Camptothecin derivatives and process for their preparation

The present invention relates to new camptothecin derivatives of the formula (I) ##STR1## wherein B is a group B' or B" ##STR2## wherein each of (x) and (y) is a single or double bond. The present invention also provides processes for their preparation as well as pharmaceutical compositions containing the same.

The present invention relates to new camptothecin derivatives, to a process 
for their preparation, and to pharmaceutical compositions containing them. 
BACKGROUND OF THE INVENTION 
Camptothecin and some of its analogous compounds such as, for example, 
9-amino camptothecin, display potent antitumor activity by the inhibition 
of Topoisomerase I which is a monomeric enzyme involved in some important 
cellular functions and cellular growth (see, for instance, Wani et al., J. 
Med. Chem. 1987, 30, 1774; Hsiang et al., Cancer Res. 1989, 49, 4385 and 
Cancer Res. 1989, 49, 1465). 
Unfortunately, camptothecin and some of its derivatives such as the above 
mentioned 9-amino camptothecin, suffer of low solubility in aqueous 
solutions. This drawback makes very difficult their administration and the 
preparation of acceptable pharmaceutical formulations containing them 
(see, for instance, W. J. Slichenmyer et al., Journal of the National 
Cancer Institute, Vol. 85, No. 4, 1993, pp 271-291 and, in particular, 
page 275 for 9-amino camptothecin). 
Therefore, there is a need to find new camptothecin derivatives that, while 
maintaining or increasing biological activity of camptothecin are, in the 
same time, endowed with water solubility and/or chemicophysical 
characteristics which make these derivatives suitable for being included 
in pharmaceutically acceptable formulations. 
The compounds of this invention fulfill such a need. 
DESCRIPTION OF THE INVENTION 
Accordingly, the present invention relates to camptothecin derivatives of 
formula (I) 
##STR3## 
wherein B is a group B' or B" 
##STR4## 
wherein each of (x) and (y) is a single or double bond, 
R.sub.1 and R.sub.2 are each independently hydrogen, C.sub.1 -C.sub.6 
alkyl, C.sub.3 -C.sub.7 cycloalkyl, phenyl C.sub.1 -C.sub.6 alkyl or an 
unsubstituted or substituted phenyl ring, 
R.sub.3 and R.sub.4 are 
(a) each independently substituents having the same meaning of R.sub.1 and 
R.sub.2 or 
(b) combined together with the nitrogen atom to which they are linked to 
form a 3-7 membered saturated, unsubstituted or substituted 
heteromonocyclic ring, which may additionally contain another heteroatom 
selected from nitrogen, oxygen and sulphur, and 
A.sup.- is a pharmaceutically acceptable anion of a pharmaceutically 
acceptable inorganic or organic acid, provided that 
(i) when (x) is a double bond, (y) is a single bond and when (y) is a 
double bond, (x) is a single bond, and 
(ii) when B is a group B', then one of R.sub.2, R.sub.3 and R.sub.4 is 
absent; 
R.sub.6 is hydrogen or C.sub.1 -C.sub.6 alkyl; and 
X is hydrogen or C.sub.1 -C.sub.6 alkyl; and 
X is hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, C.sub.1 
-C.sub.6 acyloxy, C.sub.3 -C.sub.7 cycloalkyl, C.sub.3 -C.sub.7 
cycloalkoxy, benzoyloxy, amino, hydroxy, nitro, a halogen atom or a 
methylenedioxy group linked to the positions 10 and 11 of the molecule. 
The invention includes also the pharmaceutically acceptable salts of the 
compounds of formula (I). 
In the formulae of the present specification, a dotted line ( . . . ) 
indicates a substituent in the .alpha.-configuration, i.e. below the plane 
of the ring; a wedged line () indicates a substituent in the 
.beta.-configuration, i.e. above the plane of the ring. 
In this specification, the hydrocarbon chain of the alkyl, alkoxy and 
acyloxy groups may be a straight or a branched chain. 
Preferably, B is linked to the position 9 or 10 of the molecule. 
Preferably, C.sub.1 -C.sub.6 alkyl is methyl, ethyl, n-propyl, isopropyl, 
n-butyl, isobutyl, sec-butyl or t-butyl. 
Preferably, C.sub.3 -C.sub.7 cycloalkyl is cyclopropyl, cyclobutyl, 
cyclopentyl or cyclohexyl. 
Preferably, phenyl C.sub.1 -C.sub.6 alkyl is benzyl, phenyl-ethyl or 
phenyl-propyl. 
Preferably, C.sub.1 -C.sub.6 alkoxy is methoxy, ethoxy, n-propoxy, 
isopropoxy or n-butoxy. 
Preferably, C.sub.3 -C.sub.7 cycloalkoxy is cyclopropoxy, cyclobutoxy, 
cyclopentyloxy or cyclohexyloxy. 
Preferably, C.sub.1 -C.sub.6 acyloxy is acetoxy, propanoyloxy or 
butanoyloxy. 
A halogen atom is chlorine, bromine, fluorine or iodine, preferably 
chlorine or bromine. 
When one of R.sub.1, R.sub.2, R.sub.3 and R.sub.4 is an unsubstituted or 
substituted phenyl ring, it may be represented by a group 
##STR5## 
wherein Q is hydrogen, C.sub.1 -C.sub.6 alkyl, C.sub.1 -C.sub.6 alkoxy, 
C.sub.1 -C.sub.6 acyloxy or a halogen atom. 
Preferably, Q is hydrogen; C.sub.1 -C.sub.4 alkyl, in particular methyl, 
ethyl, n-propyl, isopropyl, n-butyl, isobutyl or sec-butyl; C.sub.1 
-C.sub.4 alkoxy, in particular methoxy, ethoxy or isopropoxy; or a halogen 
atom, in particular chlorine. Particularly preferred values of Q are 
hydrogen, methyl, ethyl, n-propyl, isopropyl, methoxy and chlorine. 
When R.sub.3 and R.sub.4 combined together with the nitrogen atom to which 
they are linked form a 3-7 membered saturated, substituted or 
unsubstituted heteromonocyclic ring, said ring may be represented by a 
group 
##STR6## 
wherein Y is --O--, --S--, --CH.sub.2 -- or &gt;NR.sub.5 wherein R.sub.5 is 
hydrogen, C.sub.1 -C.sub.6 alkyl, or a phenyl ring represented by the 
above group 
##STR7## 
wherein Q is as defined above; and m and n are each independently zero or 
an integer of 1 to 5, provided that, when one of m and n is zero, the 
other is not zero and that m+n is not greater than 5. 
Preferably, R.sub.5 is hydrogen or methyl. 
Preferably, R.sub.3 and R.sub.4 combined together with the nitrogen atom to 
which they are linked form aziridine, azetidine, pyrrolidine, piperidine, 
hexamethyleneimine, piperazine, methylpiperazine or morpholine, in 
particular pyrrolidine, piperidine, hexamethyleneimine, piperazine, 
methylpiperazine or morpholine. 
A.sup.- is a pharmaceutically acceptable anion of pharmaceutically 
acceptable acids, both inorganic acids such as, e.g., hydrochloric, 
sulfuric, phosphoric, diphosphoric, hydrobromic or nitric acid, and 
organic acids such as, e.g., citric, fumaric, maleic, malic, ascorbic, 
succinic, tartaric, benzoic, acetic, phenylacetic, methanesulfonic, 
ethanesulfonic, benzenesulfonic or p-toluenesulfonic acid. 
Preferably, A.sup.- is a halide, acetate, benzoate, methanesulfonate, or 
p-toluenesulfonate anion, in particular chloride, acetate, 
methanesulfonate or p-toluenesulfonate anion. 
Preferably, R.sub.6 is hydrogen, methyl or ethyl. 
Preferably, X is hydrogen, hydroxy, amino, nitro, a halogen atom, methoxy, 
acetoxy, propanoyloxy, benzoyloxy or 10,11 methylenedioxy, in particular 
hydrogen, hydroxy, methoxy or 10,11 methylenedioxy. 
As already said, the present invention includes camptothecin derivatives of 
formula (I) in the form of free bases and in the form of pharmaceutically 
acceptable salts with pharmaceutically acceptable acids both inorganic and 
organic acids. 
Preferred salts according to the invention are the salts with 
pharmaceutically acceptable acids, both inorganic such as, e.g., 
hydrochloric, sulfuric, phosphoric, diphosphoric, hydrobromic or nitric 
acid, and organic acids such as, e.g., citric, fumaric, maleic, malic, 
ascorbic, succinic, tartaric, benzoic, acetic, phenylacetic, 
methanesulfonic, ethanesulfonic, benzenesulfonic or p-toluenesulfonic 
acid. 
It is intended that also pharmaceutically acceptable quaternary ammonium 
salts, namely the compounds of formula (I) wherein B is a group B", are 
encompassed in the general definition "pharmaceutically acceptable salts" 
of the compounds of formula (I) of the present invention. 
A preferred class of compounds according to the invention are the compounds 
of formula (I), wherein B is a group B' or B" 
##STR8## 
wherein each of (x) and (y) is a single or double bond, 
R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently hydrogen, 
methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, 
cyclobutyl, cyclopentyl, cyclohexyl, benzyl, phenyl-ethyl or an 
unsubstituted or substituted phenyl ring represented by a group 
##STR9## 
wherein Q is hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, 
isobutyl, sec-butyl, methoxy, ethoxy, n-propoxy, isopropoxy, fluorine, 
chlorine or bromine, 
A.sup.- is a pharmaceutically acceptable anion of a pharmaceutically 
acceptable inorganic or organic acid selected from chloride, acetate, 
methanesulfonate and p-toluenesulfonate, provided that 
(i) when (x) is a double bond, (y) is a single bond and when (y) is a 
double bond, (x) is a single bond, and 
(ii) when B is a grop B', then one of R.sub.2, R.sub.3 and R.sub.4 is 
absent; 
R.sub.6 is hydrogen, methyl or ethyl; 
X is hydrogen, hydroxy, methoxy or a methylenedioxy group linked to the 
positions 10 and 11 of the molecule; 
and the pharmaceutically acceptable salts thereof. 
Another preferred class of compounds according to the invention are 
compounds of formula (I) wherein B is a group B' or B" 
##STR10## 
wherein each of (x) and (y) is a single or double bond, 
R.sub.l and R.sub.2 are each independently hydrogen, methyl, ethyl, 
n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl, t-butyl, cyclobutyl, 
cyclopentyl, cyclohexyl, benzyl, phenyl-ethyl, or an unsubstituted or 
substituted phenyl ring represented by a group 
##STR11## 
wherein Q is hydrogen, methyl, ethyl, n-propyl, isopropyl, n-butyl, 
isobutyl, sec-butyl, methoxy, ethoxy, n-propoxy, isopropoxy, fluorine, 
chlorine or bromine, 
R.sub.3 and R.sub.4 combined together with the nitrogen atom to which they 
are linked form pyrrolidine, piperidine, hexamethyleneimine, piperazine, 
methylpiperazine or morpholine, 
A.sup.- is a pharmaceutically acceptable anion of a pharmaceutically 
acceptable inorganic or organic acid, selected from chloride, acetate, 
methanesulfonate, and p-toluenesulfonate, provided that 
(i) when (x) is a double bond, (y) is a single bond and when (y) is a 
double bond, (x) is a single bond, and 
(ii) when B is a group B', then one of R.sub.2, R.sub.3 and R.sub.4 is 
absent; 
R.sub.6 is hydrogen, methyl or ethyl; 
X is hydrogen, hydroxy, methoxy or a methylenedioxy group linked to the 
positions 10 and 11 of the molecule, and the pharmaceutically acceptable 
salts thereof. 
Examples of specific compounds preferred under the invention are the 
following: 
(1) 9-(iminomethyl-amino)-camptothecin; 
(2) 9-(1-imino-ethylamino)-camptothecin; 
(3) 9-(methylimino-methylamino)-camptothecin; 
(4) 9-(dimethylamino-methyleneamino)-camptothecin; 
(5) 9-(dimethylamino-cyclohexyl-methyleneamino)-camptothecin; 
(6) 9-[(imino-phenyl-methyl)-amino]-camptothecin; 
(7) 9-(1-phenylimino-ethylamino)-camptothecin; 
(8) 9-(1-morpholin-4-yl-ethylideneamino)-camptothecin; 
(9) 10-(iminomethyl-amino)-camptothecin; 
(10) 10-(1-imino-ethylamino)-camptothecin; 
(11) 10-(methylimino-methylamino)-camptothecin; 
(12) 10-(dimethylamino-methyleneamino)-camptothecin; 
(13) 10-(dimethylamino-cyclohexyl-methyleneamino)-camptothecin; 
(14) 10-[(imino-phenyl-methyl)-amino]-camptothecin; 
(15) 10-(1-phenylimino-ethylamino)-camptothecin; 
(16) 10-(1-morpholin-4-yl-ethylideneamino)-camptothecin; 
(17) 10-hydroxy-9-(iminomethyl-amino)-camptothecin; 
(18) 10-hydroxy-9-(1-imino-ethylamino)-camptothecin; 
(19) 10-hydroxy-9-(1-dimethylamino-ethylideneamino)-camptothecin; 
(20) 11-hydroxy-9-(iminomethyl-amino)-camptothecin; 
(21) 11-hydroxy-9-[(imino-phenyl-methyl)-amino]-camptothecin; 
(22) 11-hydroxy-9-(1-phenylimino-ethylamino)-camptothecin; 
(23) 10-hydroxy-9-(1-morpholin-4-yl-ethylideneamino)-camptothecin; 
(24) 10,11-methylenedioxy-9-(iminomethyl-amino)-camptothecin; 
(25) 10,11-methylenedioxy-9-(1-imino-ethylamino)-camptothecin; 
(26) 10,11-methylenedioxy-9-[(methylimino-methyl)-amino]-camptothecin; 
(27) 10,11-methylenedioxy-9-(1-imino-propylamino)-camptothecin; 
(28) 10,11-methylenedioxy-9-(1-methylimino-ethylamino)-camptothecin; 
(29) 
10,11-methylenedioxy-9-[(ethyl-methyl-amino)-methyleneamino]-camptothecin; 
(30) 
10,11-methylenedioxy-9-[(cyclohexyl-methylimino-methyl)-amino]-camptotheci 
n; 
(31) 9-[1-(4-methyl-piperazin-1-yl)-methyleneamino]-camptothecin; 
(32) 10-methoxy-9-(iminomethyl-amino)-camptothecin; 
(33) 10-methoxy-9-(1-imino-ethylamino)-camptothecin; 
(34) 10-methoxy-9-(1-imino-pentylamino)-camptothecin; 
(35) 10-methoxy-9-{[imino-(4-methoxy-phenyl)-methyl]-amino}-camptothecin; 
(36) 10-methoxy-9-[(phenylimino-methyl)-amino]-camptothecin; 
(37) 10-methoxy-9-(dimethylamino-methyleneamino)-camptothecin; 
(38) 10-methoxy-9-(iminomethyl-methylamino)-camptothecin; 
(39) 9-(2-methyl-1-imino-propylamino)-camptothecin; 
(40) 10-methoxy-9-(2-methyl-1-methylimino-propylamino)-camptothecin; 
(41) 10-hydroxy-9-(2,2-dimethyl-1-imino-propylamino)-camptothecin; 
(42) 10-methoxy-9-(pyrrolidin-1-yl-methyleneamino)-camptothecin; 
(43) 10,11-methylenedioxy-9-[(tert-butylimino-methyl)-amino]-camptothecin; 
(44) 9-[(isopropylimino-methyl)-amino]-camptothecin; and 
(45) 7-ethyl-9-(iminomethyl-amino)-camptothecin, 
The structural formula of the above listed compounds is illustrated in the 
following Table 1, with reference to formula (I) 
##STR12## 
TABLE 1 
__________________________________________________________________________ 
Position 
COM- of 
POUND 
group B 
X R.sub.1 R.sub.2 
R.sub.3 
R.sub.4 
R.sub.6 
__________________________________________________________________________ 
(1) 9 H H H H -- H 
(2) 9 H CH.sub.3 H H -- H 
(3) 9 H H H CH.sub.3 
-- H 
(4) 9 H H -- CH.sub.3 
CH.sub.3 
H 
(5) 9 H Cy -- CH.sub.3 
CH.sub.3 
H 
(6) 9 H 
H H -- H 
(7) 9 H CH.sub.3 H 
##STR13## 
-- H 
(8) 9 H CH.sub.3 -- 
##STR14## H 
(9) 10 H H H H -- H 
(10) 10 H CH.sub.3 H H -- H 
(11) 10 H H H CH.sub.3 
-- H 
(12) 10 H H -- CH.sub.3 
CH.sub.3 
H 
(13) 10 H Cy -- CH.sub.3 
CH.sub.3 
H 
(14) 10 H 
##STR15## H H -- H 
(15) 10 H CH.sub.3 H 
##STR16## 
-- H 
(16) 10 H CH.sub.3 -- 
##STR17## H 
(17) 9 10-OH H H H -- H 
(18) 9 10-OH CH.sub.3 H H -- H 
(19) 9 10-OH CH.sub.3 -- CH.sub.3 
CH.sub.3 
H 
(20) 9 11-OH H H H -- H 
(21) 9 11-OH 
##STR18## H H -- H 
(22) 9 11-OH CH.sub.3 H 
##STR19## 
-- H 
(23) 9 10-OH H -- 
##STR20## H 
(24) 9 
##STR21## 
H H H -- H 
(25) 9 
##STR22## 
CH.sub.3 H H -- H 
(26) 9 
##STR23## 
H H CH.sub.3 
-- H 
(27) 9 
##STR24## 
Et H H -- H 
(28) 9 
##STR25## 
CH.sub.3 H CH.sub.3 
-- H 
(29) 9 
##STR26## 
H -- CH.sub.3 
Et H 
(30) 9 
##STR27## 
Cy H CH.sub.3 
-- H 
(31) 9 H H -- 
##STR28## H 
(32) 9 10-OCH.sub.3 
H H H -- H 
(33) 9 10-OCH.sub.3 
CH.sub.3 H H -- H 
(34) 9 10-OCH.sub.3 
n-Bu H H -- H 
(35) 9 10-OCH.sub.3 
##STR29## H H -- H 
(36) 9 10-OCH.sub.3 
H H 
##STR30## 
-- H 
(37) 9 10-OCH.sub.3 
H -- CH.sub.3 
CH.sub.3 
H 
(38) 9 10-OCH.sub.3 
H CH.sub.3 
H -- H 
(39) 9 H i-Pr H H -- H 
(40) 9 10-OCH.sub.3 
i-Pr H CH.sub.3 
-- H 
(41) 9 10-OH t-Bu H H -- H 
(42) 9 10-OCH.sub.3 
H -- 
##STR31## H 
(43) 9 
##STR32## 
H H t-Bu -- H 
(44) 9 H H H i-Pr -- H 
(45) 9 H H H H -- Et 
__________________________________________________________________________ 
In Table 1, the symbols Et, i-Pr, n-Bu, t-Bu and Cy stand respectively for 
ethyl, isopropyl, n-butyl, t-butyl and cyclohexyl. 
The compounds 1 to 45, listed on the above Table 1, may be also in the form 
of pharmaceutically acceptable salts. 
The compounds of the present invention may be prepared by a process which 
comprises: 
1) reacting a compound of formula (II) 
##STR33## 
wherein R.sub.2, R.sub.6 and X are as defined above, with a compound of 
formula (III) 
##STR34## 
wherein R.sub.1, R.sub.3 and R.sub.4 are as defined above, A.sup.-.sub.1 
is either a pharmaceutically acceptable anion A.sup.- as defined above or 
any other suitable anion, and Z is a leaving group, so obtaining a 
compound of formula (I) wherein R.sub.6 and X are as defined above, and 
wherein, according to the reaction conditions, B is a group B' or B" as 
defined above; and, if desired, 
2) converting a compound of formula (I) wherein R.sub.6 and X are as 
defined above, B is a group B" as defined above wherein one of R.sub.2, 
R.sub.3 and R.sub.4 is hydrogen, into a corresponding compound of formula 
(I) wherein R.sub.6 and X are as defined above and B is a group B' as 
defined above, and, if desired, 
3) salifying a compound of formula (I) wherein R.sub.6 and X are as defined 
above and B is a group B' as defined above, so obtaining a compound of 
formula (I) in the form of a pharmaceutically acceptable salt. 
The starting compounds of formula (II) have a 20(S)-configuration which is 
retained throughout the process leading to the compounds of formula (I). 
The compounds of formula (II) are typically free of the corresponding 
20(R)-isomers. 
However, said process may be applied to a racemic mixture of a compound of 
formula (II) and the corresponding 20(R)-isomer. In that case, a racemic 
mixture of a compound of formula (I) and a 20(R)-isomer of a compound of 
formula (I) is obtained. 
In the compounds of formula (III), the leaving group Z may be C.sub.1 
-C.sub.6 alkoxy, C.sub.3 -C.sub.7 cycloalkoxy, C.sub.1 -C.sub.6 acyloxy, 
benzoyloxy, C.sub.3 -C.sub.7 cycloacyloxy, a halogen atom, 
trifluoromethanesulfonyloxy, p-toluenesulfonyloxy or methanesulfonyloxy. 
Preferred meanings which Z may assume include methoxy, ethoxy, propoxy, 
isopropoxy, acetoxy, propanoyloxy, benzoyloxy, fluorine, chlorine, 
bromine, iodine, trifluoromethanesulfonyloxy, p-toluenesulfonyloxy or 
methanesulfonyloxy. 
Particularly preferred meanings which Z may assume include methoxy, ethoxy, 
propoxy, isopropoxy, acetoxy, propanoyloxy, benzoyloxy, chlorine, bromine, 
trifluoromethanesulfonyloxy, p-toluenesulfonyloxy or methanesulfonyloxy. 
In the compound of formula (III) A.sup.-.sub.1 is preferably a 
pharmaceutically acceptable anion A.sup.- as defined above. 
The reaction reported under the above item 1) may be performed reacting a 
compound of formula (II) dissolved in a suitable solvent with from a 
stoichiometric quantity to a large excess of a compound of formula (III), 
at a temperature of from about -20.degree. C. to about 100.degree. C., 
preferably from about 0.degree. C. to about 80.degree. C., for a time 
which may vary from about few minutes to several days such as from 5 
minutes to 3 days, preferably from about one hour to about one day, 
optionally in the presence of a suitable inorganic or organic base. 
When the reaction of item 1) is carried out in the absence of a suitable 
inorganic or organic base, a compound of formula (I) wherein R.sub.6 and X 
are defined above and wherein B is a group B" as defined above may be 
obtained. When the reaction of item 1) is carried out in the presence of a 
suitable inorganic or organic base, a compound of formula (I) wherein 
R.sub.6 and X are as defined above and wherein B is a group B' as defined 
above may be obtained. 
Suitable solvents include dimethylformamide (DMF), water, CH.sub.3 OH, 
acetic acid, CHCl.sub.3, dioxane, tetrahydrofuran (THF) and mixtures 
thereof. 
Suitable inorganic bases may be, for example, salts with alkali or alkaline 
earth metals, such as, for example, NaOH, NaHCO.sub.3, Na.sub.2 CO.sub.3 
or CaCO.sub.3. 
Suitable organic bases may be, for example, trialkylamines such as, e.g., 
triethylamine or diisopropylethylamine amine; or heteroaromatic bases such 
as, e.g., pyridine or 2,6-C.sub.1 -C.sub.6 alkyl substituted pyridines 
such as, e.g., 2,6-lutidine. 
The conversion reported under the above item 2) may be carried out 
following conventional procedures; for example, the conversion may be 
carried out in a suitable aqueous solvent by adding from a stoichiometric 
amount to a slight excess of an organic or inorganic base. 
The organic or inorganic base which can be used under item 2) may be, for 
example, selected among those optionally used under item 1). 
Conventional methods may be used in order to salify a compound of formula 
(I) as reported under item 3). 
In particular, a compound of formula (I) wherein B is a group B' or B" 
linked to the position 9 of the molecule wherein R.sub.1, R.sub.3, 
R.sub.4, (x), (y) and A.sup.- are as defined above and R.sub.2 is 
hydrogen, and wherein R.sub.6 is as defined above and X is 10- or 
12-hydroxy, may be prepared reacting in situ, a corresponding compound of 
formula (II) wherein R.sub.6 is as defined above, R.sub.2 is hydrogen and 
X is 10- or 12-hydroxy, with a compound of formula (III) as defined above, 
without isolating said compound of formula (II) from the reaction mixture 
in which it has been obtained, by reduction of a compound of formula (IV) 
##STR35## 
wherein R.sub.6 is as defined above and the hydroxy group is linked to the 
position 10 or 12 of the molecule. 
The reduction of the compound of formula (IV) may be carried out, for 
example, with suitable reducing agents, or by catalytic reduction with 
suitable catalysts, in the presence of suitable reducing agents. For 
example, it may be performed as described in: J. March, Advanced Organic 
Chemistry, Third Edition, 1103. For instance, the reduction may be 
performed with reducing agents such as, SnCl.sub.2, or other metals or 
metal salts, such as Zn or Fe and their salts, in a suitable solvent such 
as dilute aqueous HCl, dilute aqueous protic acids, water, ethanol, 
methanol, or mixtures thereof, at a temperature of from -20.degree. C. to 
60.degree. C., for a period of from few minutes to several days such as 
from 5 minutes to 3 days, for example from 4 hours to 24 hours; or by the 
use of catalytic amounts of metals which perform nitro group reduction, 
such as, palladium, platinum oxide, platinum, Pd L.sub.2 wherein L is 
acetate or a halogen atom, rhodium or ruthenium, in the presence of 
molecular hydrogen or hydrogen sources, such as triethylammonium formate, 
formic acid, tributyltin hydride, cyclohexadiene, polymethylhydrosiloxane, 
etc., in a suitable solvent, such as dimethylformamide (DMF), CH.sub.3 OH, 
acetic acid, CHCl.sub.3, dioxane, or mixtures thereof, at a temperature of 
from about 0.degree. C. to 100.degree. C., for a time of from 1 hour to 3 
days, and at a pressure of from 1 atm to 100 atm. 
The compounds of formula (II) and (III) are known compounds or may be 
obtained following known methods. 
The compounds of formula (IV) may be obtained, for example, reacting a 
10-hydroxy or 12-hydroxy camptothecin with suitable common nitrating 
agents such as, e.g., nitric acid, mixtures of nitric and sulphuric acid, 
or other nitrating agents such as, e.g., potassium nitrate or nitric acid 
and boron trifluoride such as boron trifluoride monohydrate (see for 
instance Olah, G. A. et al., Synthesis 1085, 1992), or nitric 
acid/trifluoromethanesulfonic anhydride (ibid., 1087, 1992), at a 
temperature of from -20.degree. C. to 100.degree. C., for a time of from a 
few minutes to several days such as from 5 minutes to 3 days, for example 
from 4 hours to 24 hours. 
The 10-hydroxy and 12-hydroxy camptothecins may be obtained, for example, 
by known methodologies from camptothecin (see for instance JP-A-59-51288; 
JP-A-59-51299; J. Med. Chem. 34, 98, 1991; and Chem. Pharm. Bull. 39, 
3183, 1991). 
In particular, 10-hydroxy-camptothecin is a natural product found in the 
same plant as camptothecin (see for instance Wani et al., J. Org. Chem., 
34, 1364, 1969). 
The compounds of formula (I) are water soluble by the virtue of the basic 
side chain represented by the basic group B which may form salts with 
pharmaceutically acceptable inorganic or organic acids. The solubility of 
the compounds of formula (I) in water is especially important since it 
permits the administration of these compounds in aqueous pharmaceutical 
compositions. 
The compounds of the present invention are endowed with antitumor activity, 
for example they are effective against leukemia and solid tumors such as, 
for example, colon and rectal tumors. 
The antitumor activity of the compounds of the present invention was shown, 
for example, by the fact that they have been found to possess both "in 
vitro" cytotoxic activity and "in vivo" antileukemic activity. 
As an example, the activity of 9-(iminomethyl-amino)camptothecin (internal 
code FCE 28536) and 9-(dimethylamino-methyleneamino)-camptothecin 
(internal code FCE 29006) were tested according to the following methods 
(a) and (b). 
Method (a): Evaluation of Cytotoxic Activity 
L1210 murine leukemia cells were grown in vitro as a stationary suspension 
in RPMI 1640 medium supplemented with 10% fetal calf serum, 2 mM 
L-glutamine, 10 .mu.M B-mercaptoethanol, 100 UI/ml penicillin and 100 
.mu.g streptomycin. For assaying the cytotoxic activity, exponentialily 
growing cells were seeded at the concentration of 1.times.105 cells/ml and 
exposed to graded doses of the compounds under evaluation for 48 h at 
37.degree. C. in an humidified atmosphere of 5% CO.sub.2. The number of 
surviving cells was determined with a Coulter Counter; results are 
expressed as IC50 (dose causing 50% inhibition of cell growth in treated 
cultures relative to untreated controls after 48 h treatment). 
In this assay, 9-(iminomethyl-amino)-camptothecin (internal code FCE 28536) 
and 9-(dimethylamino-methyleneamino)-camptothecin (internal code FCE 
29006) were tested and the obtained results, which represent the mean of 3 
different experiments, are reported on Table 2 below. 
TABLE 2 
______________________________________ 
COMPOUND IC.sub.50 (nM) 
______________________________________ 
FCE 28536 82 
FCE 29006 120 
______________________________________ 
Method (b): Evaluation of Antitumor Activity 
L1210 murine leukemia was maintained in DBA2 mice by weekly ip transplants 
of 105 cells/mouse. For assaying the antileukemic activity, 105 
cells/mouse were implanted ip into CD2F1 mice; graded doses of the 
compounds under evaluation were administered ip 24 h after tumor cells 
implant on day 1 controls receiving vehicle alone. 
The activity of the drugs was determined evaluating the median survival 
time (MST) of each group of mice. 
The obtained results, expressed as % T/C, are reported on Table 3 below. 
TABLE 3 
______________________________________ 
DOSE 
COMPOUND (mg/kg) % T/C 
______________________________________ 
28536 5 150-163 
10 188 
15 219-213 
29006 5 150 
10 163 
15 175 
______________________________________ 
% TC = MST treated mice/MST contol mice .times. 100 
A human or animal body may thus be treated by a method which comprises the 
administration thereto of a pharmaceutically effective amount of a 
compound of formula (I) or salt thereof. 
The condition of the human or animal can thereby be improved. 
The compounds of the invention can be administered in a variety of dosage 
forms, e.g. orally, in the form of tablets, capsules, lozengers, liquid 
solutions or suspensions; rectally, in the form of suppositories; 
parenterally, e.g. intramuscularly, intravenously, intradermally or 
subcutaneously; or topically. 
The dosage depends upon, for example, the camptothecin derivative employed, 
the potency of the camptothecin derivative, the age, weight, condition of 
the patient and administration route; specific dosage regimens may be fit 
to any particular subject on the basis of the individual need and the 
professional judgement of the person administering or supervising the 
administration of the aforesaid compounds. For example, the dosage adopted 
for the administration to adult humans may range from 0.1 to 60 mg of 
camptothecin derivative per kg of body weight; a particularly preferred 
range may be from 1 to 40 mg of camptothecin derivative per kg of body 
weight. 
The dosages may be administered at once or may be divided into a number of 
smaller doses to be administered at varying intervals of time. 
Pharmaceutical compositions containing as an active ingredient a compound 
of formula (I) or a pharmaceutically acceptable salt thereof in 
association with a pharmaceutically acceptable carrier and/or diluent are 
also within the scope of the present invention. 
These pharmaceutical compositions contain an amount of active ingredient 
which is therapeutically effective to display antileukemic and/or 
antitumor activity. 
There may also be included as a part of the pharmaceutical compositions 
according to the invention, pharmaceutically acceptable binding agents 
and/or adjuvant materials. The active ingredients may also be mixed with 
other active principles which do not impair the desired action and/or 
supplement the desired action. The pharmaceutical compositions containing 
the compounds of the invention are usually prepared following conventional 
methods and may be administered in a pharmaceutically suitable form. 
For example, the solid oral forms may contain, together with the active 
compound, diluents, e.g. lactose, dextrose, saccharose, cellulose, corn 
starch or potato starch; lubricants, e.g. silica, talc, stearic acid, 
magnesium or calcium stearate, and/or polyethylene glycols; binding 
agents, e.g. starches, arabic gums, gelatin, methylcellulose, 
microcrystalline cellulose, carboxymethylcellulose or polyvinyl 
pyrrolidone; diaggregating agents, e.g. a starch, alginic acid, alginates 
or sodium starch glycolate; effervescing mixtures; dyestuffs; sweetening 
agents, e.g. sucrose or saccharin; flavouring agents, e.g. peppermint, 
methylsalicylate or orange flavouring; wetting agents, such as lecithin, 
polysorbates, laurylsulphates; and, in general, non-toxic and 
pharmacologically inactive substances used in pharmaceutical formulations. 
When the dosage unit form is a capsule, it may contain, in addition to 
material of the above type, a liquid carrier such as, e.g., a fatty oil. 
Said pharmaceutical preparations may be manufactured in known manner, for 
example, by means of mixing, granulating, tabletting, sugar-coating or 
film-coating processes. The liquid dispersions for oral administration may 
be, e.g. syrups, emulsions and suspensions. The syrups may contain as 
carrier, for example, saccharose or saccharose with glycerine and/or 
mannitol and/or sorbitol; in particular, a syrup to be administered to 
diabetic patients can contain as carriers only products not metabolizable 
to glucose, or metabolizable in very small amount to glucose, for example 
sorbitol. 
The suspensions and the emulsions may contain as carrier, for example, a 
natural gum, agar, sodium alginate, pectin, methylcellulose, 
carboxymethylcellulose, or polyvinyl alcohol. 
The suspensions or solutions for intramuscular injections may contain, 
together with the active compound, a pharmaceutically acceptable carrier, 
e.g. sterile water, olive oil, ethyl oleate, glycols, e.g. propylene 
glycol, and, if desired, a suitable amount of lidocaine hydrochloride. 
The solutions for intravenous injections or infusions may contain as 
carrier, for example, sterile water, or preferably they may be in the form 
of sterile, aqueous, isotonic saline solutions. 
The solutions or suspensions for parenteral therapeutic administration may 
also contain antibacterial agents, such as benzyl alcohol or methyl 
parabens; antioxidants, such as ascorbic acid or sodium bisulphite; 
chelating agents, such as ethylenediaminetetraacetic acid; buffers, such 
as acetates, citrates or phosphates and agents for the adjustment of 
tonicity, such as sodium chloride or dextrose. The parenteral preparation 
can be enclosed in ampoules, disposable syringes or multiple dose vials 
made of glass or plastic. 
The suppositories may contain together with the active compound a 
pharmaceutically acceptable carrier, e.g., coca-butter, polyethylene 
glycol, a polyoxyethylene sorbitan fatty acid ester surfactant or 
lecithin. 
Compositions for topical application, such as, e.g., creams, lotions or 
pastes, may be, e.g., prepared by admixing the active ingredient with a 
conventional oleaginous or emulsifying excipient. 
The following examples illustrate but do not limit the invention.

The number into bracket reported after the chemical name of the compounds 
prepared according to the following examples corresponds to the number 
given to the preferred compounds listed on pages 11, 12 and 13 of the 
present specification. 
EXAMPLE 1 
9-(iminomethyl-amino)-camptothecin (1) 
To a stirred solution of 9-amino camptothecin (0.5 g) in DMF (100 ml), 
ethyl formimidate hydrochloride (2.5 g) was added at room temperature, and 
the resulting mixture was stirred overnight. The solid was filtered off 
and the filtrate was evaporated in vacuo. The residue was taken-up with 
water and the pH of the resulting solution was adjusted to about 6.5. The 
precipitated solid was collected by filtration, carefully washed with 
small portions of cold water, and then dried to yield the title product 
(0.25 g). 
.sup.1 NMR (DMSO-d.sub.6), .delta.ppm: 0.87 (3H, t, J=7.3 Hz); 1.85 (2H, 
m); 5.27 (2H, s); 5.41 (2H, s); 6.50 (1H, broad signal); 7.04 (1H, d, 
J=7.3 Hz); 7.10 (2H, broad signal); 7.31 (1H, s); 7.67 (1H, dd, J=7.3, 8.5 
Hz); 7.73 (1H, d, J=8.5 Hz); 7.79 (1H, m); 8.94 (1H, s). MS (FD): 390. 
The title product (0.1 g) was suspended in water (2 ml) and 1N HCl (0.3 ml) 
was added. The resulting yellow solution was then freeze dries to yield 
the hydrochloride salt of the title product. 
Following analogous procedure the below listed compounds and their 
hydrochloride salts can be prepared: 
10,11-methylenedioxy-9-(iminomethyl-amino)-camptothecin (24); 
10-methoxy-9-(iminomethyl-amino)-camptothecin (32); 
10-(iminomethyl-amino)-camptothecin (9); 
11-hydroxy-9-(iminomethyl-amino)-camptothecin (20); and 
7-ethyl-9-(iminomethyl-amino)-camptothecin (45). 
EXAMPLE 2 
10-hydroxy-9-(iminomethyl-amino)-camptothecin (17) 
A solution of 10-hydroxy-9-nitro camptothecin (0.5 g) in DMF (100 ml) was 
hydrogenated at atmospheric pressure and room temperature in the presence 
of 10% Pd/C (0.05 g) until H.sub.2 consumption ceased. The resulting 
solution was filtered and then treated with ethyl formimidate 
hydrochloride (1.5 g). The solution was stirred overnight and worked-up as 
described in Example 1, to yield the title compound (0.1 g). 
EXAMPLE 3 
9-(1-imino-ethylamino)-camptothecin (2) 
To a stirred solution of 9-amino camptothecin (0.5 g) in DMF (100 ml), 
ethyl acetamidate hydrochloride (2.5 g) was added and the resulting 
mixture was stirred at 80.degree. C. overnight and worked-up as described 
in Example 1, to yield the title compound (0.2 g). 
Following analogous procedure the below listed compounds and their 
hydrochloride salts can be prepared: 
10,11-methylenedioxyoxy-9-(1-imino-ethylamino)-camptothecin (25); 
10-methoxy-9-(1-imino-methylamino)-camptothecin (38); 
10-methoxy-9-(1-imino-ethylamino)-camptothecin (33); 
10-(1-imino-ethylamino)-camptothecin (10); 
9-[(imino-phenyl-methyl)-amino]-camptothecin (6); 
10-[(imino-phenyl-methyl)-amino]-camPtothetin (14); 
11-hydroxy-9-[(imino-phenyl-methyl)-amino]-camptothecin (21); 
10, 11-methylenedioxy-9-(1-imino-propylamino)-camptothecin (27); 
10-methoxy-9-(1-imino-pentylamino)-camptothecin (34); 
10-methoxy-9-{[imino-(4-methoxy-phenyl)-methyl]-amino}-camptothecin (35); 
and 
9-(2-methyl-1-imino-propylamino)-camptothecin (39). 
EXAMPLE 4 
10-hydroxy-9-(1-imino-ethylamino)-camptothecin (18) 
A solution of 10-hydroxy-9-nitro camptothecin (0.5 g) in DMF (100 ml) was 
hydrogenated at atmospheric pressure and room temperature in the presence 
of 10% Pd/C (0.1 g) until H.sub.2 consumption ceased. The resulting 
solution was treated with ethyl acetamidate hydrochloride (2.0 g), and 
left at room temperature overnight. The solution was worked-up as 
described in previous examples, to yield the title compound (0.2 g). 
Following analogous procedure the below listed compounds can be obtained: 
10-hydroxy-9-(2,2-dimethyl-1-imino-propylamino)camptothecin (41); 
10-hydroxy-9-(1-dimethylamino-ethylideneamino)-camptothecin (19); and 
10-hydroxy-9-(1-morpholin-4-yl-ethylideneamino)-camptothecin (23). 
EXAMPLE 5 
By analogy with the previous Example 1 by using the appropriate imidate, 
the following compounds can be prepared: 
9-(methylimino-methylamino)-camptothecin (3); 
9-(dimethylamino-methyleneamino)-camptothecin (4); 
9-(dimethylamino-cyclohexyl-methyleneamino)-camptothecin (5); 
9-(1-phenylimino-ethylamino)-camptothecin (7); 
10-(1-morpholin-4-yl-ethylideneamino)-camptothecin (8); 
10-(methylimino-methylamino)-camptothecin (11); 
10-(dimethylamino-methyleneamino)-camptothecin (12); 
10-(dimethylamino-cyclohexyl-methyleneamino) camptothecin (13); 
10-(1-phenylimino-ethylamino)-camptothecin (15); 
10-(1-morpholin-4-yl-ethylideneamino)-camptothecin (16); 
11-hydroxy-9-(1-phenylimino-ethylamino)-camptothecin (22); 
10,11-methylenedioxy-9-[(methylimino-methyl)-amino]-camptothecin (26); 
10,11-methylenedioxy-9-(1-methylimino-ethylamino)-camptothecin (28); 
10,11-methylenedioxy-9-[(ethyl-methyl-amino)-methyleneamino]-camptothecin 
(29); 
10,11-methylenedioxy-9-[(cyclohexyl-methylimino-methyl)amino]-camptothecin 
(30); 
9-[1-(4-methyl-piperazin-1-yl)-methyleneamino]-camptothecin (31); 
10-methoxy-9-[(phenylimino-methyl)-amino]-camptothecin (36); 
10-methoxy-9-(dimethylamino-methyleneamino)-camptothecin (37); 
10-methoxy-9-(2-methyl-1-methylimino-propylamino)-camptothecin (40); 
10-methoxy-9-(pyrrolidin-1-yl-methyleneamino)-camptothecin (42); 
10,11-methylenedioxy-9-[(tert-butylimino-methyl)-amino]-camptothecin (43); 
and 
9-[(isopropylimino-methyl)-amino]-camptothecin (44). 
EXAMPLE 6 
9-(dimethylamino-methyleneamino)-camptothecin (4) 
Oxalyl chloride (1.15 ml) in ehter (5 ml) was added at -40.degree. C. to a 
stirred solution of dimethylformamide (1 ml) in ether (50 ml). 
The mixture was then stirred at room temperature for three hours. The 
precipitate was filtered, washed with ether, and added at room temperature 
to a solution of 9-amino camptothecin (150 mg) in DMF (20 ml). 
The mixture was stirred at room temperature overnight. 
The reaction mixture was then evaporated "in vacuo", and the residue was 
taken up with water. The aqueous solution was then washed twice with 
CH.sub.2 Cl.sub.2 and the organic layer was discharged. The pH of the 
aqueous layer was then adjusted by addition of NaHCO.sub.3, till complete 
precipitation of a yellow-brown solid was observed. The solid was 
collected by filtration and carefully washed with water. The crude product 
was then purified with reverse phase chromatography eluting with 
acidic-water/acetone mixtures. The appropriate fractions were collected, 
and freeze dried. 
The residue was taken-up with water (3 ml), and NaHCO.sub.3 was added until 
a complete precipitation was observed. 
The precipitate was collected by filtration, carefully washed with water, 
and dried, to yield the title product (90 mg). 
NMR (DMSO-d.sub.6) .delta.(ppm): 0.87 (3H, T, J=7.3 Hz); 1.85 (2H, m); 3.10 
(6H, s); 5.27 (2H, s); 5.41 (2H, s); 6.50 (1H, s); 7.08 (1H, m); 7.31 (1H, 
s); 7.68 (2H, m); 7.94 (1H, s); 9.04 (1H, s). 
MS (FD): 418 
The above precipitate (80 mg) was suspended again in water (2 ml) and 1N 
HCl (0.2 ml) was added. The solution was then freeze-dried to afford the 
title product as hydrochloride salt. 
EXAMPLE 7 
9-(1-imino-ethylamino)-camptothecin (2) 
The reaction was performed as described in Example 3, but using 
dimethylacetamide. 
After usual work-up there were obtained 0.1 g of the title product.