WO1995008539A1 - Improved methods for preparing bis-imide compounds - Google Patents

Abstract

This invention relates to methods for preparing bis-imide compounds, in particular, bis-naphthalimides which are useful as cancer chemotherapeutic agents. The methods comprise the reaction of one or more anhydrides and a polyamine under heating conditions effective to reduce the formation of side products. The heating step can be conducted in a continuous flow system.

Description

TITLE

Improved Methods for Preparing Bis-imide Compounds

FTELD OF THE INVEN TON

This invention relates to methods for preparing bis-imide compounds, in particular, bis-napthalimides which are useful as cancer chemotherapeutic agents .

BACKGROUND OF THE INVENTION

Bis-naphthalimides which are useful for treating cancer and methods for their preparation have been disclosed in U.S. Patent No. 5,206,249. These compounds, which include 2,2 '-[1,2-ethanediylbis [imino(l-methyl-2, 1- ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline-1, 3 (2H)- dione] and 2,2 '- [1,2-ethanediylbis [imino (2-methyl-2, 1- ethanediyl) ] ]-bis [5-nitro-lH-benz [de]isoquinoline-1,3 (2H)- dione], were prepared by condensation of 3-nitro-l,8- naphthalic anhydride with polyamines in a polar solvent at ambient or less than ambient temperature followed by refluxing. The reaction, which was conducted in standard' glassware using conventional organic synthesis techniques and conditions, produced a mixture of products. Since the desired product resulting from this reaction was present in an impure mixture with undesired impurities, it was necessary to isolate and purify the desired product by column chromatography before the desired product could be converted to a desired salt form and recrystallized. Consequently, a need exists for efficient and cost-effective methods to produce anti-cancer bis-naphthalimides in good yields and with high purity. In particular, there is a need for improved synthetic methods which would result in reduced amounts of undesired reaction side products and impurities thereby obviating the need for a column chromatography purification step to obtain the desired bis-imide products .

SUMMARY OF THE TNVENTTON

The present invention provides a method for preparing symmetrical bis-imide compounds of Formula I comprising the steps of: (a) reacting two equivalents of an anhydride of Formula II with one equivalent of a polyamine of Formula III in a suitable solvent to form an intermediate bis- acid/amide of Formula IVa-IVd and (b) heating the reaction product of step (a) under conditions effective to cyclize and dehydrate the intermediate bis-acid/amide of Formula IVa-IVd; wherein step (b) yields the symmetrical bis-imide of Formula I in purity of greater than 80%.

Another aspect of the present invention is a method for preparing unsymmetrical bis-imide compounds of Formula V comprising the steps of: (a) reacting one equivalent of an anhydride of Formulas Ila or VII with one equivalent of a mono-imide of Formula VI in a suitable solvent to form a imide-acid/amide compound of Formula Vllla-VIIId; and (b) heating the reaction product of step (a) under conditions effective to cyclize and dehydrate the imide-acid/amide of Formula Vllla-VIIId; wherein step (b) yields the unsymmetrical bis-imide of Formula V in purity of greater than 80%.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a method for preparing symmetrical bis-imide compounds of Formula I comprising the steps of: (a) reacting two equivalents of an anhydride of Formula II with one equivalent of a polyamine of Formula III in a suitable solvent; and (b) heating the reaction under conditions effective to yield the symmetrical bis-imide of Formula I in purity of greater than 80% .

The present invention also provides a method for preparing symmetrical bis-imide compounds of Formula I comprising the steps of: (a) reacting two equivalents of an anhydride of Formula II with one equivalent of a polyamine of Formula III in a suitable solvent to form an intermediate bis-acid/amide of Formula IVa, IVb, IVc, or IVd (IVa-d or IVa-IVd) ; and (b) heating the reaction product of step (a) under conditions effective to cyclize and dehydrate the intermediate bis-acid/amide of Formula IVa-IVd; wherein step (b) yields the symmetrical bis-imide of Formula I in purity of greater than 80%.

Another aspect of the present invention is a method for preparing unsymmetrical bis-imide compounds of Formula V comprising the steps of: (a) reacting one equivalent of an anhydride of Formula Ila or VII with one equivalent of a mono-imide of Formula VI in a suitable solvent; and (b) heating the reaction under conditions effective to yield the unsymmetrical bis-imide of Formula V in purity of greater than 80%.

Another aspect of the present invention is a method for preparing unsymmetrical bis-imide compounds of Formula V comprising the steps of: (a) reacting one equivalent of an anhydride of Formula Ila or VII with one equivalent of a mono-imide of Formula VI in a suitable solvent to form a imide-acid/amide compound of Formula Villa, Vlllb, VIIIc, or VHId (Vllla-d or Vllla-VIIId) ; and (b heating the reaction product of step (a) under conditions effective to cyclize and dehydrate the imide-acid/amide of Formula Vllla-VIIId; wherein step (b) yields the unsymmetrical bis-imide of Formula V in purity of greater than 80% .

Steps (a) and (b) of the presently claimed method can be carried out sequentially or essentially simultaneously. Thus, step (a) may be carried out at room temperature to form the intermediate of Formula IVa-d, or Vllla-d, followed by the heating step (b) . Alternatively, the reacting step (a) can be carried out essentially simultaneously with the heating step (b) . Thus, the reactants (the compounds of Formula II and III; or the compounds of Formula Ila or VII and VI) may be mixed together and heated essentially simultaneously.

The methods of the present invention are, therefore, useful for preparing symmetrical or unsymmetrical bis-imide compounds of Formula I, V, or IX which are useful in the treatment of cancer in mammals, particularly in the treatment of solid tumor carcinomas.

The methods of the present invention are advantageous in that the bis-imide compounds of Formula I, V, or IX can be prepared in high purity (greater than 80%, preferably greater than about 95%, and more preferably purity of greater than about 98%) and in high yields (>40%) . When the present method of synthesis is carried out to obtain the desired bis-imide in having a purity of greater than about 98%, the need for subsequent purification by chromatographic methods may be obviated. Moreover, the free base form of the bis-imide products of the present methods can be directly converted to a desired pharmaceutically acceptable salt form.

The reactions of the presently claimed methods are carried out in a suitable solvent, said suitable solvent being any solvent which is substantially nonreactive with the starting materials (reactants) , intermediates, and products at the temperatures at which the reactions are carried out, i.e., temperatures ranging from ambient to the solvent's boiling temperature. Suitable solvents include organic solvents, which include but are not limited to polar organic solvents. Suitable solvents useful in the present invention include but are not limited to ethanol, methanol, isopropanol, toluene, pyridine, dimethylsulfoxide (DMSO) , N,N-dimethylformamide, N,N-dimethylacetamide, 1,3- dioxolane, or tetrahydrofuran.

The reaction of the anhydride and the polyamine or the anhydride and the mono-imide of step (a) of the presently claimed method can be conducted at a temperature ranging from about -10°C to about ambient (room) temperature.

Preferably, the reaction temperature is about 10°C to about ambient temperature. The time required for completion of the step (a) reaction can range from about 0.1 minute to about 4 hours, depending on the particular anhydride, polyamine, mono-imide, or solvent used, as well as the temperature of the reaction. The reaction is preferably run under nitrogen.

Alternatively, step (a) can in effect be obviated or carried out simultaneously with step (b) by mixing the reactants directly at the elevated temperature of step (b) . Thus, when step (b) is carried out using a continuous flow system, as described below, the reactants of step (a) can be pumped directly into the high temperature segment of the continuous flow system tube.

The heating step (b) of the present method is carried out in a precisely controlled manner which is effective to cyclize and dehydrate the bis-acid/amide or imide- acid/amide intermediate to form the desired symmetrical or unsymmetrical bis-imide compound in high purity, thereby to reduce the formation of undesired side products or impurities .

Cyclization and dehydration of the bis-acid/amide or imide-acid/amide intermediates to form the imide products are effected by heating the intermediates produced by the reaction described above under conditions effective to produce the bis-imide compound of Formula I, V or IX having a purity in the reaction of greater than about 80%. Preferably the reaction of the present method of synthesis yields the bis-imide compound of Formula I, V or IX in purity of greater than about 95%.

The heating step (b) of the present invention is preferably carried out using a continuous flow system, wherein the reactants and/or intermediates of the reaction flow through a hollow tube. A segment of the tube (the heated segment of the tube) is maintained at the desired heating temperature for the heating step. The tube diameter, tube length (of the heated segment) , flow rate, and heating temperature are selected so as to provide the desired residence time of the reactants and/or intermediates at the heating temperature so as to obtain the desired bis-imide product in purity of greater than 80%. After the reaction flows through the heated segment of the tube, the reaction may be cooled by flow into a tube or container of reduced temperature.

The tube for the continuous flow system may be of any shape, but is preferrably circular or oval in shape. The tube of the continuous flow system may be fabricated of any material capable of transferring heat from the outer surface of the tube to the inner surface of the tube. Exemplary tube materials include metal or glass. Preferably, the tube is fabricated from a metal alloy. The physical characteristics of the tube are chosen such that a rapid and uniform heating of the bis-acid/amide or imide-acid/amide intermediate can be effected. Preferred physical characteristics for the tube are an inside diameter (or average or effective diameter for a non- circular shaped tube) of about 0.05 cm to about 3 cm and having a tube wall thickness of about 0.02 cm to about 0.5 cm. The heated segment of the tube may have a length of about 0.3 m to about 15 m.

A representative tube for use in a continuous flow system useful in the method of the invention is a nickel-based, corrosion-resistant metal alloy tubing or coil which can be obtained under the tradename Hastelloy C® from the Stellite Rod Division of Stoody Deloro Stellite, Inc., Industry, CA.

The hollow tube may be heated by any material capable of transferring heat from a heat source to the hollow tube. Preferably, the hollow tube is immersed in a heating bath. The tube may also be heated in a convection oven. Most preferably, the heating bath contains a heat transfer material which can be stably maintained at a desired temperature such as oil, sand or glass beads. A particularly preferred heat transfer material is oil.

The temperature of the heating bath (i.e., the temperature at which step (b) is carried out) is that which, in combination with the residence time of the bis-acid/amide or imide-acid/amide intermediates, is effective to cyclize and dehydrate the bis-acid/amide or imide-acid/amide intermediate to yield the desired compound of Formulas I, V, or IX yet avoid formation of side products, so as to obtain the desired compound of Formulas I, V, or IX with a purity of greater than about 80% (preferably a purity of greater than about 95%) . Preferably, the temperature used in the heating step (b) of the present method is about 80°C to about 160°C. Using the continuous flow system, following the heating residence time the reaction solution is preferably immediately removed from the heated medium (i.e., the reaction solution is cooled) .

The bis-acid/amide intermediates are maintained in the tube for a residence time sufficient to convert them to the desired compound of Formula I, V or IX. Preferably, a flow rate of about 0.1 to about 500 mL/min is used to provide a residence time of about 0.1 min to about 4 hours, preferably about 0.25 min to about 10 min, depending on the temperature of the heating step. Flows through the hollow tube can be achieved by conventional techniques such as an HPLC pump.

The continuous flow system allows the cyclization/dehydration reaction time and temperature to be controlled more precisely and reliably than in a bulk solution reaction in a single container. Such precise and reliable control of reaction conditions allows the optimization of the reaction to maximize production of the desired bis-imide products and minimize the formation of undesired side products.

The purity of the compounds of Formula I, V, or IX obtained in the reaction of the present method is measured by standard analytical HPLC methods . The HPLC measurement of purity is determined on the dried product of the reaction of step (a) and (b) of the method of the present invention. The eluate of the HPLC is monitored using standard UV detection and the purity is measured as the relative peak area of the product.

The reaction of the present method for the synthesis of symmetrical bis-imide compounds of Formula I is preferably carried out using about 1 equivalent of the polyamine and about 2 equivalents of the anhydride. As will be appreciated by one of skill in the art of organic synthesis, the method of the present invention can be carried out with somewhat more or less than preferred stoichiometric amounts of the reactants to obtain the desired bis-imide products. Thus, the amount of each reactant can be varied to some extent from the preferred proportion of 1 equivalent of the polyamine and about 2 equivalents of the anhydride. The relative amounts of reactants in the method of the present invention could be varied, for example, by from 0 to about 20% from these preferred proportions.

Similarly, in the method of the present invention for the synthesis of unsymmetrical bis-imides of Formula V or Formula IX the reaction is preferably carried out using about 1 equivalent of the mono-imide and about 1 equivalent of the anhydride. As will be appreciated by one of skill in the art of organic synthesis, this reaction can also be carried out with somewhat more or less than these preferred stoichiometric amounts of the reactants. Thus, the amount of each reactant can be varied to some extent from the preferred proportion of 1 equivalent of the mono-imide and about l equivalent of the anhydride. The relative amounts of reactants in the method of the present invention could be varied, for example, by from 0 to about 20% from these preferred proportions.

The free base form of the symmetrical or unsymmetrical cyclized bis-imide product of Formula I, V, or IX yielded by the method of the present invention can be precipitated by adding the compound to water. The resulting suspension can then be filtered to isolate the free base form of the compound of Formula I, V, or IX. A pharmaceutically acceptable salt can be generated by acidifying the isolated free base with a mineral or organic acid in an organic solvent from which the salt form will precipitate, such as but not limited to ethanol, methanol, isopropanol, tetrahydrofuran, or acetonitrile.

Alternatively, the salt form of the bis-imide of Formula I, V, or IX can be generated directly by addition of the free base form of the bis-imide compound to a solution of a mineral acid or an organic acid in an organic solvent in which the salt form will precipitate, such as but not limited to tetrahydrofuran or acetonitrile. Preferably, the acid is methanesulfonic acid and the solvent is tetrahydrofuran.

By "symmetrical bis-imide" as used herein, it is meant a bis-imide compound of Formula I wherein the imide moieties derived from the anhydride (also referred to as the chromophores) are identical in structure. Thus, the symmetrical bis-imide is prepared by reaction of the polyamine with a single anhydride.

By "unsymmetrical bis-imide" as used herein, it is meant a bis-imide compound of Formula V or IX wherein the imide moieties (also referred to as the chromophores) derived from anhydrides are different in structure. Thus, the unsymmetrical bis-imide is prepared by reaction of the polyamine with two anhydrides which differ in structure.

The symmetrical bis-imide compounds produced by the method of the invention are represented by Formula I:

(I) or enantiomeric or diastereomeric forms thereof, or mixtures of enantiomeric or diastereomeric forms thereof, or pharmaceutically acceptable salts thereof, wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are inder ndently selected from H, CH3, or C2H5;

X is H or NO2;

Q and Z are H or may be taken together with the carbon atoms to which they are attached to form: a substituted or unsubstituted benzene ring, the substituents being 1 to 4 R-*-^*; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, 0 or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R-; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; each R⁶ is independently C1-C4 alkyl, OR⁷, S(0)qR⁷, N(R⁷)2, NO2, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

provided that at least one of R¹¹ or R²⁶ is CH₃ or C2H5.

Preferred compounds of Formula I are those described above wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H or CH3; provided that at least one of R¹¹ or R²⁶ is CH3; X is N0₂ ; and

Q and Z are H or together with the carbon atoms to which they are attached form a substituted or unsubstituted six-membered heterocyclic ring containing 1 N heteroatom, the heterocyclic ring substituents being 1 to 2 R---; and

R⁶ is CH3.

More preferred are compounds of Formula I wherein:

R¹¹ and R²⁶ are CH3;

R¹², R¹⁹, R²³, R⁴, R²⁰, and R⁵ are H;

X is NO2; and

Q and Z are H.

The method for synthesizing the symmetrical bis-imide compounds of Formula I comprises the steps of:

(a) reacting two equivalents of an anhydride of Formula II:

(ID where X, Q, and Z are as defined above, with one equivalent of a polyamine of Formula III

( III ) where R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are as defined above, in a suitable solvent; and

(b) heating the reaction under conditions effective to produce the bis-imide compound of Formula I; wherein step (b) yields the symmetrical bis-imide of Formula I in purity of greater than 80%.

The method of the present invention for synthesizing the symmetrical bis-imide compounds of Formula I also includes a method comprising the steps of:

(a) reacting two equivalents of an anhydride of Formula

(ID where X, Q, and Z are as defined above,

with one equivalent of a polyamine of Formula III:

(III)

where R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are as defined above, in a suitable solvent to yield one or more bis-acid/amide intermediate (s) selected from compounds of Formula IVa, IVb, IVc, or IVd:

( IVb) ;

( IVc) ;

( IVd) ; and

(b) heating the reaction products of step (a) under conditions effective to produce the bis-imide compound of Formula I; wherein step (b) yields the symmetrical bis-imide of Formula I in purity of greater than 80%.

As indicated, the intermediate bis-acid/amide product of Formula IV may include one or more of any of four regioisomers (IVa-IVd) .

The present invention also includes methods for the synthesis of symmetrical bis-imide compounds of Formula I and pharmaceutically acceptable salt forms thereof, comprising steps (a) and (b) above, and further comprising the steps of:

(c) adding the products of step (b) to water to precipitate the free base of the compound of Formula I; (d) filtering the precipitate of step (c) to isolate the free base of the compound of Formula I; and (e) acidifying the isolated free base of the compound of Formula I with a mineral acid or an organic acid to yield a pharmaceutically acceptable salt thereof.

The present invention also includes methods for the synthesis of symmetrical bis-imide compounds of Formula I and pharmaceutically acceptable salt forms thereof, comprising steps (a) and (b) above, and further comprising the step of:

(c) adding the products of step (b) to a solution of a mineral acid or an organic acid in an organic solvent to yield a pharmaceutically acceptable salt of the compound of Formula I.

Particularly preferred compounds of Formula I prepared by the method of the invention are compounds selected from:

(S,S)-2,2 '-[1,2-ethanediylbis [imino (1-methy1-2, 1- ethanediyl) ■ ]-bis [5-nitro-lH-benz [de] isoquinoline- l,3(2H)-d. ,.e]; (racemic + meso) -2,2 '- [1, 2-ethanediylbis [imino (1-methyl- 2, 1-ethanediyl) ] ]-bis [5-nitro-lH-benz [de]isoquinoline- 1,3 (2H)-dione] ; •♦

(R,R) -2, 2 '- [1,2-ethanediylbis [imino (l-methyl-2, 1- ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline- l,3(2H)-dione] ;

(meso) -2,2'- [1,2-ethanediylbis [imino(l-methyl-2, 1- ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline-1, 3 (2H) - dione] .

The present invention includes methods for the synthesis of unsymmetrical bis-imide compounds of Formula V comprising the steps of: (a) reacting one equivalent of an anhydride of Formula Ila or VII with one equivalent of a mono-imide of Formula VI in a suitable solvent to form a imide-acid/amide compound of Formula Vllla-VIIId; and (b) heating the reaction product of step (a) under conditions effective to cyclize and dehydrate the imide-acid/amide of Formula Vllla-VIIId; wherein step (b) yields the unsymmetrical bis-imide of Formula V in purity of greater than 80%.

The unsymmetrical bis-imide compounds produced by the method of the invention are represented by Formula V:

(V) or enantiomeric or diastereomeric forms thereof, or mixtures of enantiomeric or diastereomeric forms thereof, or pharmaceutically acceptable salts thereof, wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H, CH3, or C2H5;

X is H or NO2;

Q and Z are H or may be taken together with the carbon atoms to which they are ^attached to form: a substituted or unsubstituted benzene ring, the substituents being 1 to 4 R^*-*; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, 0 or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R^; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; each R6 is independently C1-C4 alkyl, OR⁷, S(0)qR⁷, N(R⁷)2r NO2, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

provided that at least one of R¹¹ or R²⁶ is CH3 or (^' H5;

D is an imide selected from

X¹ is H or N02 ;

Q¹ and Z¹ are H or may be taken together with the carbon atoms to which they are attached to form: a substituted or unsubstituted benzene ring, the subsituents being 1 to 4 R^; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, 0 or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R^β; each R⁶ is independently C1-C4 alkyl, OR⁷, S(0)qR⁷, N(R⁷)2, N02, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

R¹³, R¹⁴, R^15a, R^16a, R^17a, and R^18a are independently selected from: H, S(0)_nR^21a, C₁-C₆ alkyl, Ci-Cβ alkenyl, trihalomethyl, aryl, halogen, Ci-Cg alkoxy, hydroxy, a ino, C₁-C6 di- or mono- alkylamino, Ci-Cg alkylcarbonyl, C₁-C₇ carboalkoxy, formyl, cyano, nitro; and

R^21a is selected from Cχ-C6 alkyl or aryl;

n is 0, 1, or 2;

b, the bond between carbon atoms substituted with R¹³ and R^15a, may be a single or double bond; when b is a double bond, R¹³ and R^15a are substituted as stated above, and R¹⁴ and Rlδa do not exist.

Preferred compounds of Formula V are those described above wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H, CH3, or C2H5; provided that at least one of R¹¹ or R²⁶ is CH3;

X is NO2; D is

Q and Z are H; X¹ is H or NO₂;

Q¹ and Z¹ are H or together with the carbon atoms to which they are attached form a substituted or unsubstituted six-membered heterocyclic ring containing 1 N heteroatom, the heterocyclic ring substituents being 1 to 2 R6; and R⁶ is CH3.

Further preferred compounds of Formula V are those wherein:

R¹¹ and R²⁶ are CH3; R¹², R¹⁹, R²³, R⁴, R²⁰, and R⁵ are H; X is NO2; Q and Z are H. D is

Q and Z are H;

X¹ is H or NO2;

Q¹ and Z¹ are H or together with the carbon atoms to which they are attached form a substituted or unsubstituted six-membered heterocyclic ring containing 1 N heteroatom, the heterocyclic ring substituents being 1 to 2 R^; and

R⁶ is CH3.

Also preferred compounds of Formula V wherein:

R¹¹, R¹², R^l , R²³, R⁴, R °, R⁵- and R²^ are independently selected from H, CH₃, or C2H5; provided that at least one of R¹¹ or R²⁶ is CH3; X is NO2; D is

Q and Z are H;

R¹³, R¹⁴, R^15a, R^16a, R^17a, and R^18a are H; b is a single bond.

The method of the present invention for synthesizing the unsymmetrical bis-imide compounds of Formula V comprises the steps of: (a) reacting one equivalent of a mono-imide of Formula

(VI )

and one equivalent of an anhydride of Formula Ila:

(Ila)

or Formula VII

in a suitable solvent; and

(b) heating the reaction product of step (a) under conditions effective to produce the bis-imide compound of Formula V; wherein step (b) yields the unsymmetrical bis-imide of Formula V in purity of greater than 80%.

The method of the present invention for synthesizing the unsymmetrical bis-imide compounds of Formula V also includes a method which comprises the steps of : (a) reacting one equivalent of a mono-imide of Formula

(VI ) :

(VI )

and one equivalent of an anhydride of Formula Ila:

(Ila)

or Formula VII

in a suitable solvent, to yield one or two bis-imide-acid/amide intermediates selected from compounds of Formula Villa or VHIb:

(Villa) ;

or to yield one or two bis-imide-acid/amide intermediates selected from compounds of Formula VIIIc or VIlid:

(VIIIc) ;

and

(b) heating the reaction product of step (a) under conditions effective to produce the bis-imide compound of Formula V; wherein step (b) yields the unsymmetrical bis-imide of Formula V in purity of greater than 80% .

As indicated, the intermediate imide-acid/amide products of Formula VIII may include one or more of any of two regioisomers (Villa and/or VIIlb or VIIIc and/or viiid) .

The present invention also includes methods for the synthesis of unsymmetrical bis-imide compounds of Formula V and pharmaceutically acceptable salt forms thereof, comprising steps (a) and (b) above, and further comprising the steps of: (c) adding the products of step (b) to water to precipitate the free base of the compound of Formula V;

(d) filtering the precipitate of step (c) to isolate the free base of the compound of Formula V; and

(e) acidifying the isolated free base of the compound of Formula V with a mineral acid or an organic acid to yield a pharmaceutically acceptable salt thereof.

The present invention also includes methods for the synthesis of unsymmetrical bis-imide compounds of Formula V and pharmaceutically acceptable salt forms thereof, comprising steps (a) and (b) above, and further comprising the step of:

(c) adding the products of step (b) to a solution of a mineral acid or an organic acid in an organic solvent to yield a pharmaceutically acceptable salt of the compound of Formula V.

Specifically preferred bis-imide products which may be synthesized using the method of the present invention are compounds selected from the following: (R,R)-1- [2- (acenaphthene-5, 6-dicarboximido) - propylamino]-2- [2- (3-nitronaphthalene-l, 8- dicarboximido) -propylamino]ethane;

(S, S)-l- [2- (acenaphthene-5, 6-dicarboximido) - propylamino]-2- [2- (3-nitronaphthalene-l, 8- dicarboximido) -propylamino]ethane;

(R,S)-1- [2- (acenaphthene-5, 6-dicarboximido) propylamino]-2- [2- (3-nitronaphthalene-l, 8-dicarboximido) propylamino]ethane; (S,R)-1- [2- (acenaphthene-5, 6-dicarboximido) propylamino]-2- [2- (3-nitronaphthalene-l, 8-dicarboximido) propylamino]ethane;

(R,R)-1,2-bis- [2- (3-nitro-5-azaphenanthrene-l, 10- dicarboximido)propylamino]ethane;

(R,R)-1, 2-bis- [2- (3-nitro-7-methyl-5- azaphenanthrene-1, 10- dicarboximido)propylamino]ethane;

(S, S)-1,2-bis- [2- (3-nitro-5-azaphenanthrene-l, 10- dicarboximido)-1-methylethylamino]ethane;

(R,R)-l,2-bis-[2-(3-nitro-7-methyl-5- azaphenanthrene-1, 10-dicarboximido)propylamino]-

(R)-1-methylethane;

(R,R)-1- [2-(5-azaphenanthrene-l, 10- dicarboximido)propylamino]-2- [2- (3- nitronaphthalene-1, 8- dicarboximido)propylamino]ethane;

(R,R)-1-[2-(3-nitro-7-methyl-5-azaphenanthrene-

1, 10-dicarboximido)propylamino]-2- [2- (3-nitro- naphthalene-1, 8-dicarboximido)propylamino]ethane;

(R,R)-1- [2- (6-azaphenanthrene-l, 10- dicarboximido)propylamino]-2- [2- (3- nitronaphthalene-1, 8- dicarboximido)propylamino]ethane; (R,R)-1- [3-nitro-6-azaphenanthrene-l, 10- dicarboximido)propylamino]-2- [2- (3-nitro-naphthalene-l, £ dicarboximido)propylamino] ethane;

(R,R) -2-{2- [2- ( (2- (1, 3-dioxo-lH-benz [de] -isoquinolin-2- (3H) -yl)-propylamino) )ethylamino] -1-methylethyl}-5- nitro-lH-benz [de] isoquinolin-1, 3- (2H) -dione; (S, S) -2-{2- [2- ( (2- (1, 3-dioxo-lH-benz [de] -isoquinolin-2- (3H)-yl)propylamino) ) ethylamino]-1-methylethyl}-5-nitro- lH-benz [de]isoquinolin-1,3-(2H)-dione;

(R,S)-2-{2-[2-( (2- (1, 3-dioxo-lH-benz [de]-isoquinolin-2- (3H)-yl)-propylamino) )ethylamino]-1-methylethyl}-5- nitro-lH-benz [de] isoquinolin-1,3- (2H) -dione; and (S,R)-2-{2- [2- ( (2- (1, 3-dioxo-lH-benz [de]-isoquinolin-2- (3H)-yl)-propylamino) )ethylamino]-1-methylethyl}-5- nitro-lH-benz [de] isoquinolin-1,3- (2H) -dione.

Additionally, the method of the invention can be used to prepare bis-imide compounds represented by Formula IX:

(IX) and pharmaceutically acceptable salts thereof, wherein: R¹⁵, R¹⁶, R¹⁷ and R¹⁸ are independently H, C1-C alkyl, 0R^19a, S(0)_rR^19ar N(R^19a)2, NO2, CN, F, Cl, Br, I, phenyl, CF3 or NHC (0)R^19a; each R^{1 a} is independently H, C3_.-C4 alkyl, phenyl or benzyl; Ql and Z--* together with the carbon atoms to which they are attached form: a substituted or unsubstituted benzene ring, the substituents being 1 to 4 R20^a; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, NH, 0 or S atoms, the heterocyclic ring substituents being 1 to 2 R20a_{; or} a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R20a_; each R20a ^→__s independently C1-C4 alkyl, OR^19a, S(0)_rR¹⁹ , N(R^19a)2, N02, CN, F, Cl, Br, I, phenyl, CF3 or NHC(0)R^19a; or Q-¹- and Z¹ may alternatively be taken together to form the group:

wherein one of G or J is C=0 and the other is C=0, NH, S or 0;

Z- and Q^^→ are optionally present and when present may join together to form: a substituted or unsubstituted benzene ring, the substituents being 1 to 4 R^^³; a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, NH, 0 or S atoms, the heterocyclic ring substituents being 1 to 2 R^0^a; a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R²-*-¹³; or the group:

wherein one of G--- or J¹ is C=0 and the other is C=0, NH, S or 0; or when Q² and Z² are not joined together and when R---6 is in the 4-position, then Q² and R¹-- may join together to form an ethylene bridge;

wherein A is NR²⁴ or

R21. R22_{? an}-_ R23a _are independently H, C1-C3 alkyl, allyl or CH2 , wherein L is OH, OCH3, CH2SCH3, (CH2)_rNH2 or phenyl; each R²⁴ is independently H, C1-C3 alkyl or allyl; m¹, m², m³, and m⁴ are independently 0 or 1, provided that at least two of m¹, m², m³, and m⁴ are 1; n¹, n², n³, and n⁴ are independently 0 or 1, provided that at least two of n¹, n², n³, and n⁴ are 1;

P¹/ P² r P³r and P⁴ are independently 0 or 1, provided that at least two of p¹, p², p³, and p⁴ are 1; and each r is independently 0, 1 or 2;

provided that at least one carbon atom alpha to the imide nitrogen in the polyamine linker is substituted with C1-C3 alkyl, allyl or CH2L, wherein L is OH, OCH3, CH2SCH3, (CH2)_rNH2 or phenyl.

Such compounds of Formula IX are prepared as described above for compounds of Formula V by selection of the appropriate mono-imide and anhydride reactants and heating the reaction so as to yield the desired product of Formula IX with a purity of greater than 80%.

The compounds herein described may have asymmetric centers. All chiral, diastereomeric, and racemic forms are included in the present invention. Any geometric isomers may be present in the compounds described herein, and all such stable isomers are contemplated in the present invention. All chiral, diastereomeric, racemic forms and all geometric isomeric forms of a structure are intended, unless the specific stereochemistry or isomeric form is specifically indicated.

When any variable (for example, R^19a, R²¹, R²², or R^23a) occurs more than one time in any constituent or in any formula herein, its definition on each occurrence is independent of its definition at every other occurrence. Combinations of substituents and/or variables in a chemical structure are permissible only if such combinations result in stable compounds . When a bond to a substituent is shown to cross the bond connecting two atoms in a ring, then such substituent may be bonded to any atom on the ring.

As used herein, "alkyl" is intended to include both branched and straight chain saturated aliphatic hydrocarbon groups having the specified number of carbon atoms; "alkoxy" represents an alkyl group of indicated number of carbon atoms attached through an oxygen bridge. "Alkenyl" is intended to include hydrocarbon chains of either a straight or branched configuration and one or more unsaturated carbon-carbon bonds which may occur in any stable point along the chain, such as ethenyl, propenyl, and the like.

The term "substituted", as used herein, means that one or more hydrogen on the designated atom is replaced with a selection from the indicated group, provided that the designated atom's normal valency is not exceeded, and that the substitution results in a stable compound. By "stable compound" or "stable structure" is meant herein a compound that is sufficiently robust to survive isolation to a useful degree of purity from a reaction mixture, and formulation into an efficacious therapeutic agent.

As used herein, the term "heterocycle" is intended to mean a stable 5- to 7- membered monocyclic ring which is either saturated or unsaturated, and which consists of carbon atoms and from 1 to 2 heteroatoms independently selected from the group consisting of N, O and S and wherein the nitrogen and sulfur heteroatoms may optionally be oxidized, and the nitrogen may optionally be quaternized.

The reaction product of the method of the present invention is the free base form of the compound of Formula I, V, or IX. The free base form of the compound of Formula I, V, or IX may be precipitated and converted to any desired pharmaceutically acceptable salt form. Alternatively, the reaction product of Formula I, V, or IX may be converted directly to the desired pharmaceutically acceptable salt form (without prior precipitation) by the addition of an appropriate mineral or organic acid to produce a pharmaceutically acceptable salt of the compound of Formula I, V, or IX. Thus, for example, methanesulfonic acid may be added to the compound of Formula I, V, or IX in a suitable solvent, to yield the methanesulfonic acid salt of the compound of Formula I, V, or IX.

Generally, pharmaceutically acceptable salts of the products of Formula I, V, or IX produced by the methods of the invention can be prepared by reacting the free base form of these compounds with a stoichiometric amount of the appropriate acid in water or in an organic solvent, or in a mixture of the two; generally, nonaqueous media like ether, tetrahydrofuran, ethyl acetate, ethanol, isopropanol, dichloromethane or acetonitrile are preferred. Lists of pharmaceutically acceptable salts are found in "Remington's Pharmaceutical Sciences", 17th ed., Mack Publishing Company, Easton, PA, p.1418 (1985), the disclosure of which is hereby incorporated herein by reference. The products of the present synthetic methods can be further purified by recrystallization from organic solvents such as CH3CN, CH3OH and a mixture of dimethylformamide (DMF) and tetrahydrofuran (THF), with or without water.

The starting materials (reactants) of Formula II, III, VI, Ila, and VII are prepared as disclosed in U.S. Patent 5,206,249 to Sun and copending, commonly assigned U.S. Patent Applications Serial Numbers 08/080,862, filed 6/24/93 (Patten et al. ) ; 07/805,045, filed 12/11/91 (Sun); PCT International Application Publication Number WO 93/12092 (Sun); 08/016,555, filed 2/11/93 (Cherr*~y and Seitz) ; and 08/016,553, filed 2/11/93 (Kaltenbach eτ. al.) . The disclosures of these references are hereby incorporated in their entirety by reference herein.

The disclosures of all the references cited herein are hereby incorporated herein in their entirety by reference.

The parent anhydrides of Formula II are commercially available or can be prepared according to the procedures described by Hodgson et al . in J. Chem . Soc , 90 (1945) or as described by Jones in "Comprehensive Heterocyclic Chemistry", Volume 2, 1984, p.395 or as described by Floyd et al . in Chem . Rev. 76, p.509 (1976) . The anhydrides of Formula VII can be prepared from electrophilic additions, as described by Eckert et al . in U.S. Patent No. 2,067,138, onto the parent anhydride, acenaphthalic acid anhydride. The unsaturated anhydride, 5, 6-acenaphthylenedicarboxylic anhydride, is also known along with the 1,2-dibromo-5, 6-acenaphthylene-dicarboxylic anhydride from Trost et al . in J. Org . Chem . , p.2620 (1967) and in J. Amer . Chem . Soc , p. 918 (1969) . The 1,2-dibromo derivative can be substituted using standard chemistry techniques such as those disclosed by Stille in Angew. Chem. Int . Ed. Engl . , p.508 (1986) to yield the 1,2- dicarbomethoxy, 1,2-dicyano, 1,2-dialkenyl, 1,2-dialkyl, 1,2-diaryl, 1,2-dihalo and the 1, 2-dialkylamino-5, 6- acenaphthylenedicarboxylic anhydride. The 1-substituted and 1, 1-disubstituted acenaphthalic acid anhydrides can be obtained by methods similar to those mentioned above from the parent anhydride after benzylic bromination.

Procedures for the synthesis of the diastereomeric or enantiomeric forms of the polyamine linker in compounds of Formula III or mixtures of enantiomeric or diastereomeric forms thereof are described in U.S. Patent No. 5,206,249 to Sun.

U.S. Patent No. 5,206,249 to Sun discloses synthetic methods for the compounds of Formula I where the reaction of the anhydride and polyamine is carried out by reflux of the reactants in a single container using conventional laboratory glassware (i.e., a round bottom flask) . It has been determined that the prior art method for the synthesis of the compounds of Formula I, V, and IX results in the formation of significant amounts of undesired side products from which the desired symmetrical or unsymmetrical bis- imide products must be separated by column chromatography. Such side products may result from side reactions, thermal decomposition, or oxidation of the compounds of Formula I, V or IX and impurities in the starting materials. The purity of the symmetrical bis-imide product obtained for the reaction of the anhydride and polyamine as disclosed in the prior art is about 57%.

In contrast, in the method of the present invention, it has been found that the desired bis-imide product may be obtained having a purity of greater than about 80% and preferably greater than about 95%, and still more preferably >98.5%.

The present invention is further described in the following specific, non-limiting Examples.

EXAMPLES

The following Examples describe the synthesis of the representative bis-imide (R,R)-2, 2- [1, 2- ethanediylbis [imino(l-methyl-2, 1-ethanediyl) ] ]-bis- [5- nitro-lH-benz [de]isoquinoline-1,3-(2H) -dione (MW 624.61) and its methanesulfonate salt. The starting materials were 3-nitro-l,8-naphthalic anhydride (MW 243.17) and (R,R)- N-^N¹'-!, 2-ethanediylbis [1, 2-propanediamine] (MW 174.29) . Example 1 compares crude product purity from approximately 3 mmol syntheses performed by the method of the prior art and according to the method of the present invention. Examples 2 and 3 describe an approximately 14 mmol synthesis where the dehydration and cyclization of the ac;^*1/amide intermediate were conducted by the method of the present invention in a metal tube having a 5 mL internal volume. Example 4 describes an approximately 1 mole synthesis where the dehydration and cyclization of the acid/amide intermediate were conducted in a 76.4 mL Hastelloy C® tube.

Example 1

A mixture of 3-nitro-l,8-naρhthalic anhydride (1.62 g, 6.7 mmol) and (R,R)-N¹,N¹ '-1,2-ethanediylbis [1,2- propanediamine] (0.58 g, 3 . 3 mmol) in 80 ml ethanol was stirred at room temperature for 48 hours. The mixture was then heated to reflux for 2 hours . The mixture was cooled to room temperature overnight and the solvent evaporated to dryness in vacuo at 78°C for 2 hours. 2.16 g of the crude product having a purity of 57.1% by HPLC was obtained. NMR spectra showed many impurity peaks were present . To a suspension of 3-nitro-l, 8-naphthalic anhydride (1.62 g, 6.7 mmol) in 15 mL DMSO cooled with a tap water bath, there was added, under nitrogen, 0.58 g (3.3 mmol) of (R,R)-N¹,N¹ '-1,2-ethanediylbis [1,2- propanediamine] in 5 mL of DMSO. After one hour, the water bath was removed and the solution stirred at room temperature for 3 hours. Thin layer chromatography analysis in methanol/methylene chloride (1/9) showed that all of the anhydride had been consumed and only the bis- acid/amide was present. The solution was then passed through a tube having a 5 mL internal volume immersed in an oil bath maintained at 149°C at a flow rate of 5 mL/min. An additional 15 mL DMSO was passed through the tube to ensure that the product was completely eluted. The solution was poured into 50 mL water and the resulting precipitate collected by filtration. The crude product was dried in vacuo at 78°C for two hours and then at room temperature overnight to give 1.71 g of the crude product having a purity of 89.9% by HPLC. NMR spectral analysis also showed that the product obtained using the continuous flow system had less impurities than the product prepared by the conventional reflux method described above.

-34-

SUBST1TUTE SHEET (RULE 26) The purity of the dried bis-imide product was determined by HPLC using: an E-Merck Lichrosphere 60-RP Select-B, 4 mm i.d. x 125 mm column; column temperature of 35°C; flow rate of 1.5 mL/min; UV detection at 272 nm; mobile phases 30% CH3CN + 70% aqueous solution containing triethylamine (0.15%), phosphoric acid (0.15%) and sodium hexasulfonate (0.01 M) .

F.xa ple ?

To a suspension of 3-nitro-l, 8-naphthalic anhydride (6.97 g, 28.6 mmol) in 80 mL of DMSO cooled with a tap water bath (about 20°C) , there was added 2.50 g (14.3 mmol) of (R,R) -N^N--- '-1,2-ethanediylbis [1, 2-propanediamine] (III) under nitrogen. After one hour, the water bath was removed and the mixture stirred at room temperature for 3 hours. The solution was pumped through a 5 mL stainless steel HPLC sample loop tube obtained from Rheodyne (catalog number 7029) immersed in an oil bath maintained at 149-151°C at a flow rate of 5 mL/min. The stainless steel tube had an inside diameter of 0.1 cm (0.04 inch) and a length of 6.17 m (20.2 feet) . An additional 20 mL of DMSO was pumped through the tube to ensure that no product was retained within the tube. The combined dark DMSO solution (total 100 mL) was poured into 300 mL of water. The resulting precipitates were collected on a filter, washed with water and dried at 66°C under vacuum to give 8.9 g of the free base. This free base was dissolved in 100 mL of THF and cooled with a tap water bath (about 20°C) . To the dissolved free base there was added 2.80 g (29.1 mmol) of methanesulfonic acid in 50 mL of THF. After stirring at ambient temperature overnight, the solid was collected on a filter, washed with THF (180 mL) and dried to give 11.15 g (95.5%) of the methanesulfonate salt. The crude product was recrystallized from 400 L of aqueous acetonitrile

(CH3CN/H2O = 7/1), treated with 10 g of charcoal, filtered through a silica gel and Celite® pad, washed with aqueous acetonitrile and filtered. The solvents in the filtrate were reduced to about 50 mL. After standing overnight, the solid was collected on a filter, washed with cold acetonitrile and dried to give 7.8 g (66.8%) of the methanesulfonate salt of (I), mp 224-225.5°C (d) . The product was further purified by a second recrystallization without charcoal to give 5.82 g (49.8%) of I, mp 227- 228.5°C. NMR (DMSO-d6) δ 9.59 (d, 2H, J=2.2 Hz, aromatic protons), 9.02 (d, 2H, J=2.2 Hz, aromatic protons), 8.88

(d, 2H, J=8.4 Hz, aromatic protons), 8.96-8.79 (broad, 4H, 2NH2⁺) , 8.76 (d, 2H, J=7.0 Hz, aromatic protons), 8.16 (2 d, 2H, J=7.7, 8.0 Hz), 5.53 (m, 2H, 2 CH) , 3.93 (t, 2H, J=11.2 Hz), 3.52 (broad, 2H) , 3.36 (broad, 4H) , 2.26 (s, 6H, 2 CH3) and 1.64 (d, 6H, J=7.0 Hz, 2 CH3) IR (KBr)

3442, 2980, 2936, 2754, 1710, 1668, 1600, 1538, 1420, 1368, 1344, 1328, 1248, 1202, 1086, 1074, 1060, 796 and 786 cm^-1. [α]o -38.08° (c=0.604, DMF) .

Alternatively, the DMSO solution coming out of the tube was added to a solution of methanesulfonic acid (4.13 g, 43 mmol) in 200 mL of THF. After standing overnight, the precipitates were collected on a filter, washed with THF and dried to give 10.1 g (85.5%) of the crude product. This was purified by recrystallization from aqueous acetonitrile twice to give 4.67 g (40.4%) of the methanesulfonate salt of (I), mp 224-226°C (d) . The NMR spectrum was identical to that described above.

The purity of the dried bis-imide product was determined by HPLC using: a Zorbax RX-C8, 4.6 mm i.d. x 25 cm; column temperature of 35°C; flow rate of 2.0 mL/min; UV detection at 270 nm. The mobile phases, gradient profile, and sample preparation are described as follows.

Mobile Phase A: Dissolve 0.87 grams of sodium pentanesulfonate in 880 mL of water. Add 70 mL of acetonitrile, 50 mL of tetrahydrofuran, 1.00 mL of triethylamine and 1.00 mL of phosphoric acid and mix thoroughly. Filter the mobile phase through a 0.45- micron filter and degas.

Mobile Phase B: Dissolve 0.87 grams of sodium pentanesulfonate in 450 mL of water. Add 500 mL of acetonitrile, 50 mL of tetrahydrofuran, 1.00 mL of triethylamine and 1.00 mL of phosphoric acid and mix thoroughly. Filter the mobile phase through a 0.45- micron filter and degas . Gradient Profile:

Time (min) %A %B

0 100 0

25 50 50 35 0 100

35.1 100 0

Sample Preparation: Accurately weigh approximately 50 mg of dry reaction product into a 50-mL volumetric flask and add about 30 mL of solvent (a 1:1 mixture of acetonitrile and 0.01 N hydrochloric acid) to the flask. Sonicate the sample solution for 1 or 2 minutes to break up any large particles and shake until completely dissolved. Bring to volume with solvent.

Example 3

To a suspension of 3-nitro-l, 8-naphthalic anhydride (6.95 g, 28.5 mmol) in 30 mL of DMSO cooled with a tap water bath (about 20°C) , there was added 2.49 g (14.2 mmol) of (R,R) -N¹,N¹ '-1, 2-ethanediylbis [1, 2-propanediamine] under nitrogen. After one hour, the water bath was removed and the mixture stirred at room temperature for 3 hours. The solution was pumped through a 2.07 m (6 feet, 9.5 inches) tube of Hastelloy C® tubing having a 5 mL volume, a 0.3175 cm (0.125 inch) outside diameter, a 0.1753 cm

(0.069 inch) inside diameter and a 0.0711 cm (0.028 inch) wall thickness. In separate experiments, the tube was immersed in an oil bath maintained at either 130.5-131°C, 150-151°C or 160-161°C and the bis-acid/amide residence time in the tube was 1 minute, 2 minutes and 1 minute, respectively (at a flow rate of 5 mL/min for the 1 minute residence time and a flow rate of 2.5 mL/min for the 2 minute residence time) . An additional 20 mL of DMSO was pumped through the tube to ensure that no product was retained within the tube. The combined dark DMSO solution (total 100 mL) was poured into 150 mL acetonitrile containing 3 g of methanesulfonic acid. The resulting precipitates were collected on a filter, washed with acetonitrile and dried under nitrogen to yield the methanesulfonate salt . The crude yields and purity of the crude product as determined by HPLC are listed in Table 1.

Table 1.

Tube Temp. Residence Time Crude Yield Purity

130°C 1 minute 7.0 g 98.5 %

150°C 2 minutes 8.78 g 97.2%

160°C 1 minute 9.1 g 98.1%

xa ple ! 4

To a suspension of 3-nitro-l, 8-naphthalic anhydride (488.3 g, 2.0 moles) in 2.1 L of DMSO at 20-30°C, there was added 175 g (1.0 mole) of (R,R) -N-^N¹ '-1, 2- ethanediylbis [1, 2-propanediamine] . The mixture was stirred for 30 minutes at room temperature. The solution was passed through a fritted filter funnel and pumped through a 20 foot tube of Hastelloy C® tubing having an internal volume of 76.4 mL immersed in an oil bath maintained at 150±0.5°C at a flow rate of 42-43 mL/min. The total residence time of the reaction mixture in the tube was about one minute. The Hastelloy C® tube had an outside diameter of 0.4763 cm (0.1875 inch), an inside diameter of 0.3995 cm (0.1175 inch) and a wall thickness of 0.0889 cm (0.035 inch) . The DMSO solution exiting the tube was added directly to a 22 L flask containing 10.5 L of acetonitrile and 142 mL of methanesulfonic acid. The methanesulfonate salt of the product formed as a brown precipitate, was isolated by removing the mother liquor by suction through a filter stick and washed three times with a total volume of 9 L of acetonitrile. The purity of the crude product after drying was 95-98%, as determined by HPLC. The product was further purified by recrystallization from acetonitrile/water (7/1 v/v, 75 -C) . Yield was 60% of theoretical of white to light yellowish powder.

The present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof and, accordingly, reference should be made to the appended claims as further indicating the scope of the invention.

Claims

WHAT IS CLAIMED IS:

1. A method for preparing bis-imide compounds of Formula I:

(I) or enantiomeric or diastereomeric forms thereof, or mixtures of enantiomeric or diastereomeric forms thereof wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H, CH₃, or C2H5;

X is H or NO2;

Q and Z are H or may be taken together with the carbon atoms to which they are attached to form: a substituted or unsubstituted benzene ring, the substituents being 1 to 4 R---; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, 0 or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; each R⁶ is independently C1-C4 alkyl, OR⁷, S(0)qR⁷, N(R⁷)2, NO2, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

provided that at least one of R¹¹ or R²⁶ is CH3 or C2H5;

said method comprising the steps of:

(a) reacting two equivalents of an anhydride of Formula II:

(II) where X, Q, and Z are as defined above, with one equivalent of a polyamine of Formula III:

(III)

where R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are as defined above, in a suitable solvent; and

(b) heating the reaction under conditions effective to produce the bis-imide compound of Formula I; wherein step (b) yields the symmetrical bis-imide of Formula I in purity of greater than 80% . A method according to Claim 1 wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H or CH3; provided that at least one of R¹¹ or R²⁶ is CH3;

X is NO2; and

Q and Z are H or together with the carbon atoms to which they are attached form a substituted or unsubstituted six-membered heterocyclic ring containing 1 N heteroatom, the heterocyclic ring substituents being 1 to 2 R^; and

R⁶ is CH3.

A method according to Claim 1 wherein;

R¹¹ and R²⁶ are CH₃;

R¹², R¹⁹, R²³, R⁴, R²⁰, and R⁵ are H;

X is NO2; and

Q and Z are H.

4. A method for preparing bis-imide compounds of Formula I :

(I) or enantiomeric or diastereomeric forms thereof, or mixtures of enantiomeric or diastereomeric forms thereof, wherein: R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H, CH3, or C2H5;

X is H or NO2;

Q and Z are H or may be taken together with the carbon atoms to which they are attached to form: a substituted or unsubstituted benzene ring, the substituents being 1 to 4 R"; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, 0 or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; each R⁶ is independently C1-C4 alkyl, OR⁷, S(0)qR⁷, N(R⁷)2, N02, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

provided that at least one of R¹¹ or R²⁶ is CH3 or C2H5;

said method comprising the steps of:

(a) reacting two equivalents of an anhydride of Formula II:

(ID where X, Q, and Z are as defined above,

with one equivalent of a polyamine of Formula III

( II I )

where R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are as defined above,

in a suitable solvent to yield one or more bis-acid/amide intermediate selected from compounds of Formula IVa, IVb, IVc, or IVd:

( IVb) ;

( IVc) ;

I IVd) ; and

(b) heating the reaction products of step (a) under conditions effective to cyclize and dehydrate the intermediate to produce the bis-imide compound of Formula I; wherein step (b) yields the symmetrical bis-imide of Formula I in purity of greater than 80%

5. A method according to Claim 4 wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R5. and R²⁶ are independently selected from H or CH3; provided that at least one of R¹¹ or R²⁶ is CH3;

X is NO₂; and

Q and Z are H or together with the carbon atoms to which they are attached form a substituted or unsubstituted six-membered heterocyclic ring containing 1 N heteroatom, the heterocyclic ring substituents being 1 to 2 R6; and

R⁶ is CH3. 6. A method according to Claim 4 wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H or CH3; provided that at least one of R¹¹ or R²⁶ is CH3; X is NO2; and Q and Z are H.

7. A method according to Claim 4 wherein:

R¹¹ and R²⁶ are CH3;

R¹², R¹⁹, R²³, R⁴, R²⁰, and R⁵ are H;

X is NO2; and

Q and Z are H.

8. A method according to Claim 6 wherein the compound of Formula I is selected from:

(S, S)-2,2 '- [1,2-ethanediylbis [imino (l-methyl-2, 1- ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline- l,3(2H)-dione] ;

(racemic + meso)-2,2 '- [1,2-ethanediylbis [imino(1-methy1-

2, 1-ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline- l,3(2H)-dione] ; (R,R) -2, 2 '- [1,2-ethanediylbis [imino (l-methyl-2, 1- ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline- l,3(2H)-dione] ;

(meso) -2, 2 '- [1, 2-ethanediylbis [imino(l-methyl-2, 1- ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline- 1,3 (2H)-dione] ;

(S,S)-2,2 '- [1,2-ethanediylbis [imino (2-methyl-2, 1- ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline-

1,3 (2H) -dione] ;

(racemic + meso) -2 , 2 ' - [ 1 , 2-ethanediylbis [ imino (2-methyl- 2 , 1-ethanediyl) ] ] -bis [5-nitro-lH-benz [de ] isoquinoline- l , 3 (2H) -dione ] . 9. The method of Claim 7 wherein the compound of Formula I is (R,R)-2,2 '- [1,2-ethanediylbis [imino(1-methyl- 2, 1-ethanediyl) ] ]-bis [5-nitro-lH-benz [de] isoquinoline- l,3(2H)-dione] .

10. A method of Claim 1 or 4 wherein the heating step (b) is carried out by flow of the reaction solution through a hollow tube, said tube having a heated segment which is maintained at a temperature effective to yield the bis- imide product of Formula I with a purity of greater than 80%.

11. A method of Claim 1 or 4 wherein the heating step (b) is carried out by flow of the reaction solution through a hollow tube, said tube having a heated segment which is maintained at a temperature effective to yield the bis- imide product of Formula I with a purity of greater than 95%.

12. A method of Claim 1, 4, or 10 further comprising the steps of:

(c) adding the products of step (b) to water to precipitate a free base form of the compound of Formula I; (d) isolat_ng the free base form of the compound of Formula I; and

(e) acidifying the isolated free base of the compound of Formula I with a mineral acid or an organic acid to yield a pharmaceutically acceptable salt thereof.

13. The method of Claim 1 , 4, or 10 further comprising the steps of:

(c) adding the products of step (b) to a solution of a mineral acid or an organic acid in an organic solvent to yield a pharmaceutically acceptable salt of the compound of Formula I. 14. The method of Claim 12 wherein the acid is methanesulfonic acid.

15. The method of Claim 13 wherein the acid is methanesulfonic acid.

16. A method for preparing unsymmetrical bis-imide compounds of Formula V:

(V) or enantiomeric or diastereomeric forms thereof, or mixtures of enantiomeric or diastereomeric forms thereof, or pharmaceutically acceptable salts thereof, wherein:

R^U, R¹², R¹⁹, R²³, R⁴, R²°, R⁵, and R²⁶ are independently selected from H, CH₃, or C2H5;

X is H or NO2;

Q and Z are H or may be taken together with the carbon atoms to which they are attached to form: a substituted or unsubstituted benzene ring, the substituents being 1 to 4 R*--; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, 0 or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; each R⁶ is independently C1-C4 alkyl, OR⁷, S(0)qR⁷, N(R⁷)2, N02, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

provided that at least one of R¹¹ or R²⁶ is CH3 or C2H5;

D is an imide selected from:

X¹ is H or NO2;

Q¹ and Z¹ are H or may be taken together with the carbon atoms to which they are attached to form: a substituted or unsubstituted benzene ring, the subsituents being 1 to 4 R^; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, O or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R^*^; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; each R⁶ is independently C3_.-C₄ alkyl, OR⁷, S(0)qR⁷,

N(R⁷)2, N02, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

R¹³, R¹⁴, R^15a, R^16a, R^17a, and R^18a are independently selected from: H, S(0)_nR^21a, C₁-C₆ alkyl, C±-Ce alkenyl, trihalomethyl, aryl, halogen, Ci-Cβ alkoxy, hydroxy, amino, Cχ-C6 di- or mono- alkylamino, Ci-Cβ alkylcarbonyl, C₁-C₇ carboalkoxy, formyl, cyano, nitro; and

R^21a is selected from C₁-C6 alkyl or aryl;

n is 0, 1, or 2;

b, the bond between carbon atoms substituted with R¹³ and R^15a, may be a single or double bond; when b is a double bond, R¹³ and R^15a are substituted as stated above, and R¹⁴ and Rl6a do not exist;

said method comprising the steps of:

(a) reacting one equivalent of a mono-imide of Formula

(VI ) :

(VI )

and one equivalent of an anhydride of Formula Ila:

or Formula VII

(VII)

in a suitable solvent; and

(b) heating the reaction product of step (a) under conditions effective to produce the bis-imide compound of Formula V; wherein step (b) yields the unsymmetrical bis-imide of Formula V in purity of greater than 80% .

17. A method for preparing unsymmetrical bis-imide compounds of Formula V:

(V) or enantiomeric or diastereomeric forms thereof, or mixtures of enantiomeric or diastereomeric forms thereof, or pharmaceutically acceptable salts thereof, wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H, CH3, or C2H5;

X is H or NO2;

Q and Z are H or may be taken together with the carbon atoms to which they are attached to form: a substituted or unsubstituted benzene ring, the substituents being 1 to 4 R6; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, 0 or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R⁶; each R⁶ is independently C1-C4 alkyl, OR⁷, S(0)qR⁷, N(R⁷)2, N02, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

provided that at least one of R¹¹ or R²⁶ is CH₃ or C2H5;

D is an imide selected from:

X¹ is H or N02 ;

Q¹ and Z¹ are H or may be taken together with the carbon atoms to which they are attached to form: a substituted or unsubstituted benzene ring, the subsituents being 1 to 4 R^; or a substituted or unsubstituted five-membered heterocyclic ring containing 1 to 2 N, 0 or S heteroatoms, the heterocyclic ring substituents being 1 to 2 R^β; or a substituted or unsubstituted six-membered heterocyclic ring containing 1 to 2 N heteroatoms, the heterocyclic ring substituents being 1 to 2 R^β; each R⁶ is independently C1-C4 alkyl, OR⁷, S(0)qR⁷, N(R⁷)2, NO2, CN, F, Cl, Br, I, phenyl, CF3, or NHC(0)R⁷; each R⁷ is independently H, C1-C4 alkyl, phenyl or benzyl; and each q is independently 0, 1, or 2;

R¹³, R¹⁴, R^15a, R^16a, R^17a, and R^18a are independently selected from: H, S(0)_nR^21a, Cχ-C6 alkyl, Cχ-C6 alϋenyl, trihalomethyl, aryl, halogen, ι-C_ alkoxy, hydroxy, amino, Ci-Cβ di- or mono- alkylamino, Ci-Cβ alkylcarbonyl, C₁-C₇ carboalkoxy, formyl, cyano, nitro; and

R^21a is selected from Ci-Cβ alkyl or aryl;

n is 0, 1, or 2;

b, the bond between carbon atoms substituted with R¹³ and R^15a, may be a single or double bond; when b is

-53-

SUBST1TUTE SHEET (RULE 26) a double bond, R¹³ and R^15a are substituted as stated above, and R¹⁴ and Rl6a do not exist;

said method comprising the steps of:

(a) reacting one equivalent of a mono-imide of Formula

(VI ) :

(VI )

and one equivalent of an anhydride of Formula Ila:

(Ila)

or Formula VII

in a suitable solvent, to yield one or two bis-imide-acid/amide intermediates selected from compounds of Formula Villa or VHIb:

(Villa) ;

or to yield one or two bis-imide-acid/amide intermediates selected from compounds of Formula VIIIc or VIIId:

and (b) heating the reaction product of step (a) under conditions effective to produce the bis-imide compound of Formula V; wherein step (b) yields the unsymmetrical bis-imide of Formula V in purity of greater than 80% .

18. A method according to Claims 16 or 17 wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H or CH₃; provided that at least one of R¹¹ or R²⁶ is CH3; X is NO2; D is

Q and Z are H; X¹ is H or NO₂;

Q¹ and Z¹ are H or together with the carbon atoms to which they are attached form a substituted or unsubstituted six-membered heterocyclic ring containing 1 N heteroatom, the heterocyclic ring substituents being 1 to 2 R^; and R⁶ is CH3.

19. A method according to Claims 16 or 17 wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H or CH3; X is NO2; D is

Q and Z are H;

X¹ is H or NO₂;

Q¹ and Z¹ are H or may be taken together with the carbon atoms to which they are attached to form a substituted or unsubstituted six-membered heterocyclic ring containing 1 N heteroatom, the heterocyclic ring substituents being 1 to 2 R*-*; and

R⁶ is CH3.

20. A method according to Claims 16 or 17 wherein:

R¹¹, R¹², R¹⁹, R²³, R⁴, R²⁰, R⁵, and R²⁶ are independently selected from H or CH3; provided that at least one of R¹¹ or R²⁶ is CH3; X is NO₂; D is

Q and Z are H;

R¹³ , R¹⁴ , R^15a, R^16a, R^17a, and R^18a are H; b is a single bond . 22. A method according to Claim 19 wherein the unsymmetrical bis-imide product of Formula V is selected from the following:

(R,R)-l,2-bis-[2- (3-nitro-5-azaphenanthrene-l, 10- dicarboximido)propylamino] ethane; (R,R)-l,2-bis-[2-(3-nitro-7-methyl-5- azaphenanthrene-1, 10- dicarboximido)propylamino]ethane; (S,S)-1,2-bis-[2- (3-nitro-5-azaphenanthrene-l, 10- dicarboximido) -1-methylethylamino]ethane; (R,R)-1,2-bis- [2-(3-nitro-7-methyl-5- azaphenanthrene-1, 10-dicarboximido)propylamino]- (R)-1-methylethane; (R,R) -1- [2- (5-azaphenanthrene-l, 10- dicarboximido)propylamino]-2- [2- (3- nitronaphthalene-1, 8- dicarboximido)propylamino]ethane; (R,R)-1- [2- (3-nitro-7-methyl-5- azaphenanthrene- 1, 10-dicarboximido)propylamino]-2-[2-(3-nitro¬ naphthalene-l, 8-dicarboximido)-propylamino]ethane; (R,R)-1- [2-(6-azaphenanthrene-l, 10- dicarboximido)propylamino]-2- [2- (3- nitronaphthalene-1, 8- dicarboximido)propylamino] ethane;

(R,R)-1- [3-nitro-6-azaρhenanthrene-l, 10- dicarboximido)propylamino]-2- [2- (3-nitro-naphthalene-l, 8- dicarboximido)propylamino]ethane;

(R,R)-2-{2-[2-( (2-(l,3-dioxo-lH-benz[de] isoquinolin-2-

(3H)-yl)propylamino) ) ethylamino]-1-methylethyl}-5-nitro- lH-benz [de] isoquinolin-1, 3- (2H) -dione;

(S, S) -2-{2- [2- ( (2- (1, 3-dioxo-lH-benz [de]-isoquinolin-2- (3H)-yl)-propylamino) )ethylamino]-1-methylethyl}-5- nitro-lH-benz [de]isoquinolin-1,3- (2H)-dione; (R,S)-2-{2-[2-( (2- (1, 3-dioxo-lH-benz [de] -isoquinolin-2- (3H) -yl) -propylamino) ) ethylamino] -1-methylethyl}-5- nitro-lH-benz [de] isoquinolin-1, 3- (2H) -dione; and (S,R)-2-{2- [2- ( (2- (1, 3-dioxo-lH-benz [de]-isoquinolin-2- (3H)-yl)-propylamino) )ethylamino]-1-methylethyl}-5- nitro-lH-benz [de] isoquinolin-1,3- (2H) -dione.

22. A method according to Claim 20 wherein the unsymmetrical bis-imide product of Formula V is selected from the following:

(R,R)-1-[2-(acenaphthene-5, 6-dicarboximido) propylamino]-2- [2- (3-nitronaphthalene-l, 8-dicarboximido) propylamino]ethane;

(S,S)-1-[2- (acenaphthene-5, 6-dicarboximido) propylamino]-2- [2-(3-nitronaphthalene-l, 8-dicarboximido) propylamino]ethane; (R,S)-1-[2-(acenaphthene-5, 6-dicarboximido) propylamino]-2- [2-(3-nitronaphthalene-l, 8-dicarboximido) propylamino]ethane;

(S,R)-1- [2- (acenaphthene-5, 6-dicarboximido) propylamino]-2- [2- (3-nitronaphthalene-l, 8-dicarboximido) propylamino]ethane; (R,R)-1- [2- (3-nitro-6-azaphenanthrene-l, 10- dicarboximido)propylamino]-2- [2- (3-nitronapthalene-l,8- dicarboximido)propylamino]ethane.

23. A method of Claim 16 or 17 wherein the heating step (b) is carried out by flow of the reaction solution through a hollow tube, said tube having a heated segment which is maintained at a temperature effective to yield the bis-imide product of Formula V with a purity of greater than 80%. 24. A method of Claim 16 or 17 wherein the heating step (b) is carried out by flow of the reaction solution through a hollow tube, said tube having a heated segment which is maintained at a temperature effective to yield the bis-imide product of Formula V with a purity of greater than 95%.

25. A method of Claim 16, 17, or 23 further comprising the steps of: (c) adding the products of step (b) to water to precipitate a free base form of the compound of Formula V;

(d) isolating the free base form of the compound of Formula V; and

(e) acidifying the isolated free base of the compound of Formula V with a mineral acid or an organic acid to yield a pharmaceutically acceptable salt thereof.

26. The method of Claim 16, 17, or 23 further comprising the steps of: (c) adding the products of step (b) to a solution of a mineral acid or an organic acid in an organic solvent to yield a pharmaceutically acceptable salt of the compound of Formula V.

27. The method of Claim 25 wherein the acid is methanesulfonic acid.

28. The method of Claim 26 wherein the acid is methanesulfonic acid.

29. The method of Claim 9 wherein the heated segment of the tube is immersed in a heating bath maintained at a temperature of from about 80^*C to about 160"C.

30. The method of Claim 9 wherein the tube is a metal alloy tube. 31. The method of Claim 9 wherein the reaction flows through the tube at a flow rate of about 0.1 to about 500 mL/min.

32. The method of Claim 9 wherein the reaction is resident in the heated segment of the tube for about 0.1 minutes to about 1 hour.

33. The method of Claim 9 wherein the tube has an inside diameter of about 0.05 cm to about 3 cm and a wall thickness of about 0.02 cm to about 0.3 cm.