~4 When nitrous acid is employed the 5-tetrazolyl group precursor is also a group of formula -- C _ N
z6 z5 wherein Z5 is hydrogen or alkyd of 1 to 4 carbon atoms and ;z6 is hydrazino ~amidrazone), or Z5 is hydrogen and z6 is amino (amidine). In the latter case selective reduction of the initially formed notarization product, with or without prior isolation and using an agent such as sodium amalgam, is required to provide the 5-tetrazolyl end product.

(6) The compounds of formula (I) wherein X1 is carboxyl may be prepared by hydrolysis of a compound of formula (V) Zoo (V) wherein x2 and X3 are as defined in formula (I) and Z7 is a carboxyl group precursor as herein defined.

Suitable identities for Z7 include cyan, trichloromethyl and a group Casey where z8 is a leaving, preferably nucleophilic atom or group such as halo, trichloromethyl, alkoxy of 1 to 6 carbon atoms and optionally-substi-tuned amino.

MC/JAH/20th April.

~2~3~
.

The hydrolysis may be effected by heating with either a dilute aqueous mineral acid, for example sulfuric or hydrochloric acid, optionally in the presence of an organic acid such as acetic acid, or with a base such as an alkali metal hydroxide or alkoxide, for example aqueous sodium or potassium 5 hydroxide, sodium methoxide and sodium ethoxide.

It will be appreciated that the basic conditions appropriate to cyclization of a compound of formula (II) (vise (1) swooper) will also effect hydrolysis of a group Z7 as defined in formula (V) and that the former synthetic approach may hence be extended to include, where necessary, a combined ("one-pot") 10 cyclization/hydrolysis procedure. The starting material for method (1) may thus more generally be represented by formula (Ill) I x I (ha) z2 z1 ye wherein x2 and X3 are as defined in formula (I), one of z1 and z2 is hydroxyl or an ester thereof and the other is a leaving atom or group and ye is a group X1 as defined in formula (I) or a carboxyl group precursor as herein 15 defined.

to) The carboxyl compounds of formula (I) may also be prepared by selective oxidation of a compound of formula (VI) My H/2ûth April.

, .

2 2 I 3 I!
`- X2 lo TV

wherein x2 and X3 are as defined in formula (I) and Z9 is alkyd or alkanoyl of 1 to 6 carbon atoms.

Alkyd identities for Z may be oxidized with agents such as acid or alkaline aqueous potassium permanganate, an aqueous dichromate salt such 5 as sodium or potassium dichromate in the presence of acetic acid, oxygen in the presence of a catalyst such as a cobalt, manganese or vanadium salt or oxide and chromium trioxides with for example acetic or sulfuric acid while oxidation of an alkanoyl group may be effected by means of an agent such as nitric acid, an aqueous dichromate salt such as sodium or potassium dichromate in the presence of acetic acid, an aqueous salt of hypobromous or hypochlorous acid in the presence of a base and chromium trioxides with for example acetic or sulfuric acid.

It will be appreciated that the formation in this manner of the carboxyl identity for X1 may, if desired, be effected in association with the conversion 15 of a xanthene precursor to a xanthone end-product (vise (3) eye) the two procedures being conducted either sequentially or simultaneously (as a "one-pot" reaction) depending upon the identity of the selective oxidizing agent(s) employed The starting material for the oxidative preparation of the compounds ox formula (I) may thus generally be represented by formula 20 (VII) MC/JAH/20th April.

l~Z~3~
(Ill) wherein x2 and X3 are as defined in formula (I) and ye is a group Al as defined in formula (I) or alkyd or alkanoyl of 1 to 6 carbon atoms, provided that when x2 is carbonyl then ye is always alkyd or alkanoyl.

(8) The carboxyl xanthenes of formula (I), i.e. where X1 is carboxyl and 5 x2 is rnethylene, may be prepared by carooxylation of a compound of formula (VIII) X Jo SHEA
¦ O I I O ¦ (VIII) ._ . , wherein X3 is as defined in formula (I) and zoo is halo, preferably broom or idea.

This may be effected by for example reacting the compound (VIII) 10 in ethereal solution with either lithium or magnesium, in the latter case to yield the appropriate Grignard reagent, and then contacting the mixture with gaseous or solid carbon dioxide.

(9) A further synthetic approach comprises conversion of a compound of formula (IX) MC/OAH/20th April.

I

I Al (IX) wherein X1 and x2 are as defined in formula (I) and z11 is a group convertible to a group X also as defined in formula I).

Compounds wherein X3 is hydroxyl may be prepared by hydrolysis of a suitable precursor, for example by reaction with water of a corresponding diazonium salt (Z11 is -NOAH where W is an anion such as chloride, bromide and hydrogen sulfite), the latter being prepared by the action of nitrous acid on the amine (Z11 is amino). The diazonium salts may also be converted to the corresponding alkylthio end-products (wherein X4 is Selfware and X5 is hydrogen) by reaction with an appropriate potassium alkyd xanthate and sequential decomposition of the successively formed diazoxanthate and aromatic xanthate by warming in a faintly acidic cuprous medium (the Lockhart synthesis). The alkylthio compounds may also be prepared by alkylation of the corresponding they'll (Z11 is Marquette) which may be obtainedby for example alkaline hydrolysis of the previously mentioned aromatic xanthates.

The hydroxyl compounds may also be prepared from precursors having as z11 a group ooze which is convertible to hydroxyl. Suitable identities for the moiety z12 include alkyd, for example alkyd of 1 to 4 carbon atoms and in particular methyl, ethyl, isopropyl and t-butyl; aralkyl such as bouncily;
azalea such as alkanoyl, in particular alkanoyl of 1 to 6 carbon atoms, for MC/JAH/20th April.

. I

- example acutely; and tetrahydropyranyl. Such groups may be removed, i.e.
replaced by hydrogen, by methods standard in the art. Thus removal of an alkyd group may be effected using for example magnesium iodide or sodium thiocresolate, by heating with aluminum trichloride in zillion or (at reduced temperatures) by use of an agent such as boron trichloride or tribromide in a medium such as dichloromethane; an azalea group may be removed by base hydrolysis; an alkyd group and tetrahydropyranyl may be removed by acid hydrolysis, for example using hydrogen bromide in acetic acid; and hydrogenolysis (for example using a palladium charcoal catalyst) may be used to remove an aralkyl group.

It will be appreciated that certain of the above-described conditions for removal of an alkyd group will also be suitable for effecting cyclization as described in (2) swooper and that hence the hydroxyl xanthones of formula (I) may be prepared by a "one pot" cyclization/dealkylation of the alkoxy compounds of formula (III) (wherein X4 is oxygen and X5 is hydrogen).

Alkoxy compounds may be prepared by alkylation of the corresponding hydroxyl compound, for example by use of an alkyd halide or dialkyl sulfite and an alkali such as an alkali metal hydrides or carbonate.

The hydroxyl compounds may be converted to the corresponding hydroxy-alkoxy compounds (wherein X4 is oxygen and X5 is hydroxyl) by for example reaction with the appropriate alkaline oxide or carbonate and the hydroxy-alkylthio compounds (wherein X4 is Selfware and X5 is hydroxyl) may be similarly prepared from the corresponding they'll ~Z11 is Marquette); when in the said starting materials X1 is carboxyl the latter group may be simultaneously MC/JAH/20th April.

I
to esterified by this procedure, the desired end-product then being obtained by selective hydrolysis thereof (vise (6) swooper). The end-products wherein X5 is alkanoyloxy (i.e. x6 is alkanoyl) may be prepared from the corresponding hydroxyalkoxy or hydroxyalkylthio compounds, as appropriate, by conventional 5 alkanoylation procedures and the latter may be obtained by hydrolysis of the former.

In the preparation of the compounds of formula (I) by the above-described methods it will be understood that where the groups X1 and X3 are formed prior to the complete formation of the desired end-product it may in some instances be desirable to protect said groups from reaction in the final synthetic step(s), and subsequently regenerate them by appropriate deprotection procedures, using techniques well known in the art; alternatively the formation of X1/X3 may advantageously comprise the final step in the synthetic sequence.

The compounds of formula (I) may be isolated as the acids or as salts thereof and it will be appreciated that the said acids may be converted to salts thereof, and the reverse, and the salts converted to salts formed with other cations, by techniques well-known and conventional in the art.
Thus, those salts which are not themselves pharmacologically acceptable are of value in the preparation of the parent carboxyl or 5-tetrazolyl acids and of pharmacologically acceptable salts thereof.

When the preparative procedures herein described provide a mixture of optical or other isomers of a compound of formula (I) or of an intermediate thereto, the individual isomers may be separated by appropriate conventional techniques.

MC/JAH/20th April.

.

293~

The compounds the formula (I), as above defined, may be used in both human and veterinary medicine in circumstances such as those previously identified where it is desirable to provide a more effective delivery of oxygen to the tissues of the (eventual) recipient. When administered in viva the compounds may be used both on a regular maintenance basis and for the relief or amelioration of acute crisis states.

For in viva use the compounds may be administered to the human or non-human recipient by a route selected from oral, parenteral (including subcutaneous, intradermal, intramuscular and intravenous) and rectal.
The size of an effective dose of a compound will depend upon a number of factors including the identity of the recipient, the precise condition to be treated and its severity and the route of administration and will multi-mutely be at the discretion of the attendant physician or veterinarian.
An effective dose will generally be in the range 1 to 500 mg/kg Baudot of recipient per day, more generally in the range 10 to 250 mg/kg Baudot per day and most often in the range 25 to 100 mg/kg Baudot per day, a particularly suitable dose being 50 mg/kg Baudot per day (all doses calculated as the carboxyl or 5-tetrazolyl acid of formula (I); for salts the figures would be adjusted proportionately). The desired dose is preferably presented as between two and four sub-doses administered at appropriate intervals throughout the day. Thus where two sub-doses are employed each will generally be in the range 0.5 to 250, more generally 5 to 125 and most often 12.5 to 50 my (acid)/kg Baudot with an optimum of 25 my (acid)/kg Baudot.

MC/JAH/20th April.

~2~3~
Al A daily dose for a human being weighing of the order of 50 kg will thus generally be in the range 50mg to 259 (acid), more generally in the range 500 my to 12.59 (acid) and most often in the range 1.259 to 59 (acid) and may be conveniently presented as two equal unit sub doses of 25mg to 12.59 (acid), more generally 250mg to 6.259 (acid) and most often 0.6259 to 2.59 (acid). Optimally a human daily dose is 2.59 (acid) conveniently presented as two unit sub-doses each of 1.259 (acid). For veterinary use, for example in the treatment of non-human mammals such as cats, dogs, cattle, sheep, pigs and horses, the above-recited doses would be increased or decreased at the discretion of the veterinarian having regard to the weight and identity of the recipient.

While it is possible for the compounds of formula (I) to be administered as the raw chemical it is preferable to present them as a pharmaceutical formulation preparation. The formulations of the present invention, for human or for veterinary use, comprise a compound of formula (I), as above defined, together with one or more acceptable carriers therefore and optionally other therapeutic ingredients. The carrier(s) must be 'acceptable' in the sense of being compatible with the other ingredients of the formulation and not deleterious to the recipient thereof.

:20 The formulations include those suitable for oral, parenteral (including subcutaneous, intradermal, intramuscular and intravenous) and rectal ad minis-traction although the most suitable route may depend upon for example the condition and identity of the recipient. The formulations may conveniently be presented in unit dosage form and may be prepared by any of the methods well known in the art of pharmacy. All methods include the step of bringing into ask- ration the compound of formula (I) (the active ingredient) with MC/JAH/2ûth April.

93~
.

the carrier which constitutes one or more accessory ingredients. In general the formulations are prepared by uniformly and intimately bringing into association the active ingredient with liquid carriers or finely divided solid carriers or both, and then, if necessary, shaping the product into the desired 5 formulation.

Formulations of the present invention suitable for oral administration may be presented as discrete units such as capsules, cachets or tablets each containing a predetermined amount of the active ingredient; as a powder or granules; as a solution or a suspension in an aqueous liquid or a non-aqueous 10 liquid; or as an oil-in-water liquid emulsion or a water-in-oil liquid emulsion.
The active ingredient may also be presented as a bonus, elixir or paste.

A tablet may be made by compression or mounding, optionally with one or more accessory ingredients. Compressed tablets may be prepared -- by compressing in a suitable machine the active ingredient in a free-flowing 15 form such as a powder or granules, optionally mixed with a binder, lubricant, inert delineate, lubricating, surface active or dispersing agent. Mpulc'ed tablets may be made by mounding in a suitable machine a mixture of the powdered compound moistened with an inert liquid delineate. The tablets may optionally be coated or scored and may be formulated so as to provide slow or controlled f70 release of the active ingredient therein.

Formulations for parenteral administration include aqueous and non-aqueous sterile injection solutions which may contain anti-oxidants, buffers, bacteria-stats and solutes which render the formulation isotonic with the blood of the intended recipient; and aqueous and non-aqueous sterile suspensions MC/JAH120th April,lg82.

which may include suspending agents and thickening agents. The formulations may be presented in unit-dose or multi-dose containers, for example sealed ampules and vials, and may be stored in a freeze-dried (Iyophilized) condition requiring only the addition of the sterile liquid carrier, for example water for injections, immediately prior to use. Extemporaneous injection solutions and suspensions may be prepared from sterile powders, granules and tablets of the kind previously described.

Formulations for rectal administration may be presented as a suppository will the usual carriers such as cocoa butter and polyethylene glycol.

Preferred unit dosage formulations are those containing a daily dose or unit daily sub-dose, as hereinabove recited, or an appropriate fraction thereof, of a compound of formula (I).

-- It should be understood that in addition to the ingredients particularly mentioned above the formulations of this invention may include other agents conventional in the art having regard to the type of formulation in question, for example those suitable for oral administration may include flavoring agents.

The compounds of formula (I) may also be presented as depot formulations of the kind known in the art from which the active ingredient is released, over a prolonged period, once the formulation is in place within the body of the recipient.

MC/~AH/20th April.

- I

A further application for the compounds of formula (I) is the extractor-portal treatment of blood from the (generally human) patient. As one possibility such treatment may be conducted in a batch-wise manner by removing an appropriate volume of blood, admixing it with the compound and transfusing the treated blood back into the patient. As an alternative possibility the treatment may be on a continuous basis, analogous to the well-known tech-piques for haemodialysis, whereby for a period of time blood is continuously withdrawn admixed with the compound and passed back into the patient.

Both procedures should be conducted under sterile conditions and may be repeated as often as necessary. An effective blood concentration of a compound of formula (I) will generally be in the range 0.1 my to 50 my, more generally in the range û.5 my to 25 my and most often in the range 1 my to 10 my, with an optimum concentration of 3 my.
.

For in vitro use in the storage of red blood cells as previously described 15 the compounds are conveniently admixed with the cells in the vessel in which the latter are collected and stored; this conventionally takes the form of a bottle or bag of sufficient size to hold the customary whole blood unit (circa 450 ml.) together with an Alcott of anticoagulant. A compound may be brought into contact with the cells at any appropriate point between 20 their collection from the donor and their transfusion (together with the compound) into the recipient. As one possibility therefore the compound, in association with the anticoagulant, is present within the bottle or bag when the latter is "ready for use", the admixture occurring upon entry of the blood, while in an alternative approach the compound is added to cells 25 already held within the bottle/bag, for example immediately subsequent to collection or just prior to use transfusion). The compounds may be used MC/JAH/20th April.

~22~33~9~

in Lucy fashion whether the cells are stored in the form of whole blood or as a packed cell mass (when the plasma is held separately) and, in the latter case, whether transfused resuspended in plasma or in a plasma substitute.

The effective concentration of a compound, in whole blood volume in a bottle or bag as above described, will generally be in the range 0.1 my to 50 my, more generally in the range 0.5 my to I my and most often in the range 1 my to 10 rum, with an optimum concentration of 3 my.
Although the precise weight of compound required will vary with its identity a standard size bottle/bag tide swooper) will require circa 0.59 (calculated 10 as the acid) to provide the optimum 3 my concentration.

The compounds of formulae (II) to (IX) as herein before defined may be-prepared by those methods known in the art for the synthesis of compounds of analogous structure and in particular, inter alias by methods analogous to those taught herein in respect of the compounds of formula (I) using 20 appropriate starting materials and conditions as herein before described.

It will be understood from the foregoing description that this invention may comprise any novel feature described herein, principally but not exclusively f r example:

(a) Compounds of formula (I) as herein before defined and salts thereof.

(b) Methods as herein before described for the preparation of compounds according to (a) eye, together with the compounds when so prepared.

(c) Compounds of formula (I) as hereinoefore defined and pharmacologic gaily acceptable salts thereof for use in the medical treatment of a mammal and in particular a human being.

MC/JAH/20th April.

aye Al, (d) Compounds of formula (I) as hereinbeFore defined and pharmacologic gaily acceptable salts thereof for use in a mammal, in particular a human being, to provide a more effective delivery of oxygen to the tissues.

(e) Compounds of formula (I) as herein before defined and pharmacologic gaily acceptable salts thereof for use in a mammal, in particular a human being, in the relief of tissue hypoxia.

(f) A pharmaceutical formulation comprising a treatment-effective amount of a compound of formula (I) as herein before defined or a pharmacolo-jackal acceptable salt thereof together with an acceptable carrier therefore (9) A method for the preparation of a formulation according to (f) - eye comprising admixture of the active ingredient, as defined, with the carrier therefore (h) A method for providing a more effective delivery of oxygen to the tissues of a mammal, in particular a human being, comprising administering to a mammal in need thereof a non-toxic, treatment-effective amount of a compound of formula (I) as herein before defined or a pharmacologically acceptable salt thereof.

(i) A method for the relief of tissue hypoxia in a mammal, in particular a human being, comprising administering to a mammal in need thereof a non-toxic, treatment-effective amount of a compound of formula (I) as herein before defined or a pharmacologically acceptable salt thereof.

(j) A method for maintaining the oxygen-delivery capacity of stored mammalian red blood cells comprising admixing said cells, prior to their MC/J~H/2ûth April.

~ZZ~3~4 transfusion into a recipient mammal, with a non-toxic, maintenance-effective amount of a compound of formula (I) as herein before defined or a pharmacologic gaily acceptable salt thereof.

(k) A method for prolonging the useful storage life of stored mammalian red blood cells comprising admixing said cells, prior to their transfusion into a recipient mammal, with a non-toxic, prolongation-effective amount of a compound of formula (I) as herein before defined or a pharmacologically acceptable salt thereof.

(l) A method according to (j) or (k) swooper wherein the red blood cells are human in origin.

(m) A sterile, sealed vessel containing an anticoagulant and a non-toxic amount of a compound of formula (I) as herein before defined or a pharmacologic gaily acceptable salt thereof.

(n) A sterile, sealed vessel containing mammalian, in particular human, red blood cells, an effective amount of an anticoagulant and a non-toxic amount of a compound of formula (I) as herein before defined or a pharmacologic gaily acceptable salt thereof.

(o) Novel compounds of formulae (II) to (IX) as herein before defined, methods for their preparation as herein before described and the compounds when so prepared.

MC/JAH/20th April.

I

A large number of tricyclic structures have been described in the literature as active in mammals and in in vitro mammalian preparations as inhibitors of allergic reactions associated with reagin;c antibodies of the kind responsible for asthma in man, see for example Wok. patent spec;f;cat;ons nos. 1,414,621; 1,447,031;
1,447,032; 1,452,891; 1,458,185 and 1,458,186; such compounds have thus been proposed for use in the treatment or prophylax;s of mammalian allergic conditions such as asthma and other allergic chest conditions, hay fever (allergic runts conjunctivitis, urticaria and eczema.

Formula (I) as herein defined is believed to lie outside of the disclosures of all this art.

Japanese patent Cook no. 16821/82 (laid open to public inspection on Thea January 1982) describes a drug for treating ;mmunodeficiency diseases of mammals, e.g. man, comprising, as an effective ingredient, a compound represented by general formula:

wherein R represents a hydrogen atom or a lower alkoxy group and A
represents an oxygen atom or a sulfonyl group, or a salt thereof;
specifically recited immunodefic;ency diseases are cancer, rheumatism, ~93~4 clue auto immune disease, hepatitis nephritis and infectious disease.

The Japanese document identifies only three specific compounds within the general formula therein set forth, each said compound being acknowledged as previously disclosed in the literature and suggested for use in the treatment or prophyLaxis of asthma and related allergic conditions. These three compounds are:
(A): 3-(1H-tetrazol-5-yl)thioxanthone-10,10-dioxide (B): 7-methoxy-2-(1H-tetrazol-5-yl)xanthone (C): 2-(1H-tetrazol-5-yl)xanthone.

The Japanese document thus identifies no specific compound that was not previously specifically disclosed in the literature and the subject invention-is presented-a's'the''finding of a "new use" for the said "old" compounds.

None of the compounds identified in the Japanese document as (A), tub and (C) is within formula (I) as herein defined The following Examples are provided in illustration of the present invention and should not be construed as in any way constituting a limitation thereof. All temperatures are in degrees Celsius.

. ` . I

Example 1

7-Methoxyxanthone-3-carboxylic acid A. 2-(4-Methoxyphenoxy)terephthalic acid Sodium metal (11.5 9) was dissolved in methanol (250 ml) and to this solution was added 4-methoxyphenol (62.1 g). The methanol was thoroughly removed by rotary evaporation and the residual sodium salt dissolved in dim ethyl sulphoxide. Dim ethyl 2-nitroterephthalate (107.6 9) was added and the mixtul~ stirred and heated at 120 for 2.5 h. The dark resulting solution was hydrolyzed by boiling under reflex with a solution of sodium hydroxide pellets (70 9) in water (500 ml) and ethanol (800 ml) for 2.5 h. The solution was acidified by pouring into excess iced hydrochloric acid and the precipitated 2-(4-methoxyphenoxy~terephthalic acid was filtered off, washed with water and dried at 90 in vacua to give 125.0 9, mop. 280~283.
The following compounds were prepared similarly:
2~4-Ethoxyphenoxy)terephthalic acid, mop. 280-281 from 4-ethoxyphenol prepared by the method of McElvain and Englehardt, _. Amer. Chum. So., (19~ 66, 1080.
2-(4-Propoxyphenoxy)terephthalic acid, mop. 279-281 from 4-propoxyphenol prepared by the method of Klarmann7 Guts and Shternov, J.
Amer. Chum. Sock (1932), 54, 298.
2-(4-lsopropoxyphenoxy)terephthalic acid, mop. 261-263, from acetic acid, from 4-isopropoxyphenol prepared by the method of Klarmann, Guts and Shternov, J. Amer. Chum. Sock (1932), 54, 298.
2-(4-Methylthiophenoxy)terephthalic acid mop. 294-296 from methanol, from 4-(methylthio)phenol.
B. 7-Methoxyxanthone-3-carboxylic acid 2-(4-Methoxyphenoxy)terephthalic acid (90.0 9) was boiled under reflex with phosphorus oxychloride (900 ml) far 2 h. The cooled reaction mixture was IvlC/JAH/21st April.

31 ~Z~5~3~

cautiously decomposed by adding to water, controlling the temperature at 40-50 by ice addition. The precipitated 7-methoxyxanthone-3-carboxylic arid was filtered o if, washed with water, and recrystallized from dimethylformamide (after drying at 80 in vacua mop. 301-302).
Found: C, 66.73%; H, 3.70%. C15H1005 requires C, 66.67%; H, 3.73%.
The following compounds were prepared similarly:
E 7-Ethoxyxanthone-3-carboxylic acid mop. 286-289 ~unrecrystallised).
Ex.3: 7-Propoxyxanthone-3-carboxylic acid mop. 261-264 from dimethylformamide.
Found I 68.84%; H, 4.91%. C17H1405 requires C, 68.46%; H, 4.70%.
Ex.4: 7-(Methylthio)xanthone-3-carboxylic acid mop. 272-275 from acetic acid.

.
Found: C, 62.69%; H, 3.48%; S, 11.15%. C15H10045 requires C, Dow;

H, 3.4~%; S, 11.19%.

Example 5 7-Isopropoxyxanthone-3-carboxylic acid .
2-~4-Isopropoxyphenoxy)terephthalic acid (1305 9) was boiled under reflex with thinly chloride for 0.5 h, then ferris chloride (1.0 g) was added and reflex continued for a further 4.5 h. The excess thinly chloride was evaporated off, and the residue poured into water. The precipitated product was filtered off, washed with water, and stirred with excess aqueous sodium bicarbonate solution at 80-90 for 1.5 h. The solution was acidified to precipitate 7-isopropoxyxanthone-3-carboxylic acid which was filtered off, washed with water and dried. It was recrystallized first from dimethylformamide, and then from acetic acid, mop. 261-263.

Found: C, EYE%; Ho 4.60%. C17H1405 requires C, 68.46%; H, 4.70/~.

MC/JAH/21st April.

3 ~2~3~

Example 6 7-Hydroxyxanthone-3-carboxylic acid 7-Methoxyxanthone-3-carboxylic acid (8.0 9) was boiled under reflex with a 12% solution of hydrogen bromide in acetic acid (500 ml) for 28 h. The reaction mixture was poured into iced water and the precipitated product filtered off, washed well with water, and dried at 100 in vacua to yield 7-hydroxyxanthone-3-carboxylic acid mop. 349-350.
Found: C, 65.59%; H, ~.14%. C14H805 requires C, 65.63%; H, 3.12%.

Exam mule 7 7-Ethoxyxanthone-3-carboxylic acid (i) 7-Hydroxyxanthone-3-carboxylic acid (5.0 9) was stirred with a mixture of an hydrous potassium carbonate (50 9) and deathly sulfite (10.25 ml;
1200 9) in dimethylformamide (150 ml) for 5 h, then allowed to stand at room temperature for 16 h. The reaction mixture was poured into water and the residual ethyl ester of 7-ethoxyxanthone-3-carboxylic acid filtered off and hydrolyzed by boiling with a solution of sodium hydroxide (2.0 9) in water (200 ml) and ethanol (50 ml) for 2 h. The cooled reaction mixture was acidified with excess hydrochloric acid, and the precipitated acid filters off, washed with water, and recrystallized from dimethylformamide mop. 287-289.
Found: C, 67.72%; H, 4.40%. C16H1205 requires C, 67-60%; H, 4.26%.
(ii) (A) Methyl 7-hydroxyxanthone-3-carboxylate 7-Hydraxyxanthone-3-carboxylic acid (10.0 9) was boiled under reflex with methanol (1.5 Iitres) and concentrated sulfuric acid (15 my for 3 h. The hot ~nlution was filtered, and on cooling methyl 7-hydroxyxanthone-3-carboxylate crystallized out, and was filtered off and dried, 6.4 g, mop. 268-270.

MC/JAH/21st April.

33 ~22~3~

(if) (B) 7-Ethoxyxanthone-3-carboxylic acid Methyl 7-hydroxyxanthone-3-carboxylate (6.9 9) was boiled under reflex with stirring with ethyl iodide (9.75 9), potassium carbonate (75 9) and acetone (I lithe) for 4 h. The mixture was filtered while hot and the residue itched with acetone. The combined filtrate and washings were evaporated to dryness and the residue dissolved in dichloromethane and washed with water. The solution was dried and evaporated to give methyl 7-ethoxyxanthone-3-carboxylate, 3.65 9, mop. 169-171.
The ester (3.6 9) was hydrolyzed by boiling with a solution of sodium hydroxide (2.0 9) in water (250 ml) and ethanol (50 ml) For 2 h. The resulting solution was acidified with excess dilute hydrochloric acid, and the precipitated product filtered off giving 7-ethoxyxanthone-3-carboxylic acid (on recryst-Alsatian from dimethylformamide mop. 290-291).
Similarly were prepared:
Ex.8: 7-(3-Hydroxypropoxy)xanthone-3-carboxylic acid mop. 245-246 from acetic acid, from 3-bromo-1-propanol (methyl ester, mop. 161-162 from methanol).
Found: C, 65.15%; H, 4.56%. C17H1406 requires C, 64.97%; H, 4.49%.
Ex.9: 7-Butox~xanthone-3-carboxylic acid mop. 225-227.
Found: C, 69.09%; H, 5.16%. C18H1605 requires C, 69.22%; H, 5.11%.
Ex.10: 7-Propoxyxanthone-3-carboxylic acid mop. 262-263, from n-propyl iodide (methyl ester, mop. 151-152).

Example 11 7-(2-Hydroxyethoxy)xanthone-3-carboxylic acid 7-Hydroxyxanthone-3-carboxylic acid (3.0 9), ethylene carbonate (13.0 9) and tetramethylammonium iodide (0.07 9) were heated together at 170 for oh.
The cooled reaction mixture was diluted with chloroform and the solid residue filtered off and boiled with a solution of sodium hydroxide (2.0 9) in MC/JAH/21st April,lg82.

I

ethanol (40 ml) and water (60 ml) for 5 h. The reaction mixture was then diluted with water, filtered, and acidified with dilute hydrochloric acid, and the solid product filtered off and recrystallized from boiling dimethylformamide to yield 7-(2-hydroxyethDxy)xanthone-3-carboxylic acid mop. 265-267.
Found: C, 63.43%; H, 4.11%. C16H1206 requires C, 64.00%; H, 4.03%.

Example 12 7-(2-Hydroxypropoxy)xanthone-3-carboxylic acid Methyl 7-hydroxyxanthone-3-carboxylate (2.0 9), propylene carbonate (Lowe) and tetramethylammonium iodide (0.20 9) were heated together at 170 for 4 h. The cooled reaction mixture was then boiled under reflex with a solution of sodium hydroxide (6.0 9) in water (200 ml) and ethanol (200 ml) for 30 min. The solution was cooled, filtered, and acidified with excess dilute hydrochloric acid. The precipitated product was filtered off, washed with water, and reorystallised twice from 95% 2-butanone-5% water mixture to yield 7-(2-hydroxy-propoxy)xanthone-3-carboxylic acid m p. structure confirmed by proton magnetic resonance spectroscopy).
Found: C, 65.06%; H, 4.54%. C17H1406 requires C, 64.96%; H, YO-YO%.

Example 13 7-(3-Acetoxypropoxy)xanthone-3-carboxylic acid 7-(3-Hydroxypropoxy)xanthone-3-carboxylic acid (8.8 9) was boiled under reflex with acetic android (200 ml) for 2 h. The resulting solution was filtered and the excess android evaporated off. The residual solid was washed with water and dried, then recrystallized from acetic acid to give 7-(3-acetoxy-propoxy)xanthone-3-carboxylic acid, mop. 236-237.

Found: C, 63.94%; H, 4.51%. ClgH1607 requires C, 64.04%; H, 4 53D/~.

MC/JAH/~lst April.

it US

Exam mule 14 7-Methoxy-3-(5-Tetraz olyl)xanthone (A) 7-Methoxyxanthone-~-carboxamide.
7-Methoxyxanthone-3-carboxylic acid (2n.0 g) was boiled under reflex with thinly chloride t200 ml) for 2 h. The excess thinly chloride was evaporated thoroughly from the solution and the residual acid chloride added to 0.880 ammonia (200 ml3 with stirring The solid 7-methoxyxanthone-3-carboxamide was filtered off, washed with water, and dried at 80 in vacua to give 19.6 9 mop. 2B6-287.
The following asides were prepared similarly:
7^Ethoxyxanthone-3-carboxamide, mop. 311-~14.
7-Butoxyxanthone-3-carboxamide, mop. 222-225.
7-(3-Acetoxypropoxy)xanthone-3-carboxamide, mop. 205-209.
7-(2-Acetoxypropoxy)xanthone-3-carboxamide, mop. 196-198 from acetic acid.
7-Propoxyxanthone-3-carboxamide, m.p.-272-274.
7-Isopropoxyxanthone-3-carboxamide, mop. 234-239.
7-(Methylthio)xanthone-3-carboxamide, mop. 228-234.
(B) 6 Cyano-2-methoxyxanthone.
7-Methoxyxanthone-3-carboxamide (1.15 9) was added to a stirred solution of thinly chloride (5.0 ml) in dimethylformamide t25 ml) at 0-5 over about 5 minutes. The reaction mixture was stirred at 0-5 for 1 h., then poured on to ice. The solid precipitated product was filtered off, washed with water and recrystallized from dimethylformamide, giving 6-cyano-2-methoxyxanthone, 0.60 9, mop. 254-255.
The following nitrites were prepared similarly:
-Cyano-2-ethoxyxanthone, mop. 204-205, ox dimethylfolmamide.
2-Butoxy-6-cyanoxanthone, mop. 156-157 ox acetic acid.

MC/JAH/21st April.

~2~3 AL

- 2-(3-Acetoxypropoxy)-6-cyanoxanthone, mop. 158-160 ox ethanol.
2-(2-Acetoxypropoxy)-6-cyanoxanthone, mop 139-140 ox methanol.
6-Cyano-2-propoxyxanthone, mop. 166-167 ox dimethylformamide.
6-Cyano-2-isopropoxyxanthone, mop. 145-146 ox aqueous dimethylformamide.
6-Cyano-2-(methylthio)xanthone, mop. 209-210 ox aqueous dimethylformamide.

(C) 2-Methoxy-6-(5-tetrazolyl)xanthone.
6-Cyano-2-methoxyxanthone (12.6 9) was heated with sodium aside ~3.41 g) and ammonium chloride (2.95 9) in dimethylformamide (100 ml) at 125 for 6 h. The reaction mixture was diluted with water and acidified with excess hydrochloric acid. The precipitated 2-methoxy-6-(5-tetra7O1yl)xanthone was filtered off, washed with water, and recrystallized from dimethylformamide, decomposes above 300.
- Found: C, 60.82%; H, 3.45%; N, 18.91%.
Clown requires C, 61.22%; H, 3.42%; N, 19.04%.
Similarly were prepared: -E_: 2-Ethoxy-6-(5-tetrazolyl)xanthone.
Decomp. 272-274 from dimethylformamide.
Found: C, owe; H, 3.94%; N, 18.20%.
C16H12N4O3 requires C, 62.33%; H, 3.92%; N, 18.17%.

~:x.16: 2-Propoxy-6-(5-tetrazolyl)xanthone Decomp. 272-273 from dimethylformamide.
Found: C, 63.39%; H, 4.37%; N, 17.15%.
C17H14N4O3 requires C, 63.35%; H, 4.38%; N, 17.38%.

MC/JAH/21st April.

12~3~J~

Ex.17: 2-Butox~-6-(5-tetrazolyl)xanthone Decomp. 249-25D from dimethylformamide.
Found: C, 64.37%; H, 4.71%; N, 16.54%.
C18H16N4O3 requires C, 64.28%; H, 4.79%; N, 16.66%.

Ex.18: 2-Isopropoxy-6-(5-tetrazolyl)xanthone Decomp. 263-265 from 2-methoxyethanol.
Found: C, 63.27%; H, 4.37%; N, 17.25%.
C17H14N4O3 requires C, 63.35%; Ho 4.35%; N, 17.39%.

Ex.19: 2~Methylthio)-6-(5-tetrazolyl)xanthone Mop. 253-255 from aqueous 2-methoxyethanol.
Found: C, 58.34%; H, 3.23%; N, 17.97%; S, 10.29%.
Clown requires C, 58.06%; H, 3.22%; N, 18.06%; S, 10.32%.

Example 20 2-(3-Hydroxypropoxy) 6-(5-tetrazolyl)xanthone 2-(3-Acetoxypropoxy)-6-cyanoxanthone (3.25 9), sodium aside (~.66 9), ammonium chloride (0.57 9) and dimethylformamide (50 ml) were heated together at 125 for 5 h. The reaction mixture was poured into water, and made alkaline with sodium hydroxide solution. The solution was extracted twice with chloroform to remove unchanged nitrite, and then acidified with hydrochloric acid to precipitate crude 2-(3-acetoxypropoxy)-6-(5-tetrazolyl)xanthone, 2.85 9, mop. 240 (decomposes).
The Aztecs compound (1.5 I was boiled under reflex with sodium hydroxide (3.0 9) in water (30 ml) for 1.5 h., and the solution acidified with hydrochloric acid. Thy precipitated solid was filtered off and recrystallized MC/JAH/21st April.

;~2~3(}~
I

from dimethylformamide to yield 2-(3-hydroxypropoxy)-6-(5-tetrazolyl)xanthone mop. 270 (decomposes).
Found: C, 60.37%; H, 4.27%; N, 16.72%.
C17H14N4O4 requires C, 60.35%; H, 4.17%; N, 16.56%.

Similarly prepared was:
Ex.21: 2-(2-Hydroxyproooxy)-6-(5-tetrazolyl)xanthone Mop. 250 (decomposes).
Found: C, 60.08%; H, 4.21%; N, 16.62%.
C17H14N4O4 requires C, 60.35%; H, 4.17%; N, 16.56%.

Example 22 7-MethoxYxanthene-3-carboxylic acid 7-Methoxyxanthone-3-carboxylic acid (10.0 9) was reduced by the Clemmensen method, using zinc amalgam prepared from zinc powder ~100 g) and mercuric chloride (8.0 g), in acetic acid at ambient temperature. The product, 7 methoxyxanthene-3-carboxylic acid, was obtained by chromatography on silica gel, eluding with 5% methanol in chloroform, and had mop. 259-261.
Found: C, 70.41%; H, 4.78%. KIWI requires C, 70.3û%; H, 4.72%.

Preparation ox sodium salts 7-Methoxyxanthone-3-carboxylic acid sodium salt (En. lay 7-Methoxyxanthone-3-carboxylic acid (32.9 9) was heated with a solution of sodium bicarbonate (10.08 9) in water (1 lithe), the solution filtered and evaporated to dryness. The residual solid was ground to a powder and dried in MCtJAH/21st April.

I

vacua over calcium chloride to give the sodium salt, analyzing for 0.25 mole water of crystallization.
Found: C, 60.61%; H, 3.22%. C15HgNaO5Ø25 H20 requires C, 60.72%;
H, 3.23%.
The following sodium salts were similarly prepared from the fully characterized free carboxylic acids or tetrazoles. The number of moles of water of crystallization may vary for different preparations of the same sodium salt according to the conditions of drying and exposure to atmospheric moisture:
7-Ethoxyxanthone-3-carboxylic acid Sodom salt (Ex.2a) Freeze dried, MindWrite.
Found: C, 59.43%; H, 3.52%. Clown requires C, 59.26%; H, 4.04%.

7-Propoxyxanthone-3-carboxylic acid sodium salt tweaks) Freeze dried, MindWrite.
Found: C, 60.49%; H, 4.12%. C17H13NaO5.H2O requires C, 60.35%; H, 4.47%.

7-lsopropoxyxanthone-3-carboxylic acid sodium salt (Ex.5a) Freeze dried, MindWrite.
Found: C, 59.72%; H, 4.00%; Loss on drying at 120, 4.94%.
C17H13NaO5.H2O requires C7 60.35%; H, 4.47%; HO, 5.33%.

7-~Methylthio)xanthone-3-carboxy to acid sodium salt (Ex.4a) Freeze dried, MindWrite.

MCGEE sty April.

;~2g3~9~
`" 40 Found: C, 55.6}%; H, 3.21%; 5, Dow; Loss on drying at 120%, 4.78%.
C15Hg Noah requires C, 55.20%; H, 3.4D%; 5, 9.82%; HO, 5.52%.

7-Hydroxyxanthone-3-carboxylic acid sodium salt (Ex.6a) Dried at room temperature in vacua; dehydrate.
Found: C, 53.67%; H, 2.79%. C14H7NaO5.2H2O requires C, 53.50%: H, 3.53%.

7-(2-Hydroxyethoxy)xanthone-3-carboxylic acid sodium spa (Exile) Dried at room temperature; sesquihydrate.
Found: C, 54.93%; H, 3.92%. Clown requires C, 55.02%;
H, 4.04%.

- 7-(3-Hydroxypropoxy)xanthone-3-carboxylic acid sodium salt (Ex.8a) Dried at 80 in vacua/ hemihydrate.
Found: C 55.68%; H, 3-64%- C17H13N4NaO4Ø5H2O q 55.29%; H, 3.82%.
2-Methoxy-6-(5-tetrazolYl)xanthone sodium salt (Ex.14a) Dried at 80 in vacua, exposed to air at room temperature. Tetrahydrate.
Found: C, 46.44%; H, 4.34%; N, 14-58%- C15HgN4NaO3.4H2O require C, 46.4û%; H, 4.41%; N, 14.43%.

2-Ethoxy-6-(5-tetrazolyl)xanthnne sodium salt (Ex.15a) Dried at 80 in vacua, exposed to air at room temperature. MindWrite.
F d: C 55 34%; H, 4.00%; N, 16-11%- C16HllN4NaO3.H2O r q C, 55.17%; H, 3.76%; N, 16.08%.

MC/OAH/21st April.

I
Al 2-Propoxy-6-(5-tetrazolyl)xanthone sodium salt (Ex.16a) Dried at room temperature, 2.25 hydrate.
Found: C, 53.15%; H, 4.36%; N, 14.65%. C17H14N4NaO3. OWE
requires I 53.05%; Ho 4.58%; No 14.56%.

2-lsopropoxy-6-(5-tetrazolyl)xanthone sodium salt (Ex.18a) Freeze dried, 3.5 hydrate.
Found: C, 50.13%; H, aye%; N, 13.36%; loss on drying at 120, 14.77%.
C17H13N4NaO3.3.5H2O requires C, 50.12%; H, 4.95%; N, 13.75%; HO, 15.48%.

2-(Methylthio)-6-(5-tetrazolYl)xanthone sodium salt (Ex.lga) Freeze dried, trihydrate.
Found: C, 46.69%; H, 3.74%; N, 14.31%; S, 8.11%; loss on drying at 120, 13.81%. C15HgN4NaO2S.3H2O requires C, 46.63%; H, 3.91%; N, 14.50%; S,

8.3~%; HO, 13.99%.

2-(2-Hydroxypropoxy)-6-(5-tetrazolYl)xanthone sodium salt (Ex.21a) Dried at 80 in vacua, MindWrite.
F undo C 53 96%; H, 4.0Q%; N, 14.58%. C17H13N4NaO4.H2O q C, 53.97%; H, 4.07%; N, 14.81%.

2-(3-Hvdroxypropoxy)-6-(5-tetrazolyl)xanthone sodium salt (Ex.20a) Dried at 80 in vacua, one-third hydrate.
Found: C, 58.68%, H, 3.64%; N, 15.14%. C17H13N4NaO4. OWE
requires C, 55.74%; H, 3.76%; N, 15.29%.

MC/JAH/21st April.

- ~Z2~3~
Example 23 7-t2 Acetoxyethoxy)xanthone-3-carboxylic acid 7-(2-Hydroxyethoxy)xanthone-3-carboxylic acid (4.0 g) was boiled under reflex with acetic android (200 ml) for 3 h. The solution was evaporated to dryness and the residue recrystallized from acetic acid to yield 7-(2-acetoxyethoxy)xanthone-3-carboxylic acid, mop. 248-2490C.

Found: C, 63.08%; H, 4.18%. C18H1407 requires C, 63.16~; H, 4.12%

Example 24 2-t2-Acetoxyethoxy)-6-(5-tetrazoLyL)xanthone PA) 7 ~2-Acetoxyethoxy~xanthone-3-carboxamide . _ 7-(2-Acetoxyethoxy)xanthone-3-carboxylic acid (3.4 9) was boiled under reflex with thinly chloride (50 ml) for 2 h. The resulting solution was evaporated to dryness and the residual acid chloride added to ice-coLd concentrated ammonia solution with stirring. After 2 h the aside was filtered off and dried, yielding 3.3 9, mop. 230-2320C.

(B) 2-(2-Acetoxyethoxy)-6-cyanoxanthone The aside from step (A) (3.3 g) was added to a solution of thinly chloride (7 my in dimethylformamide (5Q ml) at -10~. The mixture was stirred at ice-bath temperature for 3 h, then poured into iced water.
The precipitated nitrite was filtered off, washed with water, and dried to Yield 2.9 g, mop. 194-196C.

:3LZ~S~3~9~

(C) 2-(2-Acetoxyethoxy)-6-(5-tetraZOlYl~xanthone_ The cyanoxanthone from step (B) (2.9 9), sodium aside (0.61 93, ammonium chloride (0.53 9) and dimethylfor~amide(50 ml) were heated together at 125 for 8 h. The reaction mixture was poured into an iced aqueous solution of hydrochloric acid (excess) and the product filtered off and dried. Recrystallization from dimethylfo ~amideyielded the title compound,m.p. 216-218C

Found: C, 58.96%, H, 3.84%, N, 15.01%. C18H14N405 requires C, 59-02%C
H, 3.85%; N, 15.29%.

Example 25 2-(2-Hydroxyethoxy)-6-(5-tetrazolyl)xanthone 2-(2-Acetoxyethoxy)-6-(5-tetrazolyl)xanthone (1.0 9) was boiled under reflex with a solution of sodium hydroxide t2.0 9) in water t20 ml) for 2.5 h. The solution was cooled and poured into excess aqueous hydrochloric acid and the precipitated product filtered off washed with water, and dried. Recrystallization from dimethylformamide gave the title compound, mop. 270C.tdecomposes).

Sodium salt text 25 a ) The free tetrazole (13.45 y) was dissolved by warming with a solution of sodium bicarbonate (3.48 93 in water (150 my The cooled solution was filtered, extracted once with chloroform, and evaporated to dryness. The residue was dried at room temperature in vacua over phosphorus pent oxide to yield 2-(2-hydroxyethoxy)--6-(5-=tetrazoly~)-xanthone sodium salt dehydrate. Found: C, 50~46%; H, 3.79%; N, 14.52%~
C16H15N4NaO6 requires C, 50.26~; H, 3.95%; N, byway%.

1~2Z93 Example 26 2-C2-(2-Hydroxyethoxy)ethoxy]xanthone-6 carboxyl;c acid .. . .

7-Hydroxyxanthone-3-carboxylic acid (75.0 9), ethylene carbonate (3Z5 9) and tetrabutylammonium iodide (1.75 9) were heated together with stirring for 5 h. The cooled reaction mixture was diluted with ethanol and the solid residue filtered off and boiled with sodium and water (1.0 L) hydroxide (175 9) in ethanol (1.0 for 4 h. The mixture was filtered, and the filtrate diluted with water (2.0 l) and acidified with dilute hydrochloric acid. The solid product was filtered off, washed with water and recrystallized from 2 methoxyethanol, mop. 188~C.

Analysis Cafe% 62.78 4.68 Found% 62~52 4.73 En _ 26 a The above product acid (1 9) was boiled with sodium bicarbonate (0.244 9) in water (200 ml); the cooled solution was filtered and freeze dried to yield the sodium salt as a pale yellow solid, mop. greater than 350C.

Example 27 2 (2-~utyryloxyethoxy)xanthone-6-carboxylic acid 2-(2-~ydroxyethoxy)xanthone-6-carboxylic acid t10 9) was reflexed with us " ~Z~93~
butyric android (250 my) for 2 h. The resultant solution was evaporated and the residue triturated with ether. Recrystallization from dimethylformaMide/water gave the title carboxylic acid, mop.
237-241C.

Analysis C H
Cafe% 64.~6 4.89 Found% 65.05 4.87 En. aye The corresponding sodium salt was obtained as a pale yellow solid, mop. greater than 350Cn Example 28 2-C2-(2-Acetoxyethoxy)ethoxy]xanthone-6-carboxylicc acid 2-[2-t2-Hydroxyethoxy)ethoxy]xanthone-6-carboxylicc acid ~10 9) was reflexed in acetic android (150 ml) for 2 h. The resultant solution was evaporated and the residue triturated with ether. Recrystallization from methanol gave the product as yellow crystals, mop. 199-200C.

Analysis C H
Cafe% 62.17 4.69 Found% 62.û8 4.63 ~93 En. 28 a The corresponding sodium salt was obtained as a pale yellow solid, mop. greater than 350C.

Example 29 2-t2-Butyryloxyethoxy)-6-(S-tetrazolyl)xanthone (A) 2-(2-Butyryloxyethoxy)xanthone-6-carboxamide 2-(2-Butyryloxyethoxy)xanthone-6-carboxylic acid t8.0 g) was reflexed with thinly chloride (100 ml) for 1 h. The resultant solution was evaporated to dryness and the residual acid chloride added portions to ice-cold 0.880 ammonia solution with stirring. After 2 h the solid was-filtered-off and washed with water Recrystallization from 2-methoxyethanol gave the indicated product, mop. 205-2070C.

Analysis C H N
Cafe% 65.û3 5.19 3.79 Found% 65.35 5.18 3.67 (B) 2-(2-Butyryloxyethoxy)-6-cyanoxanthone Thinly chloride (10 ml) was added drops to a stirred suspension of the carboxam;de from step (A) (5.22 g) in dimethylformamide (100 ml) at -10C. The mixture was kept at ice bath temperature for 1 h, then poured into iced-water. The solid precipitate was filtered off and recrystallized from glacial acetic acid yielding the title cyanoxanthone, mop. 145-147C.

I
Z~3 (C) Z-(2-Butyryloxyethoxy)~6-(5~tetrazolyl)xanthone The cyanoxanthone from step (B) (4.17 go, sodium aside (0.82 9) ammonium chloride Tao 9) and dimethylformamide (100 ml) were stirred together at 120C for 8 h. The cooled mixture was poured into iced 2 M hydrochloric acid, warmed to OKAY for 10 minutes, cooled and filtered. The resultant solid was rerrystallised from water yielding dimethylformamide~the title xanthone, mop. 207-2090C.

Analysis C H N
Cowlick 60.90 4.61 14.22 Found% 60.93 4.55 14.12 En. 29 a The corresponding sodium salt was obtained as a pale yellow solid, mop. 275-2800C.(decomp.).

Example 30 2-(Ethylthio)xanthone-6-carboxylic acid -(~) Diethyl-2-(4-ethylthiophenoxy)terephthalate Sodium metal (3.4 9) was added over 20 minutes to a stirred solution of 2-(4- ethylthiophenoxy)terephthalic acid (10 9) in hexamethyl-phosphoramide (100 ml) at 100C under dry nitrogen. After 2 h the mixture was cooled and treated with ethyl iodide (20 ml) with ice bath cooling to maintain the temperature below 450C. After a further 30 :~2~3~L

minutes the mixture was poured into water and ether extracted. The organic extracts were washed with brine, dried over magnesium sulfite and evaporated. Chromatography of the residual oil over silica,eLuting with chloroform/60-80 petrol ~2:3, v/v) and C8 Zorba reverse phase HPLC eluding with methanol/water (7:3, v/v) gave the product as an oil.

(B) 2-(4-Ethylth;ophenoxy)terephthalic acid The divester from step (A) (1.9 9) was boiled under reflex with a solution of sodium hydroxide (5.6 9) in water (70 ml) and ethanol (30 ml). After 2 h the mixture was cooled and diluted with water (100 ml). Acidification with concentrated hydrochloric acid yielded the product acid which was filtered off and dried, mop. 282-284C.

(C) 2-~Ethylthio)xanthone-6-carboxylic acid The terephthalic acid from step (B) (1.3 9) was boiled under reflex with phosphorus oxychloride (50 ml) for 8 h. The cooled reaction mixture was cautiously decomposed by adding to water, controlling the temperature below 80C by ice addition. The precipitated solid was filtered off, washed with water and recrystallized from d;methylformamide/
water giving the title carboxylic acid, mop. 234-2360C.

Analysis C H
Cowlick 63.99 4~03 Found% 63.98 4.10 *Trade Mark aye En. 30 a The corresponding sodium salt was obtained as a yellow powder, mop.
greater than 35ODC~

Example 31 2-Ethylthio-6-_5-tetrazolyl)xanthone (A) 2-(Ethylthio)xanthone-6-carboxamide 2-(Ethylthio)xanthone-6-carboxylic acid (0.65 9) was boiled under reflex with thinly chloride (50 ml) for 1 h. The resultant solution was evaporated to dryness and the residual acid chloride added portions to ice-cold 0.8~0 ammonia solution with stirring. After 2 h the solid was filtered off and washed with water yielding the product carboxamide (0.62 9), mop. SKYE.

(B) 2~thylthio-6-cyanoxanthone Thinly chloride (1.5 ml) was added drops to a stirred solution of the carboxamide from step (A) (0.55 9) in dimethyLformamide (20 ml) at 5C. The mixture was kept at ice-bath temperature for 1 h, then poured into iced water. The solid precipitate was filtered fry dried and chromatographed on silica eluding with ethylene chloride/60-80 petrol (1:1, v/v) giving the title cyanoxanthone (0.44 9), mop.
159-161C.

(C) 2-Ethylthio-6-(5-tetrazolyl)xanthone The cyanoxanthone from step (B) (0.42 9), sodium aside (0.102 9), .

293~

ammonium chloride (0~088 9) and dimethyLformamide t25 ml) were stirred together at 120C for 10 h. The cooled mixture was poured into iced 2 M hydrochloric acid, warmed to 800C for 10 minutes, cooled and filtered The resultant solid was extracted into 5%
sodium bicarbonate solution and washed with ether. Acidification of the base extracts gave the title compound which was filtered off and dried, mop. 261-262C.

Analysis C H N
Cowlick 59.24 3.73 17.28 Found% 59.25 3.76 17.32 En. 31 a The corresponding sodium salt was obtained as a yellow powder, mop.
335-3360C.

example 32 2-(Methylthio)xanthene-6-carboxylic acid (A) 2-Methylthio-6-hydroxymethyl~anthene orate tetrahydrofuran complex (30 ml, 1 M solution on tetrahydrofuran) was added under dry nitrogen to an ice cold stirred solution o-f 2-(methylth;o)xanthone-6-carboxylic acid (3 9) in dry tetrahydrofuran (100 ma After 1 h the mixture was allowed to attain room temperature and stirred for 12 h. The excess borne was decomposed by 93~
.
addition of ice and the resultant solution extracted with ethyl acetate.
The organic extracts were washed with brine, dried over magnesium sulfite and evaporated yielding the title compound ~2.39 g) as a white solid, mop. 151-153C.

(B) 2-(Methylthio)xanthene-6-carboxaldehyde _ Under dry nitrogen, dimethylsulphox;de (5 ml) was added drops to a stirred solution of oxalyl chloride (0.89 ml) in ethylene chloride (S ml) at -600C. After 2 minutes a solution of the xanthene from step (A) (2.3 g) in dimethylsulphoxide (35 ml) was introduced drops over 5 minutes whilst maintaining the temperature below -500C
with cooling. After 15 minutes triethylamine (6.20 ml) was added, the mixture allowed to warm to room temperature and then poured into water.
The mixture was ethyl acetate extracted, the organic layers were combined, washed with brine, dried over magnesium sulfite and evaporated yielding the title carboxaldehyde ~1~97 9), mop. 122-123C.

(C) 2-Methylthio-6-cyanoxanthene A mixture of the carboxaldehyde from step (~) (1.75 g), hydroxylamine hydrochloride (~.56 g), sodium format (1 9) and formic acid (15 ml) was reflexed for 1 h. The resultant solution was diluted with water and ether extracted, the extracts were washed with brine, dried over magnesium sulfite and evaporated. The residual solid was chromatographed over silica eluding with chloroform/methanol (98:2, v/v) yielding the title cyanoxanthene (1.58 9), mop. 142-144C.

~2~3~
so (D) 2-(Methylthio)xanthene-6-carboxylic acid The cyanoxanthene from step (C) (0.3 9) was boiled under reflex with a solution of sodium hydroxide (3 9) in water (10 my) and ethanol (10 my) for 6 h. The resultant solution was diluted with water, ether extracted, and acidified with concentrated hydrochloric acid. The precipitated carboxylic acid was filtered off, washed with water and dried, mop. 266-2670C.

Analysis C H
Cafe% 66.20 4.45 Found% 66.24 4.82 En. 32 a The corresponding sodium salt was obtained as a white powder, mop.
greater than 3OODC.

Example 33 2-Hydroxy-6-(5-tetrazolyl)xanthone (A) 3-t5-Tetra~olyl)xanthone 3-(5-Tetra2Olyl)thioxanthone-10,10-dioxide sodium salt US patent specification 1,447,031; 45.0 9) was stirred and boiled under reflex with 2-normal sodium hydroxide solution for I hours The solution was acidified by pouring into excess hydrochloric acid solution and ~2SZ3~3~

the precipitated product filtered of and recrystallized from dimethylformamide to give the title compound (14.95 9), met 2960C.
(decomposes).

Calculated: C, 63.64%, H, 3.05%, N, 21.20%

Found : I, 63.77%, H, 3.Q5%, N, 21.15%

to) 2-Nitro~6-(5-tetrazolyl)xanthorle 3-(5-TetrazoLyl)xanthone (1.0 g) was dissolved in concentrated sulfuric acid (10.0 ml) and the resulting solution cooled to below 15C. Potassium nitrate (0.50 9) was added in small portions over 10 min. with cooling to maintain the temperature between 10 and Canada the reaction mixture was then stirred at 200C.for 1 hr. The reaction mixture was poured on to ice and the precipitated product filtered off, washed with water and recrystallized from d;methylformamide. The crystallized product was washed with methanol and dried at 156C/2Q mm Hug to yield 0.78 go met. cay Cathy decomposition.

found : C, 54.11%; H, 2.25%i No 22.60X C14H7N504 requires : C, 54.38%; H, 2.28/'; N, 22.65%.

(C) 2-Am;no-6-~5-tetrazolyl)xanthone The n;troxanthone from step (~) (1.55 9) was dissolved in a solution of sodium bicarbonate (0.42 9) in water ~150 ml) with warming. To the solution was added 10% palladium on carbon catalyst and the solution hydrogenated at room temperature and atmospheric pressure for 4 ho, during which time hydrogen uptake was miswords 440 ml. The solution ~2Z93~
, "`, SLY

was filtered and the filtrate acidified with twice-normal hydrochloric acid solution. The amino-compound was filtered from the warmed mixture, washed well with water and dried to yield 0.98 9, met. 296 -Cathy decomposition Found : C, 56-38%; H, 3.71%, N, 23.58% Clown requires : C, 56.57%; H, 3.73%, N, 23.56%.

(D) 2-Hydroxy-6-~5-tetrazolyl)xanthone The aminoxanthone from step (C) (14~4 9) was dissolved in concentrated sulfuric acid (250 ml) and to the stirred solution at Casey added in portions sodium nitrite (3.6 9). The solution was then stirred at 150C.for 1 ho, poured on to ice (2 kg) and water (2.5 l).
The mixture was slowly brought to the boil and boiled under rollicks for 1 hr. The resulting yellow product was filtered off, washed well with water and Druid A sample was purified by chromatography on silica gel~eluting with chloroform-methanol 3:1 v/v, met.

Found : C, %; H, X; N, 14 No 3 requires : C, 60.00%; H, 2.87%; N, 20.00%~

Exam 34 2 (2-Hydroxyethylthio)-6-(5-tetrazolyl)xanthone 2-Amino-6-(S~tetrazolyl)xanthone (4.60 g) was dissolved by stirring in concentrated sulfuric acid (80 ml) at Cole in portions, over so 10 mint was added sodium nitrite (1.15 9) with cooling to maintain the temperature at 153C. The mixture was stirred at 153C.for 1 ho, then poured on to ice The solid diazonium sulfite was filtered off and washed with a little cold water.

The solid salt was added to a hot (503C) solution of 2-mercaptoethanol to ml) in water (50 ml) in portions. Vigorous effervescence took place.
The mixture was kept at 503C.for 30 mint then the solid product was filtered off and washed with water. Flash chromatography of the dried crude product on silica gel, eluding with chloroform-acetic acid 4:1 TV
followed by recrystallization once from aqueous dimethyLformamide and twice from 2-methoxyethanol, yielded the title compound, met. Cathy decomposition), structure supported by nor spectroscopy.

Found : I 56-09%;-H, 3.h9%, N,--16.28% -C16H12N405S-requires : C, 56~46%; H, 3.55%,~ N, 16,46%.

/
/

AL
3~9t Example 35 Activity in whole human blood in vitro Human blood was collected from volunteer donors into CUD
anticoagulant medium in the ratio 100 ml blood: 15 ml medium; 1 ml allocates were dispensed into 2 ml polycarbonate vials and then kept for three hours at 4C to allow the cells to settle out from the plasma. The samples were then held at room temperature while the test compounds, one per vial, were added according to the following procedure to provide a 6 my concentration in whole blood volume:

A small volume of plasma was removed from each vial: sodium salts TV
were dissolved therein directly while acids TV were added to warm aqueous sodium bicarbonate (3ûû my, 2 drops) which was then mixed with the plasma; in either case the compound-laden plasma was then returned to the original vial, the vial capped and the contents mixed thoroughly.

For each experimental series three control vials were also prepared containing respectively:
a) blood alone b) blood + hydrochloric acid Old 150 microlitre) c) blood + aqueous sodium hydroxide (Alma, 150 microlitre).

After a total of two hours at room temperature all samples were left at 37C for 16 hours and the pi of each then measured at that temperature. The vials were then stored on ice and the oxygen-dissociation curve determined for each sample using a whole-blood spectrophotometer (Hem-O-Scan, Trade Name). Finally, after rewarming to 37C, the pi of each sample was remeasured.

MlCjJAH/21st April.

~2~93~
., so The right-displacement of the Pi point (the oxygen tension at which the hemoglobin is 50% saturated with oxygen) for the oxygen-dissociation curve was ascertained for each sample relative to the calculated Pus value for the appropriate sample phi The results are given below.

* CUD anticoagulant is an aqueous solution containing the following per 100 ml:

Sodium citrate 2~63 9 An hydrous dextrose 2.32 9 Citric acid MindWrite 0.327 9 Sodium acid phosphate 0.251 9 Compounder hut -displacement tam Hug Eye 13.0-Ex.2 16.2 Ex.3 13.0 Ex.4a 15.6 Excuse 9 7 Ex.6a 5.3 Ex.8a 25.8 Ex.9 6.9 Ex.11a 25.0 Ex.12 23.1 Ex.13 19.9 Ex.14a 18.8 Ex.15a 27.4 so I !93(:1gt Ex~16a 23.2 Ex.17 14~6 Ex.18a 12.6 Ex.19a 9,5 Ex~20a 23.5 Ex~21a 28.7 Ex.22 17.3 Ex.23 19.0 Ex.24 20.0 Ex.25a 32.6 Ex~26a 25.6 Ex.27a 25~5 Ex.28a 26.1 Ex.29a 22.2 Ex.30a 20.0 Ex.31a - 16.6 Ex.32a 16.2 Ex.34 17.7 to)* 7.6 tub)* -owe**
to)* 3.5 * Japanese patent Cook no. 16821/82:
to): 3-t1H-tetrazol -5-yl)thioxanthone-10,10-dioxide (B): 7-methoxy-2-(1H-tetrazol-5-yl)xanthone to): 2-(1H-tetrazol-5-yl)xanthone ** denotes a left-displacement ~2Z~3~

Example 36 Cardiovascular effects in the anesthetized rat Male Wisteria rats (240-420 9) were used, anesthesia being induced with halothane/oxygen and maintained by CC-chloralose and sodium pentobarbitone ivy. Test compounds (Ens. aye and aye) were given ivy. as a solution in 5% dextrose and at a dose volume of 1.0m~/kg given over 5 sec. and flushed in with 5% dextrose solution Tao ml);
doses were given in ascending order at 10-30 mix intervals over the range 0.001 - 30 mg/kg.
Both compounds induced a dose-related hypotension in the dose range 3-3U mgfkg.

No significant waveform abnormalities were apparent in the electrocardiogram following either compound.

-Example 37 Toxicity Data The compounds indicated were administered ivy. to female CD1 mice Charles River US Ltd.).

For En. aye the LDsO was found to lie between 140 mg/kg and 200 mg/kg (calculated as the free acid).

For En. aye the LDso was found to be greater than 600 mg/kg.

Jo ISLES
Example 38 Pharmaceutical Formulations (A) CAPSULE
Compound (Acadia my Starch 1500 250 my Magnesium Stewart my 883 my Mix the ingredients using a suitable mixer and fill into capsules on a capsule filling machine.

(B) TABLET
Compound (Acadia my Lactose 200 my Polyvinylpyrrolidone 50 my Starch 100 my Magnesium Stewart my 985 my Dissolve the polyvinylpyrrolidone in a suitable volume of water.
yucca the compound, lactose and starch and add the polyvinylpyrrolidone solution. Add a further quantity of water if required. Pass through a suitable screen and dry. Add the magnesium Stewart, mix and compress on a tabulating machine.

by (C) SUPPOSITORY
Compound sodium salt, equivalent to acid 1.25 9 Hard fat BY to 3 ml Melt part of the hard fat at 500C maximum. Add the compound to the molten base and disperse. Add the remaining hard fat to the suspension. When a smooth homogeneous suspension has been obtained pour the suspension into 3 ml mounds.

to) INJECTION
Compound sodium salt, equivalent to acid 1.25 9 Minutely BY 125.0 my Water for injections BP/Ph/Gm to 2.5 ml .
Dissolve the compound and the minutely in 2/3 the final quantity of water for injections. Make to volume with more water for injections Sterilize the solution by passage through a sterilizing grade filter Fill 2.5 ml portions into suitable vials under aseptic conditions and freeze dry When drying is complete seal the vials under an atmosphere of oxygen free nitrogen and cap with aluminum collars go (E) INJECTION
Compound acid) 2~50 9 Bouncily alcohol 90.0 my TRIP solution (0.05 M) 5 ml Hydrochloric acid (0.1 N) 3 my Water for injections BP/Ph/Gm to 10 ml Dissolve the compound in the TRIP and hydrochloric acid.
Add and dissolve the bouncily alcohol and make to volume with water for injections. Strolls the solution by filtration through a suitable sterilizing grade filter. Fill unto 10 ml vials under aseptic conditions and seal with rubber closures.

In the foregoing, acid) indicates that the compound of formula to)) is present as the free carboxyl or 5-tetrazolyl acid, as appropriate.

Example 39 Blood Storage A sterile, sealed bag (Phenol, Triennial Laboratories Lid Thetford, Norfolk, England) suitable for collection of SUE ml blood and containing 63 ml of CUD anticoagulant solution, was taken . Under sterile conditions the anticoagulant was removed, admixed with an effective non-toxic amount (vise swooper) of a compound of formula (I) and returned to the bag and the bag then resealed and stored at room temperature.

Blood from a volunteer human donor was subsequently collected into the bag by conventional procedures and the lull bag then stored at 4~-6DC.

Claims (36)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A sterile, sealed vessel containing an anti-coagulant and a non-toxic amount of a tricyclic com-pound of formula (I):

(I) wherein X1 is a carboxyl or 5-tetrazolyl group, X2 is carbonyl or methylene, X3 is hydroxyl or a group -X4(CnH2n)X5 where X4 is oxygen or sulphur, X5 is hydrogen or a group -OX6 where X6 is hydrogen, alkanoyl of 1 to 4 carbon atoms or a group -(CmH2m)X7 where X7 is hydrogen or a group -OX8 where X8 is hydrogen or alkanoyl of 1 to 4 carbon atoms and m and n are each, independently, an integer from 1 to 4, provided that when X5 is a group -OX6 then n is always greater than 1 and X4 and X5 are attached to different carbon atoms and that when X7 is a group -OX8 then m is always greater than 1 and no single carbon atom in the radical -(CmH2m)- is attached to two oxygen atoms, or a pharmacologically acceptable salt thereof.

2. A sterile, sealed vessel according to claim 1, wherein X1 is a carboxyl or 5-tetrazolyl group, X2 is carbonyl or methylene, X3 is hydroxyl or a group -X4(CnH2n)X5 where X4 is oxygen or sulphur, X5 is hydrogen or a group -OX6 where x6 is hydrogen or alkanoyl of 1 to 4 carbon atoms, and n is an integer from 1 to 4, provided that when X5 is a group OX6 then n is always greater than 1 and X4 and X5 are attached to different carbon atoms.

3. A sterile, sealed vessel according to claim 1, wherein X1 is 5-tetrazolyl, X2 is carbonyl, and X3 is 2-hydroxyethoxy.

4. A sterile, sealed vessel according to claim 1, wherein X1 is 5-tetrazolyl, X2 is carbonyl, and X3 is ethoxy.

5. A sterile, sealed vessel according to claim 1, wherein said compound (I) is 2-ethoxy-6-(5-tetrazolyl) xanthone.

6. A sterile, sealed vessel according to claim 1, wherein said tricyclic compound comprises a pharma-cologically acceptable salt of 2-ethoxy-6-(5-tetrazolyl)-xanthone.

7. A sterile, sealed vessel according to claim 1, wherein said compound (I) is 2-(2-hydroxyethoxy)-6-(5-tetrazolyl)xanthone.

8. A sterile, sealed vessel according to claim 1, wherein said tricyclic compound comprises a pharmacologically acceptable salt of 2-(2-hydroxy-ethoxy)-6-(5-tetrazolyl)xanthone.

9. A sterile, sealed vessel according to claim 1, 2 or 3, wherein the tricyclic compound is in the form of a sodium salt.

10. A sterile, sealed vessel according to claim 4, wherein the tricyclic compound is in the form of a sodium salt.

11. A sterile, sealed vessel containing human erythrocytes, an effective amount of an anticoagulant and a non-toxic amount of a tricyclic compound of formula (I):

(I) wherein X1 is a carboxyl or 5-tetrazolyl group, X2 is carbonyl or methylene, X3 is hydroxyl or a group -X4(CnH2n)X5 where X4 is oxygen or sulphur, X5 is hydrogen or a group -OX6 where X6 is hydrogen, alkanoyl of 1 to 4 carbon atoms or a group -(CmH2m)X7 where X7 is hydrogen or a group -OX8 where X8 is hydrogen or alkanoyl of 1 to 4 carbon atoms and m and n are each, independently, an integer from 1 to 4, provided that when X5 is a group -OX6 then n is always greater than 1 and X4 and X5 are attached to different carbon atoms and that when X7 is a group -OX8 then m is always greater than 1 and no single carbon atom in the radical -(CmH2m)- is attached to two oxygen atoms, or a pharmacologically acceptable salt thereof.

12. A sterile, sealed vessel according to claim 11, wherein X1 is a carboxyl or 5-tetrazolyl group, X2 is carbonyl or methylene, X3 is hydroxyl or a group -X4(CnH2n)X5 where X4 is oxygen or sulphur, X5 is hydrogen or a group -OX6 wherein X6 is hydrogen or alkanoyl of 1 to 4 carbon atoms, and n is an integer from 1 to 4, provided that when X5 is a group OX6 then n is always greater than 1 and X4 and X5 are attached to different carbon atoms.

13. A sterile, sealed vessel according to claim 11, wherein X1 is 5-tetrazolyl, X2 is carbonyl, and X3 is 2-hydroxyethoxy.

14. A sterile, sealed vessel according to claim 11, wherein X1 is 5-tetrazolyl, X2 is carbonyl, and X3 is ethoxy.

15. A sterile, sealed vessel according to claim 11, wherein said compound (I) is 2-ethoxy-6-(5-tetrazolyl)xanthone.

16. A sterile, sealed vessel according to claim 11, wherein said tricyclic compound comprises a pharma-cologically acceptable salt of 2-ethoxy-6-(5-tetrazolyl)-xanthone.

17. A sterile, sealed vessel according to claim 11, wherein said compound (I) is 2-(2-hydroxyethoxy)-6-(5-tetrazolyl)xanthone.

18. A sterile, sealed vessel according to claim 11, wherein said tricyclic compound comprises a pharmacologically acceptable salt of 2-(2-hydroxy-ethoxy)-6-(5-tetrazolyl)xanthone.

l9. A sterile, sealed vessel according to claim 11, 12 or 13, wherein the tricyclic compound is in the form of a sodium salt.

20. A sterile, sealed vessel according to claim 14, wherein the tricyclic compound is in the form of a sodium salt.

21. A method for maintaining the oxygen-delivery capacity of stored human erythrocytes comprising admixing the cells, prior to their transfusion into a recipient, with a non-toxic, maintenance-effective amount of a tricyclic compound of formula (I):

(I) wherein X1 is a carboxyl or 5-tetrazolyl group, X2 is carbonyl or methylene, X3 is hydroxyl or a group -X4(CnH2n)X5 where X4 is oxygen or sulphur, X5 is hydrogen or a group -OX6 where X6 is hydrogen, alkanoyl of 1 to 4 carbon atoms or a group -(CmH2m)X7 where X7 is hydrogen or a group -OX8 where X8 is hydrogen or alkanoyl of 1 to 4 carbon atoms and m and n are each, independently, an integer from 1 to 4, provided that when X5 is a group -OX6 then n is always greater than 1 and X4 and X5 are attached to different carbon atoms and that when X7 is a group -OX8 then m is always greater than 1 and no single carbon atom in the radical -(CmH2m)- is attached to two oxygen atoms, or a pharmacologically acceptable salt thereof.

22. A method according to claim 21, wherein X1 is a carboxyl or 5-tetrazolyl group; X2 is carbonyl or methylene, X3 is hydroxyl or a group -X4(CnH2n)X5 wherein X4 is oxygen or sulphur, X5 is hydrogen or a group -OX6 where X6 is hydrogen or alkanoyl of 1 to 4 carbon atoms; and n is an integer from 1 to 4, provided that when X5 is a group -OX6 then n is always greater than 1 and X4 and X5 are attached to differellt carbon atoms.

23. A method according to claim 21, wherein X1 is 5-tetrazolyl, X2 is carbonyl, and X3 is 2-hydroxyethoxy.

24. A method according to claim 21, wherein X1 is 5-tetrazolyl, X2 is carbonyl, and X3 is ethoxy.

25. A method according to claim 21, wherein the tricyclic compound is 2-(2-hydroxyethoxy)-6-(5-tetrazolyl)xanthone or a pharmacologically accept-able salt thereof.

26. A method according to claim 21, wherein the tricyclic compound is 2-ethoxy 6-(5-tetrazolyl)-xanthone or a pharmacologically acceptable salt thereof.

27. A method according to claim 21, 22 or 23 wherein said tricyclic compound is in the form of a sodium salt.

28. A method according to claim 24, wherein said tricyclic compound is in the form of a sodium salt.

29. A method for prolonging the useful storage life of stored human erythrocytes comprising admixing the cells, prior to their transfusion into a recipient, with a non-toxic, prolongation-effective amount of a tricyclic compound of formula (I), (I) wherein X1 is a carboxyl or 5-tetrazolyl group, X2 is carbonyl or methylene, X3 is hydroxyl or a group -X4(CnH2n)X5 where X4 is oxygen or sulphur, X5 is hydrogen or a group -OX6 where X6 is hydrogen, alkanoyl of 1 to 4 carbon atoms or a group -(CmH2m)X7 where X7 is hydrogen or a group -OX8 where X8 is hydrogen or alkanoyl of 1 to 4 carbon atoms and m and n are each, independently, an integer from 1 to 4, provided that when X5 is a group -OX6 then n is always greater than 1 and X4 and X5 are attached to different carbon atoms and that when X7 is a group -OX8 then m is always greater than 1 and no single carbon atom in the radical -(CmH2m)- is attached to two oxygen atoms, or a pharmacologically acceptable salt thereof.

30. A method according to claim 29, wherein X1 is a carboxyl or 5-tetrazolyl group; X2 is carbonyl or methylene, X3 is hydroxyl or a group -X4(CnH2n)X5 wherein X4 is oxygen or sulphur, X5 is hydrogen or a group - OX6 where X6 is hydrogen or alkanoyl of 1 to 4 carbon atoms; and n is an integer from 1 to 4, provided that when X5 is a group -OX6 then n is always greater than 1 and X4 and X5 are attached to different carbon atoms.

31. A method according to claim 29, wherein X1 is 5-tetrazolyl, X2 is carbonyl, and X3 is 2-hydroxyethoxy.

32. A method according to claim 29, wherein X1 is 5-tetrazolyl, X2 is carbonyl, and X3 is ethoxy.

33. A method according to claim 29, wherein the tricyclic compound is 2-(2-hydroxyethoxy)-6-(5-tetrazolyl)xanthone or a pharmacologically accept-able salt thereof.

34. A method according to claim 29, wherein the tricyclic compound is 2-ethoxy-6-(5-tetrazolyl)-xanthone or a pharmacologically acceptable salt thereof.

35, A method according to claim 29, 30 or 31, wherein said tricyclic compound is in the form of a sodium salt.

36. A method according to claim 32, wherein said tricyclic compound is in the form of a sodium salt.