Compounds and complexes useful in medical imaging

The subject of the present invention is compounds which correspond to the following general formula: ##STR1## in which R.sub.1 and R.sub.3 independently of one another represent H, an alkyl, alkenyl, cycloalkyl, aryl, arylalkyl or an alkylaryl group, a heterocycle, or groups which are unsubstituted or substituted, in particular by one or more hydroxyl or alkoxy groups or halogen; PA0 n represents an integer from 1 to 5; PA0 i in each case takes values from 1 to n for the n successive ##STR2## links; R.sub.2, R.sub.4.sup.i and R.sub.5.sup.i independently of one another represent H, an alkyl, alkenyl, aryl, alkoxy, hydroxyalkyl, alkoxyalkyl, amido, acyl or carboxyalkyl group, or a salt, or an alkyl ester of the latter; or R.sub.4.sup.i and R.sub.5.sup.i together form an oxo group ##STR3## R.sub.6 and R.sub.7 represent H, or R.sub.6 and R.sub.7 together form an oxo group ##STR4## x represents a 5- or 6-membered heterocycle which contains at least one nitrogen atom, or, in the event that ##STR5## where R.sub.8 and R.sub.9 independently represent H, alkyl, aryl or arylalkyl, and R.sub.10 represents H, alkyl, aryl or arylalkyl. The present invention likewise relates to coordination complexes between these ligands and a metal as well as to kits containing these ligands and to reagents which permit the formation of a coordination complex between the ligand and the metals. More particularly, the present invention relates to complexes between these ligands and technetium .sup.99m Tc, which complexes can be used as diagnostic agents for brain imaging, heart imaging and blood imaging.

The present patent application relates to ligands capable of complexing 
metals. When those metals are radioactive, these complexes are useful in 
particular in medical imaging or in targeted radiotherapy, depending on 
the nature of the radioisotope. 
The present invention likewise relates to kits containing said ligands, 
said metals and reagents which make it possible to obtain the formation of 
a coordination complex between the ligands and the metals. 
More particularly, the present invention relates to complexes between these 
ligands and technetium .sup.99m Tc which can be used as diagnostic agents, 
in particular for brain imaging, heart imaging and blood imaging. 
The requirements which an agent for brain imaging must meet are firstly its 
ability to cross the blood/brain barrier, to settle and to accumulate in 
large concentrations in a relatively short time in the brain and to stay 
there during the period necessary for carrying out the analysis. This 
makes it necessary for the complex to undergo chemical or biochemical 
in-vivo modifications. For example, a pH displacement mechanism has been 
suggested, which takes into account the pH difference between the blood 
and the intracellular medium. Thus, if an amine has a pKa value similar to 
the PH of the brain, the neutral amine complex will be protonated once it 
is inside the brain. The complex which has been charged in this manner is 
trapped in the brain to such an extent that it is not capable of escaping 
by a reverse mechanism in view of the pKa of the amine. Likewise, this 
complex can undergo a chemical modification. This is the case with HM-PAO, 
where the lipophilic complex is transformed over time into a more 
hydrophilic complex which does not penetrate into the brain. The exact 
nature of this second complex and the mechanism at work have hitherto not 
been elucidated. It is also possible that the enzymatic hydrolysis of an 
active group takes place as is observed in "N,N'-1,2-ethylenediyl-L 
bis-L-cysteine diethyl ester" (.sup.99m Tc ECD), where the ester is 
hydrolyzed to give the L,L stereoisomer and not its D,D isomer, as a 
result of which the retention time in the brain is different for the two 
isomers, with a half-life of more than 1 440 minutes for the former and 
less than 30 minutes for the latter. 
Whatever the mechanism at work may be, an ideal complex in the context of 
brain imaging must have a good in-vitro stability, must be fixed rapidly 
in the brain, and must have a weak in-vivo stability, that is to say, an 
ability of in-vivo modification or transformation. 
In contrast to the established teaching with regard to agents for heart 
imaging, it seems that these need not necessarily consist of a cationic 
complex, but it is more likely that the decisive factor is their 
lipophilic property. 
The lipophilicity of complexes imparts to them the ability to label blood 
cells such as macrophages and thus to permit the detection of inflammation 
and of infections. 
The radioactive isotope of choice for medical imaging is .sup.99m Tc. At 
present, "cold kits" which can be .sup.99m Tc-labeled are not yet 
commercially available (MIBI: heart imaging) or have certain disadvantages 
(HMPAO: brain imaging, inflammatory site imaging) in the applications of 
brain imaging, heart imaging and inflammatory site imaging. .sup.99m Tc is 
generally available in the form of pertechnetate (TcO.sup.--.sub.4). The 
cold kits are composed of a lyophilized composition of non-radioactive 
components which, after reconstitution by means of a pertechnetate 
.sup.99m TcO.sup.--.sub.4 solution, gives the desired complex. Ideally, 
the stability of the complex after reconstitution must be sufficiently 
high such that the kit can be utilized over several hours. One problem 
frequently encountered in the present complexes is that the .sup.99m Tc 
complex does not guarantee a sufficiently high stability over time. 
Moreover, the ligands proposed to date usually have complicated chemical 
structures which entail costly preparation methods. 
With the aim of proposing multi-purpose use diagnostic agents which permit 
imaging, in particular of the brain, the heart and blood cells such as the 
macrophages, novel lipophilic and neutral ligands have been sought 
according to the present invention, which ligands have the best 
specifications required to this end and which overcome the abovementioned 
disadvantages. 
In effect, the subject of the present invention is novel compounds which 
correspond to the following general formula: 
##STR6## 
in which 
R.sub.1 and R.sub.3 independently of one another represent H, an alkyl, 
alkenyl, cycloalkyl, aryl, arylalkyl or an alkylaryl group, a heterocycle, 
or groups which are unsubstituted or substituted, in particular by one or 
more hydroxyl or alkoxy groups, or halogen, 
n represents an integer from 1 to 5, 
i in each case takes values from 1 to n for the n successive 
##STR7## 
links, 
R.sub.2, R.sub.4.sup.i and R.sub.5.sup.i independently of one another 
represent H, an alkyl, alkenyl, aryl, alkoxy, hydroxyalkyl, alkoxyalkyl, 
amido, acyl or carboxyalkyl group, or a salt, or an alkyl ester of the 
latter, or R.sub.4.sup.i and R.sub.5.sup.i together form an oxo group 
##STR8## 
R.sub.6 and R.sub.7 represent H, or R.sub.6 and R.sub.7 together form an 
oxo group 
##STR9## 
X represents a 5- or 6-ring membered heterocycle which contains at least 
one nitrogen atom, or, in the event that 
##STR10## 
where R.sub.8 and R.sub.9 independently represent H, alkyl, aryl or 
arylalkyl, and R.sub.10 represents H, alkyl, aryl or arylalkyl. 
Acyl, alkyl, hydroxyalkyl, carboxyalkyl, alkoxyalkyl and alkoxy in the 
present application are understood as meaning straight or branched chains 
having preferably 1 to 10 carbon atoms. 
The term alkenyl likewise denotes straight or branched chains, preferably 
those having 2 to 10 carbon atoms. 
The term aryl denotes the phenyl or substituted phenyl group. 
The terms cycloalkyl or cycloalkenyl denote rings having 5, 6 or 7 carbon 
atoms. 
A 5- or 6-membered heterocycle containing at least one nitrogen atom is 
understood as meaning one of the compounds represented by the formula II 
or one of its dehydro derivatives: 
##STR11## 
in which 
m is 0 or 1 and 
A is O, N--R.sub.11 or CH--R.sub.11 where R.sub.11 represents H, or alkyl 
or aryl which are substituted or unsubstituted. 
Examples of such heterocycles are aromatic groups, such as a pyrrolyl, 
imidazolyl, oxazolyl, pyrazolyl, pyridinyl or pyrimidinyl group. 
They can be bonded to the ligand of the formula I by an unsaturated carbon 
adjacent to N or A. 
Compounds of the formula 1 according to the invention which may be 
mentioned more particularly are the compounds for which n 2 or 3, and also 
those for which 
##STR12## 
In particular, compounds where R.sub.IO is trityl may be mentioned. 
Compounds which will be mentioned more particularly are those for which, in 
a general manner, R.sub.4.sup.i =R.sub.5.sup.i =H where i=1 to n, or those 
where R.sub.4.sup.i =R.sub.5.sup.i =H if i=1 to n-1, and 
##STR13## 
Finally, the compounds for which R.sub.1 and R.sub.3 independently of one 
another represent H, CH.sub.3, CF.sub.3, C(CH.sub.3).sub.3 or C.sub.2 
H.sub.5, may be mentioned. 
Some compounds according to the invention correspond to the formula III: 
##STR14## 
in which R.sub.1, R.sub.2, R.sub.3, R.sub.4.sup.i and R.sub.5.sup.i have 
the meanings given above. 
Ligands of the formula III which may be mentioned in particular are those 
for which R.sub.4.sup.i =R.sub.5.sup.i =H. 
Examples of the ligands of the formula III which are particularly 
interesting are the compounds where 
1) R.sub.1, R.sub.3 =CH.sub.3 or C.sub.2 H.sub.5, n=2 and R.sub.2 
=R.sub.4.sup.1 =R.sub.4.sup.2 =R.sub.5.sup.1 =R.sub.5.sup.2 =H; 
2) R.sub.1 =CH.sub.3, R.sub.3 =CF.sub.3, n=2 and R.sub.2 =R.sub.4.sup.1 
=R.sub.4.sup.2 =R.sub.5.sup.1 =R.sub.5.sup.2 =H, 
3) R.sub.1 =CF.sub.3, R.sub.3 =CH.sub.3, n=1 and R.sub.2 =R.sub.4.sup.1 
=R.sub.4.sup.2 =R.sub.5.sup.1 =R.sub.5.sup.2 =H 
4) R.sub.1 =R.sub.3 =C(CH.sub.3).sub.3, n=2 and R.sub.2 =R.sub.4.sup.1 
=R.sub.4.sup.2 =R.sub.5.sup.1 =R.sub.5.sup.2 =H; 
5) R.sub.1 =R.sub.2 =R.sub.3 =CH.sub.3 and n=2, R.sub.4.sup.1 
=R.sub.4.sup.2 =R.sub.5.sup.1 =R.sub.5.sup.2 =H, 
6) R.sub.1 =R.sub.3 =CH.sub.3, n=3 and R.sub.2 =R.sub.4.sup.1 
=R.sub.4.sup.2 =R.sub.4.sup.3 =R.sub.5.sup.1 =R.sub.5.sup.2 =R.sub.5.sup.3 
=H. 
Other compounds according to the invention correspond to the formula IV: 
##STR15## 
in which R.sub.1, R.sub.2, R.sub.3, R.sub.4.sup.i and R.sub.5.sup.i have 
the meanings given above in the general formula I. 
The compound of the formula IV which is especially interesting is that 
where n=2 and R.sub.2 =R.sub.4.sup.i =R.sub.5.sup.i =H. 
Among the latter, the example where n=2, R.sub.1 =R.sub.3 =CH.sub.3 and 
R.sub.2 =H is given. 
Other compounds according to the invention correspond to the formula V: 
##STR16## 
in which R.sub.1, R.sub.2, R.sub.3, R.sub.4.sup.i, R.sub.5.sup.i and 
SR.sub.10 have the meanings given above in the case of the definition of 
the general formula I. 
More particularly, the compounds of the formula V where R.sub.10 =trityl, 
n=2 or 3 and R.sub.4.sup.i =R.sub.5.sup.i =H may be mentioned. 
Among the latter, one example where R.sub.1 =R.sub.3 =CH.sub.3 and R.sub.2 
=H is given. 
Other compounds according to the invention correspond to the general 
formula VI 
##STR17## 
in which R.sub.1 to R.sub.7 have the meanings given above. 
Amongst the compounds of the formula VI, those for which R.sub.6 =R.sub.7 
=H and X represents a heterocycle may be mentioned. Those for which 
R.sub.4.sup.i =R.sub.5.sup.i =H will also be mentioned. 
The compounds of the formula VI in which n=2, R.sub.2 =R.sub.4.sup.i 
=R.sub.5.sup.i =R.sub.6 =R.sub.7 =H, R.sub.1 =R.sub.3 =CH.sub.3 or Et, and 
X is a pyrrolyl group, are mentioned as examples. 
A further subject of the present invention is a process for the preparation 
of the compounds according to the invention. 
In effect, these compounds can be prepared by reacting a heterocycle X 
which is substituted by a formyl group, of the formula 
##STR18## 
with an amine functional group of a diaminoalkylene of the formula 
NH.sub.2 --(CR.sub.4.sup.i R.sub.5.sup.i).sub.n --NH.sub.2 in acetonitrile 
in the presence of NaBH.sub.4. 
However, when X is 
##STR19## 
the ester functional group of a thioacetate, in particular ethyl 
thioacetate, of the formula EtO--OC--CR.sub.8 R.sub.9 --SH is reacted with 
the NH.sub.2 functional group of the diaminoalkylene NH.sub.2 
--[C(R.sub.4.sup.i R.sub.5.sup.i)].sub.n --NH.sub.2, in EtOH in the 
presence of N.sub.2, and, if desired, the SH functional group is then 
obtained in the form of the SR.sub.10 derivative by means of an alcohol 
R.sub.10 OH. 
Finally, when 
##STR20## 
an amine of the formula X(CR.sub.6 R.sub.7) NH.sub.2 is reacted with the 
amino acid HOOC(CR.sub.4.sup.i R.sub.5.sup.i).sub.n--1 --NH.sub.2 by 
activating the acid functional group with an activating group customary in 
peptide chemistry and by protecting the NH.sub.2 functional group by a 
likewise customary protective group. 
In all cases, the result is a compound of the formula VII 
##STR21## 
The resulting product, of the formula VII, is subsequently reacted with a 
dione of the formula VIII: 
##STR22## 
to obtain the compound of the formula (I) according to the invention. 
The compounds described in the invention are useful as ligands which can 
form complexes with metals. When these complexes are injected in vivo, 
they can display an affinity for cerebral or myocardial cells. Likewise, 
they can be used for labeling white corpuscles, and the labeled white 
corpuscles can be injected in vivo for detecting inflammatory sites. 
Depending on the isotope used for labelling, the compounds can be used as 
imaging agents or as piloting agents in targeted radiotherapy. 
The compounds according to the invention can occur in all forms and can be 
acidic or basic. 
The compounds described in the invention can be used either directly or 
coupled to a carrier protein such as a monoclonal antibody. Their role is 
then reduced to coupling a metal to the protein. 
A further subject of the present invention is therefore coordination 
complexes of a compound described in the invention with a radioactive or 
paramagnetic metal ion. 
The following radioisotopes may be mentioned in particular: .sup.111 In, 
.sup.113m In, .sup.67 Ga, .sup.68 Ga, .sup.157 Gd, .sup.201 Ti, .sup.117m 
Sn, .sup.64 Cu, .sup.186 Re, .sup.188 Re, .sup.90 Y, .sup.212 Bi, .sup.99 
Tc, .sup.99m Tc, .sup.97 Ru, .sup.51 Cr, .sup.57 Co, .sup.191 Os. 
The compounds according to the invention may be labeled by a radioactive 
halogen isotope which is a substituent on the molecule which forms said 
compound, in particular .sup.123 I , .sup.125 I, .sup.131 I. 
The selection of the radioactive isotope depends on the intended use of the 
ligand. 
For a utilization as imaging agent, for example, ligands labeled with 
.sup.99m Tc and also with .sup.111 In, .sup.113m In, .sup.67 Ga, .sup.68 
Ga, .sup.157 Gd, .sup.123 I, .sup.131 I, .sup.201 Ti, .sup.117m Sn will be 
used. 
For the purpose of targeted radiotherapy, the ligands will be labeled with, 
for example, .sup.125 I, .sup.131 I, .sup.64 Cu, .sup.186 Re, .sup.90 Y, 
.sup.212 Bi. 
A further subject of the present invention is therefore kits containing the 
ligands according to the invention and reagents which allow the formation 
of coordination complexes between said ligands and the metals mentioned 
above. 
The ligand can be in an aqueous/alcoholic solution or in lyophilized form. 
Said reagents are generally reducing agents, and stabilizers, such as 
paraaminobenzoic acid, or a base of which some examples are provided in 
the main patent application. 
In a preferred way of using the compounds according to the invention, the 
latter are utilized for complexing .sup.99m Tc for the purposes of medical 
imaging of the brain, the heart and infections, or for labeling 
lymphocytes for imaging inflammatory sites. 
The kits therefore contain the ligand and, as reducing agent, preferably a 
tin salt, such as stannous chloride. The metal compound used for 
reconstituting the kit is pertechnetate .sup.99m TCO.sub.4.sup.--. In the 
complexes formed, the technetium is probably in the form of the oxide Tc=O 
.

EXAMPLE 1 
SYNTHESIS OF THE LIGAND 
N-[2-(1H-pyrrolylmethyl]-N'-[4-(pent-3-en-2-one)]-ethylene-1,2-diamine 
(hereinafter MRP20) 
Compound of the formula I in which R.sub.1 =R.sub.3 =CH.sub.3 and R.sub.2 
=R.sub.4.sup.1 =R.sub.4.sup.2 =R.sub.5.sup.1 =R.sub.5.sup.2 =H and n=2 
1) Synthesis of N-[2-(1H-pyrrolylmethyl)]-ethylene-1,2-diamine 
A solution of 0.1 mol (9.5 g) of pyrrol-2-carboxaldehyde in 50 ml of dry 
acetonitrile is added under an argon atmosphere to a solution of 0.6 mol 
(40 ml) of ethylene-1,2-diamine in 80 ml of dry acetonitrile containing 2 
g of molecular sieve. The mixture is stirred overnight at ambient 
temperature. The solvent is evaporated in vacuo, and the residue is 
redissolved in 100 ml of reethanol. The resulting solution is placed in an 
ice-bath, and 0.1 mol of sodium borohydride is added in small portions 
with vigorous stirring. The reaction mixture is then stirred for 2 hours. 
Most of the methanol is evaporated in vacuo, and the resulting oil is 
redissolved in 100 ml of water. This solution is placed in an ice-bath, 
and 20 g of potassium hydroxide is added with vigorous stirring. The 
mixture is extracted with 5 times 50 ml portions of dichloromethane, the 
organic phases are then combined, dried over anhydrous potassium 
carbonate, filtered and then evaporated to obtain an oily residue which is 
subsequently placed in a water bath at 60.degree. C. and a vacuum is 
applied. Finally, 14 g of a viscous yellow oil are obtained (crude yield 
approximately 100%). A check by column chromatography on silica with a 
mixture of 5% ammonia in methanol as eluant indicates the presence of one 
main impurity which is more polar. This is eliminated by selectively 
precipitating its hydrochloride in ethanol. Finally, 10 g of a yellow oil 
are obtained (yield: 70%), which is sufficiently pure for the following 
steps. 
2) Synthesis of 
N-[2-(1H-pyrrolylmethyl)]-N'-[4-(pent-3-en-2-one)]-ethylene-1,2-diamine 
12 mmol (1.2 ml) of 2,4-pentanedione are added to a solution of 10 mmol 
(1.4 g) of 1) in 10 ml of acetonitrile. The mixture is allowed to stand in 
a nitrogen atmosphere for three hours at ambient temperature, and then the 
solvent is evaporated in vacuo. The oil which remains is then reextracted 
with a water/dichloromethane mixture. The organic phases which are dried, 
filtered and then evaporated provide a yellow oil which is purified on a 
silica column with a mixture of 0.5% diethylamine in ethyl acetate as 
eluant. The resulting final product is a pale yellow oil which 
resolidifies after refrigeration. Recrystallization from diisopropyl ether 
provides 1.5 g of immaculate crystals in the form of needles (yield: 66%). 
##STR23## 
Analytical Data 
NMR: shifts at ppm 11.2 (s,br) NHc; 9.6 (s,br) NHa; 6.75 (qu) 6.08 (qu) 
5.98 (tr) pyrrol; 5.0 (s) CH; 3.8 (s) CH.sub.2 ; 3.29 (qu), 2.83 (tr) 
CH.sub.2 --CH.sub.2 : 1.9 (s), 2.05 (s) Me, Me; 1.6 (s, br) NHb. 
Infrared 
N--H, 3174 cm--1, C.dbd.O, 1598 other bands are detected at 3090, 2972, 
2852, 1544, 1466, 1432, 1376, 1357, 1340, 1308, 1280, 1251, 1130, 1097, 
1028, 998. 
Mass Spectrometry 
ion corresponding to M/e 221.2: -Me 206.1: --C.dbd.O 178.1: peaks at 127, 
113, 98, 95, 84, 80 representing various stages of fragmentation. 
EXAMPLE 2 
SYNTHESIS OF THE LIGAND 
N-[2-(1H-pyrrolylmethyl)]-N'-[4-(5-trifluoropent-3-en-2-one)]-ethylene-1,2 
-diamine 
Compound of the formula I in which R.sub.1 =CF3, R.sub.3 =CH.sub.3, R.sub.2 
=R.sub.4.sup.1 =R.sub.4.sup.2 =R.sub.5.sup.1 =R.sub.5.sup.2 =H and n=2 
1 g of molecular sieve is added to a solution of 10 mmol (1.4 g) of the 
product obtained in Example 1, 1), in 15 ml of dichloromethane and the 
whole batch is placed in an ice-bath. 12 mmol (1.4 ml) of 
1,1,1-trifluoro-2,4-pentanedione are then added to the batch with 
stirring. The mixture is allowed to stand overnight in an argon 
atmosphere. The dichloromethane phase is washed once with water, dried and 
then evaporated, which provides a yellow oil. The product is purified by 
chromatography on silica with a mixture of 0.5% diethylamine in ethyl 
acetate as eluent. A pale yellow oil is obtained which resolidifies in the 
cold. The product is then recrystallized from a mixture of 5% of 
diisopropyl ether in hexane. 0. 9 g of white crystals in the form of fine 
needles is obtained (yield: 30%). 
##STR24## 
Analytical Data 
NMR: shifts at ppm 10.9 (s, br) NHc; 9.4 (s, br) NHa; 6.75 (qu), 6.08 (qu), 
5.98 (tr) pyrrol; 5.35 (s) CH; 3.85 (s) CH.sub.2 ; 3.38 (qu), 2.9 (tr) 
CH.sub.2 --CH.sub.2 ; 2.08 (s) Me; 1.6 (s, br) NHb. 
Infrared 
N--H 3365/3350 cm--1, C.dbd.O 1554 cm--1. Other bands have been observed at 
2863, 1605, 1372, 1252, 1125, 1021 cm--1. 
Mass Spectroscopy 
The molecular ion m/e 275 is accompanied by a fragment at 255 (loss of HF). 
The fragmentation diagram clearly indicates the presence of the pyrrole 
ring and of the ethylenediamine skeleton, while the collision spectra 
indicate additional losses of R. 
EXAMPLE 3 
Following the procedure of Examples 1 and 2, the following compounds of the 
formulae III (X pyrrolyl) have been prepared: 
______________________________________ 
1) Compound MRP22 
R.sub.1 = R.sub.3 = C(CH.sub.3).sub.3 
n = 2 R.sub.4 .sup.1 = R.sub.4 .sup.2 = R.sub.5 .sup.1 = 
R.sub.5 .sup.2 = 
R.sub.2 = H 
Spectroscopic data: 
NMR : shifts in ppm 
10.7 (s, bl) NH (c) 
10.2 (s, br) NH (a) 
6.77 (qu) 
6.09 (qu) 
5.99 (tr) pyrrolyl 
5.35 (5) 
3.90 (s) 
3.52 (qu) CH.sub.2 
2.90 (tr) 
1.5 (s, br) NH (b) 
1.32 (s) 
CH.sub.3 
1.2 (s) 
Mass: E1 70 ev 
M.sup.+ M/Z 305 amu 
fragments 248, 198, 196, 184, 169, 140 (BP), 80 
CHN: Calculated 
Found 
C 71.11 70.77 
H 10.23 10.40 
N 13.78 13.76 
2) Compound MRP30 
R.sub.1 = R.sub.3 = Me 
n = 3 R.sub.4 .sup.1 = R.sub.4 .sup.2 = R.sub.4 .sup.3 = 
H 
R.sub.5 .sup.1 = R.sub.5 .sup.2 = R.sub.5 .sup.3 = 
R.sub.2 = H 
Spectroscopic data: 
NMR: shifts in ppm 
11.08 NH (c) 
10.05 NH (a) 
6.75 (qu) 
6.99 (qu) 
5.99 (br) pyrrolyl 
4.97 (s) 
3.78 (s) 
3.35 (qu) CH.sub.2 
2.80 (tr) 
2.03 
CH.sub.3 
1.91 
1.75 (quadr) CH.sub.2 
1.6 (br) NH (b) 
Mass: EI 70 ev 
M.sup.+ M/Z = 235 (BP) 
fragments: 192, 157, 155, 126, 113, 98, 80 
CHN: Calculated 
Found 
C 66.88 67.64 
H 8.94 8.96 
N 17.87 17.71 
3) Compound MRP21 
R.sub.1 = Me R.sub.3 = CF.sub.3 
n = 3 R.sub.4 .sup.1 = R.sub.4 .sup.2 = R.sub.4 .sup.3 = 
H 
R.sub.5 .sup.1 = R.sub.5 .sup.2 = R.sub.5 .sup.3 = 
H = R.sub.2 
Spectroscopic data: 
NMR: shifts in ppm 
10.9 (S, br) NH (c) 
9.4 (S, br) NH (a) 
6.75 (qu) 
6.08 (qu) pyrrolyl 
5.98 (tr) 
5.35 (s) CH 
3.85 (s) 
3.38 (qu) CH.sub.2 
2.9 
2.08 (s) CH.sub.3 
1.6 (s, br) NH (b) 
Mass: EI 70 ev 
M/Z 275 amu.+ 
fragments M/Z 255, 166, 127, 109, 80 (BP) 
CHN: Calculated 
Found 
C 70.77 71.11 
H 10.23 10.40 
N 13.76 13.78 
4) Compound MRP30 
R.sub.1 = R.sub.2 = R.sub.3 = Me 
n = 2 R.sub.4 .sup.1 = R.sub.4 .sup.2 = R.sub.5 .sup.1 = 
R.sub.5 .sup.2 = H = R.sub.2 
Spectroscopic data: 
NMR: shifts in ppm (isomer mixture) 
12.15 (bv) NH c 
9.85 (bv) NH a 
6.90 
6.10 
6.05 pyrrolyl 
6.10 
4.26 (s) 
3.94 (s) 
3.60 (tr) CH.sub.2 
3.31 (qu) 
3.18 (tr) 
2.85 (tr) 
2.18 (s) 
2.04 (s) CH.sub.3 
1.94 (s) 
1.82 (s) 
1.70 (br) NH 
Mass: M.sup.+ M/Z 235 
fragments 221, 163, 127, 112, 110, 80 (BP) 
5) Compound MRP27 
R.sub.1 = R.sub.2 = ethyl 
n = 2 R/.sub.2 = R.sub.4 .sup.1 = R.sub.4 .sup.2 = 
R.sub.5 .sup.1 = 
R.sub.5 .sup.2 = R.sub.3 = H 
Spectroscopic data: 
NMR: shifts in ppm 
11.4 (br) NH (c) 
9.9 (br) NH (a) 
6.75 (qu) 
6.10 (qu) 
6.97 (tr) CH pyrrolyl 
5.00 (s) 
3.85 (s) 
3.32 (qu) CH.sub.2 
3.85 (tr) 
2.31 (qu) 
2.19 (qu) 
1.5 (br) NH b 
1.15 (quadr) CH.sub.3 
Mass: EI 70 ev 
M.sup.+ M/Z 249 
fragments 141, 128, 112, (BP), 80. 
______________________________________ 
EXAMPLE 4 
Synthesis of N-2-(pyridinylmethyl)-N'-4-(pent-3-en-2-one)-ethylenediamine 
(hereinafter named MRP-50) 
This compound has the formula 
##STR25## 
1. Synthesis of N-(2-pyridinylmethyl)-ethylenediamine 
1.1.--In a nitrogen atmosphere, 1 g of molecular sieve and then, very 
slowly, a solution of 1.9 ml (20 mM) of pyridine-2-aldehyde in 8 ml of 
acetonitrile are added to a mixture of 8 ml of ethylenediamine (120 mM) in 
20 ml of acetonitrile. The mixture is stirred overnight at ambient 
temperature. 
1.2.--most of the solvent is evaporated. 
20 ml of methanol are added, and the reaction flask is placed in an 
ice-bath. 
0.8 g (20 mM) of sodium borohydride is then added. 
The reaction medium is stirred for 2 hours at normal temperature. 
1.3.--The methanol is evaporated, and 20 ml of water are added to the 
residue. 
The solution is placed in an ice-bath. 4 g of KOH are added thereto. 
The mixture is extracted with CH.sub.2 Cl.sub.2. The organic phases are 
combined and dried over anhydrous K.sub.2 CO.sub.3. 
1.4.--After evaporation, 3.1 g of a reddish oil are obtained (crude yield: 
about 100%) TLC SiO.sub.2 MEOH/4% NH.sub.4 OH. 
2. Synthesis of 
N-2-(pyridinylmethyl)-N'-4-(Pent-3-en-2-one)-ethylenediamine 
2.1.--The 3.1 g of crude 1 (20 mM) are redissolved in 20 ml of CH.sub.3 CH. 
24 mM (2.4 ml) of acetylacetone are added. 
The mixture is allowed to react overnight with about 1 g of molecular sieve 
at ambient temperature, with stirring. 
2.2.--The maximum amount of solvent is evaporated. 
100 ml of water are poured in, and the mixture is extracted with CH.sub.2 
Cl.sub.2. 
The organic phases are dried, filtered and then evaporated, and 2. 8 g of a 
red-brown oil are obtained. 
TLC SiO.sub.2 /methanol indicates the presence of several colored 
impurities. 
2.3 Purification 
SiO.sub.2, ethyl acetate/0.5% DEA eluent 
The product partly decomposes in this system. 
Finally, 0.6 g of a yellow-red oil are obtained which shows a single spot 
in TLC on SiO.sub.2 /methanol. 
______________________________________ 
Mass spectrometry: 
MT M/Z 233 4% M/Z 121 
100% 
fragm. M/Z 176 3% M/Z 109 
20% 
M/A 147 12% M/Z 92 
27% 
______________________________________ 
NMR 1.92 S Me 2.01 S Me 2.82 tr CH.sub.2 --CH.sub.2 3.39 qu CH.sub.2 
--CH.sub.2 3.93 S CH.sub.2 
EXAMPLE 5 
Synthesis of 
N-[2-(N-(4-)pent-3-en-2-one)aminoethyl]-2-triphenylmethylthio)-acetamide 
(hereinafter MRP-40) 
The compound corresponds to the following formula: 
##STR26## 
1. Synthesis of N-(2-aminoethyl)-2-triphenylmethylthio)-acetamide 
The compound has the formula: 
##STR27## 
The reaction scheme is as follows: 
##STR28## 
1.1 Synthesis of N-(2-aminoethyl)-2-thioacetamide (1) 
1.1.1.--A solution of 33 ml (0.30 M) of ethyl thioacetate in 27 ml of 
absolute ethanol is added slowly to a solution, maintained under dry 
nitrogen at an internal temperature of 10.degree. C. (ice-bath), of 10 ml 
of ethylenediamine (0.15 M) in 50 ml of absolute ethanol. The mixture is 
allowed to react overnight at ambient temperature. 
1.1.2. The white precipitate is filtered rapidly, washed with alcohol and 
then with ether and then dried under a nitrogen atmosphere. 
17.6 g (yield=88%) of a white solid are obtained which is rapidly used in 
the following step. 
1.2 Synthesis of N-(2-aminoethyl)-2-(triphenylmethylthio)-acetamide (2) 
1.2.1.--28.25 g (0.11 M) of triphenylmethanol are added to a solution of 
13.4 g of (1) (0. 1 M) in 100 ml of trifluoroacetic acid. 
The resulting brown solution is stirred for 30 seconds and then evaporated 
in vacuo to give a dark brown oil. 
The latter is triturated with 500 ml of ether which gives a white 
precipitate which is filtered, washed with ether and dried in vacuo. 
51 g of a white powder are obtained (yield 80%). 
1.2.2.--10 g of 2 (20 Mm) are divided between 30 ml of 1 M NaOH and 100 ml 
of ethyl acetate. 
The organic phase is washed with water and then with water/salt, and dried 
over anhydrous potassium carbonate. 
The solution is filtered and then evaporated, and a yellow oil is obtained 
which is redissolved in 40 ml of ethanol. 
This solution is placed in the fridge overnight. 
The crystals which have formed are filtered, washed with hexane and dried. 
7.0 g of a creamy-white product are obtained (yield=90%). 
IR=3260, 3090, 3050 1630, 1550; 1485, 1440, 760, 750, 740. 
NMR .sup.1 H S1.23 (br S, 2H, NH.sub.2) 2.63 (m, 2H, CH.sub.2 NH.sub.2) 
2.99 (m, 2H, NHCH.sub.2) 3.13 (S, 2H, COCH.sub.2S) 6.36 (m, 1H, CONH) 
7.1-7.5 (m, 15H, aryl). 
2. Synthesis of 
N-[2-(N-(4-)-pent-3-en-2-one)aminoethyl]-2-(triphenylmethylthio)-acetamide 
2.1.--Under dry nitrogen; 1.88 g of 2 (5 mM) are dissolved in 15 ml of 
acetonitrile containing 0.5 g of molecular sieve. 0.6 ml (6 mM) of 
acetylacetone are added to this solution, and the mixture is allowed to 
react overnight at ambient temperature. 
2.2.--After the reaction mixture has been filtered and evaporated in vacuo, 
it provides a yellow oil which is purified over silica with a gradient of 
methanol in dichloromethane as eluent. Finally, 2.2 g of a yellow solid 
are obtained. 
2.3.--Recrystallization from a mixture of ethyl acetate and diisopropyl 
ether gives 1.52 g of white crystals (yield=65%). 
2.4. NMR .sctn. 1.63 (brS, 2H, NH.sub.2) 1.88 (S, 3H --CH.sub.3) 7.1-7.5/m, 
15Hm aryl 2.01 (S, 3H (CH.sub.3) 3.05 (m, 2H NHCH.sub.2) 3.13 (S, 2H 
COCH.sub.2 S) 3.18 (m, 2H CH.sub.2 NH). 
______________________________________ 
Mass spectrometry: 
______________________________________ 
M.sup.+ = 
M/Z 458 1% 
M/Z 243 100% 
M/Z 215 28% 
M/Z 165 37% 
______________________________________ 
EXAMPLE 6 
Synthesis of N-[4-(penten-3-one)]-N'-(2-pyrrolylmethyl)-glycinamide 
(hereinafter MRP26) 
The compound MRP26 corresponds to the following formula: 
##STR29## 
The reaction scheme is as follows: 
##STR30## 
1. Synthesis of N-Fmoc-N'-(2-pyrrolylmethyl)-glycinamide (4) 
1.1.--200 mg of 2-pyrrolylaminomethyl (2.09 mM) are dissolved in 10 ml of 
DMF containing 0.16 ml (2.2 mM) of triethylamine. 
1 g (2.09 mM) of Fmoc glyc OF.sub.5 phenyl is added rapidly. 
The mixture is stirred under a nitrogen atmosphere for 1 h. 
1.2.--The mixture is concentrated in vacuo, and the oil which remains is 
then extracted with a water/ dichloromethane mixture. 
1.3.--The yellowish oil which is obtained as a result of evaporation of the 
organic phases is recrystallized from CH.sub.2 Cl.sub.2 /hexane. Finally, 
0.77 g (1.9 mM) of cream crystals is obtained (yield approximately 90%). 
1.4.--Removal of the protection is effected with 9 ml of DMF+1 ml of DEA. 
After 1 h, most of the solvent is evaporated in vacuo. The crude product 
obtained is rapidly used in the condensation step. 
2. Synthesis of N-[4-(pent-3-en-2-one)]-N'-(2-pyrrolylmethyl)-glycinamide 
2.1.--Crude (4) is dissolved in 10 ml of CH.sub.3 CH under N.sub.2. 
0.4 ml (4 mM) of acetylacetone is added. 
After 15 minutes, a white precipitate is formed. The reaction mixture is 
kept stirred overnight. 
2.2.--Most of the solvent is evaporated in vacuo. The crude product is 
purified on a silica column with 0.5% DEA in ethyl acetate as eluent. 0.4 
g of a slightly yellow solid is isolated. 
2.3.--This is recrystallized from 15 ml of ethyl acetate. 
0.26 g of white crystals are obtained (final yield 50%). 
TLC CH.sub.2 Cl.sub.2 95/MeOH 5 AcOEt/0.5% DEA. 
NMR (ppm) 10.8 (s, bv); 9.4 (S, br); NH 6.75 (qu); 6.12 (qu), 6.01 (tr) 
pyrrole 5.1 (S) CH; 4.35 (d) CH.sub.2 ; 3.9 (d) CH.sub.2 1.85 (s); 2.05 
(s) CH.sub.3, CH.sub.3 ; 1.6 (S) NH. 
______________________________________ 
MASS (EI, 70 ev) 
M.sup.+ M/Z 235; fragments .fwdarw. 135, 112, 100, 94, 80 
Calculated 
Found 
______________________________________ 
CHN C-- 61.28 59.86 
H-- 7.29 7.18 
N-- 17.87 17.45 
______________________________________ 
EXAMPLE 7 
Synthesis of the Compound MRP210 of the Following Formula 
##STR31## 
which corresponds to the formula VI in which 
R.sub.1 =R.sub.3 =ethyl 
R.sub.2 =R.sub.4 =R.sub.5 H 
X=pyrrolyl 
The compound has been prepared following a protocol similar to that 
described in Example 9. 
______________________________________ 
10.84 (s.br) 
NH 
9.00 (s.br) 
6.71 (qu) 
6.08 (qu) pyrrole 
6.00 (s) 
5.14 (s) CH 
4.36 (d) CH.sub.2 
3.93 (d) 
2.32 (qu) 
2.14 (qu) 
1.5 (qu) CH.sub.3 
Mass (EI, 70 ev) 
M.sup.+ M/Z =0 2.63 
______________________________________ 
EXAMPLE 8 
Technetium Complex 
In an ethanolic salt solution, the above-described ligands react with 
pertechnetate (obtained from a commercial supplier) in the presence of a 
reducing agent (with or without base or stabilizer, for example 
paraaminobenzoic acid) to give technetium ligand complexes. The reducing 
agents can be selected from the following: tin(II), sodium dithionite, 
formamidinesulfinic acid, hydrazine or any other conventional reducing 
agent having an appropriate redox potential. 
1) Synthesis of the .sup.99m Tc 
N-[2-(1H-pyrrolylmethyl)]-N'-[4-(pent-3-en-2-one)]-ethylene-1,2-diamine 
4 mg of ligand, 1 ml of ethanol, 1 ml of an aqueous salt solution (NaCl 
0.9%), not more than 0.5 ml of an aqueous salt solution of .sup.99m 
TcO.sub.4.sup.-- and 20 .mu.g of SnCl.sub.2 freshly dissolved in 
de-gassed water are introduced in succession into a 10-ml flask. The 
mixture is allowed to react for 30 min at ambient temperature. TLC of the 
reaction products on silica gel (ITLC-SG) shows the presence of a 
lypophilic product which migrates with MEK (methyl ethyl ketone) and which 
does not migrate with an aqueous salt solution. The lypophilic compound 
can be chromatographed by HPLC and is retained on a reversed-phase 
chromatographic support. 
2) Synthesis of Complex 1) in the Presence of a Non-Coordinating Base 
4 mg of ligand, 5 mg of 1,2'-bipyridyl, 1 ml of ethanol, 1 ml of an aqueous 
salt solution, not more than 0.5 ml of a solution of .sup.99m 
TcO.sub.4.sup.-- and 20 .mu.g of SnCl.sub.2 freshly dissolved in 
de-gassed water are introduced in succession into a solution of 10 ml. The 
reaction is carried out as in Example 3.1). 
3) Synthesis of Complex 1) in the Presence of Hydroxyl Ions 
4 mg of ligand, 1 ml of ethanol and 1 ml of an aqueous salt solution are 
introduced in succession into a 10-ml flask. The pH is adjusted to 9.5 by 
means of NaOH. Not more than 0.5 ml of .sup.99m TcO.sub.4.sup.-- and 20 
.mu.g of SnCl.sub.2 are added. The reaction is carried out as in Example 
3.1). 
4) Synthesis of Complex 1) in the Presence of Paraaminobenzoic Acid 
4 mg of ligand, 80 .mu.g of paraaminobenzoic acid, 1 ml of ethanol, 1 ml of 
an aqueous salt solution, not more than 0.5 ml of a salt solution of 
.sup.99m TcO.sub.4.sup.-- and 20 .mu.g of SnCl.sub.2 are introduced in 
succession into a 10-ml flask. The reaction is carried out as in Example 
3.1). 
5) Synthesis of Complex 1) with Tin Tartrate 
4 mg of ligand, 1 ml of ethanol, 1 ml of an aqueous salt solution, not more 
than 0. 5 ml of an aqueous salt solution of .sup.99m TcO.sub.4.sup.-- and 
50 .mu.g of tin(II) tartrate in solution are introduced in succession into 
a 10-ml flask. The reaction is carried out as in Example 3.1). 
6) Synthesis of the 99.sup.99m Tc 
N-[2-(1H-pyrrolylmethyl)-N'-[4-(5-trifluoropent-3-en-2-one)]-ethylene-1,2- 
diamine complex 
Using 4 mg of ligand, the reaction is carried out as in Example 3.1). The 
retention time of the lypophilic compound which is obtained by HPLC is 
different from that of complex 1). 
7) Synthesis of Complex 1) at Different Temperatures 
4 mg of ligand, 1 ml of ethanol, 1 ml of an aqueous salt solution, not more 
than 0.5 ml of an aqueous salt solution of .sup.99m TcO.sub.4.sup.-- and 
20 .mu.g of SnCl.sub.2 are introduced in succession into a 10-ml flask. 
Flask and content are transferred to a water bath at 20.degree. C., 
40.degree. C. and 100.degree. C. for 30 minutes. The analyses are carried 
out as in Example 3.1). 
8) Synthesis of Complex 1) with Different Quantities of Reactants 
a) The reaction described in Example 3.1) is carried out using 1.4 mg of 
ligand in place of 4 mg of ligand. 
b) The reaction described in Example 3.1) is carried out using 5, 10, 20 
and 50 .mu.g of SnCl.sub.2. 
EXAMPLE 9 
Biodistribution of the MRP20 Complex 
A biodistribution study, in which the complex .sup.99m Tc 
N-[2-(1H-pyrrolylmethyl)]-N'-[4-(pent-3-en-2-one)]-ethylene-1,2-diamine 
(hereinafter MRP20) was used, was carried out on female Wistar rats. The 
animals received injections into the femoral vein and were killed at 
different intervals after the injection: 5 min, 15 min, 30 min, 60 min and 
180 min. Three animals were sacrificed at each of these different 
intervals. The organs of interest were removed and cleaned, the blood was 
removed, and a scintigraphic evaluation was then carried out with the aid 
of a gamma counter, starting with a standard sample prepared from the 
injected solution. The percentages of the doses injected per organ and per 
gram of tissue were calculated and are given in Tables 1 and 2, and a 
clearance curve is given in FIG. 1. 
Even through the initial fixation in the brain seems to be slow, the 
complex is retained for three hours and reaches a maximum of 2.35% of the 
dose injected per organ. This percentage is very satisfactory taking into 
account that it is currently administered by a cerebral tracer, namely 2 
to 3% of fixation in the rat brain, which generally corresponds to a 
fixation rate of more than 4-5% in primates. 
TABLE 1 
______________________________________ 
Percentage of the dose injected per organ 
MR20/RAT/DOSE/ORGAN 
ORGAN 5 min 15 min 30 min 60 min 
180 min 
______________________________________ 
blood 14.70 11.58 13.22 12.44 9.27 
brain 1.05 0.77 2.35 2.08 1.68 
heart 1.11 0.86 1.43 1.31 0.88 
liver 5.9 4.08 13.2 8.98 4.27 
kidneys 
2.41 3.66 5.84 6.45 7.95 
lung 1.97 1.23 2.21 2.05 1.31 
stomach 
0.88 1.14 2.85 2.51 1.73 
intestines 
2.69 5.67 9.32 9.89 15.27 
______________________________________ 
TABLE 2 
______________________________________ 
Percentage of the dose injected per gram of tissue 
MRP20/DOSE/GRAM 
ORGAN 5 min 30 min 60 min 
180 min 
______________________________________ 
blood 1.49 1.14 1.10 0.77 
brain 0.97 1.74 1.31 1.34 
heart 2.18 2.98 2.07 1.64 
liver 0.65 2.48 1.34 0.78 
kidneys 1.69 4.74 4.65 5.92 
lung 2.4 2.5 1.79 1.62 
stomach 0.36 0.92 0.79 0.79 
intestines 
0.12 0.92 0.68 1.32 
______________________________________ 
EXAMPLE 10 
Biodistribution of The MRP21, MRP22, MRP30, MRP27 and MRP26 Complexes 
A biodistribution study in which complexes of .sup.99m Tc of different 
compounds were used was carried out on female Wistar rats according to the 
following protocol. 
The animals received injections into the femoral vein and were killed at 
different intervals after the injection: 5 min, 15 min, 30 min, 60 min and 
180 min. Three animals were sacrificed at each of these different 
intervals. The organs of interest were removed and cleaned, the blood was 
removed, and a scintigraphic evaluation was then carried out with the aid 
of a gamma counter starting with a standard example prepared from the 
injected solution. The percentages of the doses injected per organ were 
calculated and are given in Tables 1 to 3, and a clearance curve is given 
in FIG. 2. 
1) Compound MRP22 of the formula 
##STR32## 
TABLE 1 
______________________________________ 
MR22/RAT/DOSE/ORGAN 
ORGAN 5 min 15 min 30 min 
60 min 180 min 
______________________________________ 
kidneys 
12.74 11.21 9.35 9.29 8.08 
liver 22.12 23.65 22.06 15.53 8.24 
stomach 
0.69 0.91 0.91 1.63 1.76 
lungs 0.84 0.51 0.32 0.32 0.25 
muscles 
0.15 0.05 0.05 0.02 0.01 
heart 0.38 0.13 0.10 0.07 0.04 
spleen 0.20 0.10 0.08 0.10 0.08 
intestines 
4.27 11.83 14.86 16.64 28.98 
heart 0.17 0.12 0.10 0.07 0.04 
blood 13.24 4.20 2.64 1.79 1.04 
______________________________________ 
##STR33## 
TABLE 2 
______________________________________ 
MRP30/RAT/DOSE/ORGAN 
ORGAN 5 min 30 min 3 hours 
______________________________________ 
brain 0.12 0.03 0.01 
heart 0.41 0.25 0.12 
blood 24.45 15.16 6.62 
liver 7.63 6.25 3.53 
kidneys 2.04 2.13 2.77 
stomach 6.11 16.62 23.04 
intestines 
5.95 8.21 17.3 
lungs 4.59 3.32 1.15 
______________________________________ 
##STR34## 
TABLE 3 
______________________________________ 
MRP21/RAT/DOSE/ORGAN 
ORGAN 5 min 30 min 1 hour 
3 hours 
______________________________________ 
blood 10.12 7.15 7.56 5.26 
brain 1.05 0.93 1.06 0.77 
heart 0.74 0.55 0.61 0.40 
liver 13.94 12.73 13.68 5.68 
kidneys 2.53 3.58 4.63 4.43 
lungs 1.22 0.98 1.15 0.70 
stomach 1.29 1.39 2.17 1.40 
intestines 4.6 7.99 17.69 17.04 
suprarenal glands 
0.21 0.14 0.12 0.08 
thymus 0.26 0.20 0.22 0.1 
______________________________________ 
##STR35## 
FIG. 3, which shows the percentage of the dose injected per organ over a 
period of time in rats, shows that the retention in the brain is similar 
to that of complex MRP20. 
The purification of the blood is as good in the case of MRP27 as in the 
case of MRP20. 
##STR36## 
FIG. 4, which shows a biodistribution curve of a .sup.99m Tc MRP26 complex 
in the rat, demonstrates in particular a very rapid elimination from the 
liver.