J.Med. Chem. 1984,27, 1077-1083 and a void volume at 1.42 min. With the above concentrations, the radiopurity and chemical purity were consistently in excess of 90%, and the radioincorporation efficiency was in the 30 to 40% range. The reaction gave similar results at 10 and 100 times these concentrations, but at one-tenth this concentration the yields were drastically reduced. Iodination of 7 to form Im and the direct synthesis of lm, when performed with lS1IClin acetic acid but in the absence of perchloric acid, resulted in a maximum radioincorporation of 12%.
Acknowledgment. This work was supported by National Institute of Mental Health Grant MH36801-02; by the Director, Office of Energy Research, Office of Basic Energy Sciences, Biology and Medicine Division of t h e D e p a r t m e n t of Energy under Contract DE-AC0376SF00098; and by t h e Donner Laboratory Schizophrenia Research Fund. Registry No. la, 90064-53-2; lb, 90064-54-3;IC, 90064-55-4; Id, 90064-56-5; le, 90064-57-6; lf, 90064-58-7; lg, 90064-59-8; lh,
1077
90064-60-1; li, 90064-61-2; lk, 90064-67-8; 11, 90064-62-3; l m (unlabeled), 85563-10-6; lmHC1 (unlabeled), 90064-51-0; lm, 90064-52-1; In, 90064-63-4; lo, 90064-64-5; lp, 90083-18-4; 1% 90064-65-6; 1r.HCl (unlabeled), 42203-78-1; lr, 65756-98-1; 2a, 51560-21-5; 2b, 90064-46-3; 3a, 90064-47-4; 3b, 90064-48-5; 3c, 7310-97-6; 4, 90064-44-1; 5a, 90064-49-6; 5b, 90064-50-9; 6, 14293-24-4;7, 67707-78-2; 7-oxalate, 90064-45-2;p-dimethoxybenzene, 150-78-7;N-methylformanilide,93-61-8; methanamine hydrochloride, 593-51-1; isopropylamine hydrochloride, 15572-56-2; cyclopropanemethanamine hydrochloride, 7252-53-1;hexanamine hydrochloride, 142-81-4;dodecanamine hydrochloride,929-73-7; benzenemethanamine hydrochloride, 3287-99-8; hydrazine hydrochloride, 14011-37-1;hydroxylamine hydrochloride, 5470-11-1; aminoacetonitrile hydrochloride, 6011-14-9; 24hioethanamine hydrochloride, 156-57-0; 2-methoxyethanamine hydrochloride, hydrochloride, 18600-40-3; N,N-dimethyl-1,3-propanediamine 77642-45-6; diethylamine hydrochloride, 660-68-4;N-methyl-2propananine hydrochloride, 54565-61-6; N-methylhexananine hydrochloride, 42870-70-2; N-methylbenzenemethanamine hydrochloride,13426-94-3;dimethylamine hydrochloride, 506-59-2.
Antihypertensives. N-1H-Pyrrol-1-yl-3-pyridazinamines Elvio Bellasio,* Ambrogio Campi, Nunzio Di Mola, a n d Emiliana Baldoli Research Laboratories of Gruppo Lepetit S.p.A., Via Durando 38, 20158 Milano, Italy. Received October 11, 1983 The hypothesis that the side effects of hydralazine, such as mutagenicity and lupus erythematosus like syndrome, might be due to the NHNHz group prompted us to incorporate part of this moiety into a pyrrole ring. Therefore, and a limited number of N-1H-pyrrol-1-yl-1we prepared a series of N-1H-pyrrol-1-yl-3-pyridazinamines phthalazinamines by reaction of 3-hydrazinopyridazines and 1-hydrazinophthalazines with y-diketones. Most of these compounds, especially in the pyridazine series, showed moderate to strong antihypertensive activity in spontaneously hypertensive rats. The decrease in blood pressure generally had a slow onset after either oral or intravenous administration. N-(2,5-Dimethyl-lH-pyrrol-l-yl)-6-(4-morpholinyl)-3-pyridazinamine hydrochloride (30) (MDL 899) showed no mutagenic activity in several tests and is now in clinical trials in patients.
The pathogenesis of hydralazine-induced lupus erythematosus has been correlated with its rate of hepatic acety1ation.l With t h e discovery of a novel urinary hydralazine metabolite in man, namely, 3-(hydroxymethyl)-striazolo[ 3,4-a]phthalazine, the hypothesis was advanced2 that the functional alcoholic group might provide a handle for the formation of a covalent bond to a protein and, thus, to production of antibodies to the metabolite. The recently discovered mutagenic activity of hydralazine3v4 could also be explained by the reactivity of the molecule itself. I n particular, t h e high reactivity of t h e hydrazine moiety N H N H z for carbonyl groups might cause other chemical modifications, resulting in toxic effects. This hypothesis prompted us to incorporate the terminal N H 2 group of some antihypertensive 3-hydrazinoyridazines into a pyrrole ring. Therefore, we prepared a few N-lH-pyrrol-l-yl-3pyridazinamines (VI, Scheme 11) and tested them for their hypotensive a n d mutagenic activity. T h e discovery that three compounds (29-31) endowed with good antihypertensive activity were not mutagenic led us to develop this class. Some compounds having a phthalazine moiety instead of pyridazine were also prepared. Chemistry. T h e last intermediates for t h e preparation of VI are hydrazino derivatives of general formula V (Table (1) B. N. La Du, H. G. Mandel, E. L. Way, ‘‘Fundamentalsof Drug
Metabolism and Drug-Disposition”; William & Wilkins: Bal. timore, 1971. H. Zimmer, R. Glaser, and J. Kokoea, J. Med. Chen., 18,1031 (1975).
J. Tosk, J. Schmeltz, and D. Hoffmann, Mutat. Res., 66, 247 (1979).
C. R. Shaw, M. A. Butler, J. Thenot, K. D. Haegle, and T. S. Matney, Mutat. Res., 68, 79 (1979).
III)(Scheme I), where R represents a tertiary amino group. References5r8 for those compounds already known are in Table IV. The new analogues were prepared starting from 3,6-dichloropyridazines I, which were reacted with secondary amines in t h e presence (method A) or absence (method B) of a solvent, t o give 3-amino-6-chloropyridazines I1 (Table I). The substitution of the chlorine atom with hydrazine to give V was achieved by one of the following three procedures. In the first procedure, reaction with hydrazine hydrate as a solvent (method F, R1 = H) was found t o be useful only when t h e final product had a relatively low water solubility. I n most cases, t h e isolation of V as t h e hydrochloride involved troublesome crystallizations in order t o satisfactorily eliminate hydrazine hydrochloride, and the final yields were generally very low. In some cases, after elimination of t h e hydrazine hydrate, the residues containing t h e compounds V were used as such for t h e synthesis of VI. I n the second procedure, compounds V were isolated as t h e benzalhydrazones I11 (Table 11), which were easily hydrolyzed in dilute mineral acids when concomitant steam distillation of t h e benzaldehyde was carried out (methods C and E). I n t h e third procedure, t h e hydrochlorides of I1 were reacted with tert-butyl carbazate in methylcellosolve, and after mild hydrolysis of t h e tert-butyl esters, t h e compounds V were isolated as the hydrazones I11 (method D). One compound, V-24, with a methyl on t h e hydrazino group (Rl = CH3) was prepared by methylation of t h e corresponding acetaldehyde hydrazone 111-15,followed by hydrolysis of t h e resulting compound IV. T h e correct position of t h e R1 methyl group was demonstrated by catalytic reduction to t h e aminopyridazine XI. T h e new intermediates V are reported in Table 111.
0022-2623/84/1827-1077$01.50/0 0 1984 American Chemical Society
1078 Journal of Medicinal Chemistry, 1984, Vol. 27, No. 8
Table I
Bellasio et al.
R44 \ N
R3
no. 1 2 3 4 5 6
R N(CH3)(CH2CH20CH3)a N(CH2CHZOCH3)z N(CH2CHZOCzH,)2 c-NC~H~ 2,6-Mez-c-N(CHzCH)20 4-OH-c-NC6Hio
n&
R4 H H H H H H H
R3
H H H H H H H
R
I1 mp or bp (mm), "C 68-69 115-118 (0.4)' 140 (0.2) 130-132 158-160 114-116 141-143
crystn solvent Et20 HzO EtOH HzO EtOAc
formula C8H&lN30 CloH&lN302* Ci2Hz,ClN302 CsHioClN3 CI0Hl4C1N30 CgHizClN30 Cl5HI7C1N40
anal. C,H,Cl, N C, H, C1, N C, H, C1, N C, H, C1, N C, H, Nd C, H, C1, N C, H, C1, N
method A B B A A A A
yield, %
65 41 77 58 53 42 70
W
c-N(CH~CH~)~O (CH2)4 129-130 EtOH C12H16ClN30 C, H, C1, N Be CHB 98-99 EtOH CloH,4C1N30 C, H, C1,N Bf 69 9 c-N(CHZCH2)20 CH3 149-152 EtOAc ClzHizClN30 C1, N A 70 10 C-N(CH~CH~)~O CH=CHCH=CH 11 4-OH-c-NCSHio CH=CHCH=CH 140-145 EtOAc C13H14ClN30 C, H, C1, N A 30 'For the preparation of N-methyl-N(2-methoxyethyl)amine, see W. R. Boon, J. Chem. SOC.,307 (1947). bHydrochloride: mp 131-132 "C (EtOAc). Oil which solidified, mp 33-34 "C. dN: calculated, 18.45; found, 17.57. e For the preparation of 1,4-dichloro-5,6,7,8-tetrahydrophthalazine, see R. H. Homing and E. D. Amstatz, J. Org. Chem., 20, 707 (1955). fFor the corresponding 3,6-dichloropyridazine,see E. Steck, R. P. Brundage, and L. T. Fletcher, J . Am. Chem. SOC.,76, 44 (1954). 8
Scheme I1
Scheme I'
V
method G R2CO(CH21$OR2 X method H
CH30QOCH3
c
lRp=Hl
I
R
VI-28-57
I
H2/P1
Rl\N/"2
RH methods A and B
/ I
! ?d
H+method E
'.fKHb ti,
+
VI-56
R R3$ )4
R
P
N
V-20-27
VI1
VI11 CH-R,
II
Rql CI I
method C
(11 NHNHp, (21 R&HO or method D
(11 NH~NHCOO+
R4
R
11-1-11
(21 HCI (31 RsCHO
R3qL H\,/fl
I
+
NOH-CH31-DMF
VI-39
R4
R
111-12-19
a RH = secondary amine. IV: R = c-N(CH,CH,),O; R, = R, = CH,; R,, R, = H. XI: R = c-N(CH,CH,),O; R, = CH,; R,, R, = H.
The preparation of N-1H-pyrrol-1-yl-3-pyridazinamines VI, substituted in the 2- and 5-positions of the pyrrole ring, was carried out by reaction of V with y-diketones (method G) in acetic acid. Sodium acetate was added when the
W VI-30 (MDL899 base)
IX
compounds were used either as salts or as crude products obtained through method F. The y-diketones used were acetonylacetone and 3,6-octanedione. (5) E. Bellasio, F. Parravicini, and E. Testa, Furmuco, Ed. Sci., 24, 919 (1969).
Journal of Medicinal Chemistry, 1984, VoE. 27, No. 8
N - 1H-Pyrrol- 1-yl-3-pyridazinamines
I
II
1079
v)
s U
r L
o d L a
VJW
M M
t-
M
1080 Journal of Medicinal Chemistry, 1984, Vol. 27, No. 8
Bellasio et al.
Table IV
no. 28 29
30 31 32 33 34 35 36 37 38 39 40 41 42
R N(CH2CH20C2H& N(CH2CH20CH3)2 c-N(CH~CH~)~O N(c~H~)~ N(CHJ(CHzCH20CH3) N(CHs)(CH2CHOHCH3) c-NC~H~O N(CH2CH=CH2)2 c-N(CH~CH~)~O 4-OH-c-NC5Hio c-N(CH&H2)20 c*N(CHZCH2)20 C-N(CH~CHZ)~O 2,6-Mez-c-N(CHCH)20
p&
R1
R3 H H H H H
R4 H H H H H
mp or bp yield, % (mm), OC (method) formula anal. 180 (0.2) 70 (GI Ci~H2gN602 C, H, N 112-114' 57 (G) C16H25N502 C, H, N 260 decd 61 (GY C14H19N50.HCI C, H, N, C1 149-150d 29 (G)' C,,HmN, C. H. N 105-106e C; H; N 52 (G) C;;H;;N,O
1% P a EDgOb 2.06 1.94 2.73 2.16
2 2.7 3.9 3.9 7
C, H, N
1.73
7.7
3.13 1.70
11.4
H H H H H
Rz CH3 CH3 CH3 CH, CHj
H
CH3 H
H
139-140'
62 (GI'
H H COCHS H H CH3 CH3 H
CH3 CH3 CH3 CH3 C2H5 CH3 H CH3
185-187' 135-136e 162-16&' 175-177' 186-18gd 119-1228 105-117e9h 147-14Se
27 (G)p 37 (G)s 63P 28 (G)"'
H H H
H H H H H H H H
C15H21N5 C16Hz1N6 C18H21N502*HCl C15H21N60 41 (G)p ClGH23N50 49 (G)p C15H21N50 50 (H) C13H17N50 45 (G)',t C16H23N50
C, H, N C, H, N C, H, N, C1 C, H, N C, H, N C, H, N C, H, N C, H, N
1.70 2.71 2.21 2 2.59
H
CH3 H
H
194-196'
51 (G)'tt
C, H, N
3.61
H H H H
C14H21N50
C21H26N60
1.64
10
11.8 12.6 15.4 15.8 16.5 18.5 -20
H CH3 H H 165-167e 50 (G)' C12H17N5 C, H, N 2.18 -22 H CH3 H H 202-203' 50 (G)' C14HlgN5S C,H,N,S n -25 H CH3 CH3 H 196-198' 23 (G)g C15H21N5O C,H,N n -26 46 c-N(CH2CHz)ZNH H CH3 H H 189-191' 18 (G) C14H20N6 C, H, N 1.44 30 47 c-N(CHZCH2)20 H CH3 -(CH2)4236-237' 62 (G) CleH25N50 C, H, N n -33 48 4-OH-c-NC5H10 H CH3 CH=CHCH=CH 184-186' 40 (G)"J ClBH23NsO C, H, N n -33 49 c-N(CH~CH~)~O H CH3 CH3 CH3 234-239' 57 (G) C16H23N6O C, H, N n 35 H~ ) ~ N CH3 H H 180-182' 50 ~ - M ~ - C - N ( C H ~ C H C,H, N 1.94 -43 21 (G)" C16H22N5 CH3 H H 137-139' 40 (G)' C16H2~N502 C, H, N 1.55 -54 51 N(CH2-CHOHCH&2 H CH=CHCH=CH 205-209"' 28 (G)"' C ~ ~ H Z ~ N ~C, H CH3 52 c-N(CH2CHrJ20 OH,N n -91 CH3 H H 53 N(CH2CH20H)(CH2 H 40 (G) C15H23N502 C, H, N 1.30 >lo0 129-131' CHOHCH,) 54 C - N C ~ H ~ H CH3 H H 208-209' 42 (G)'$t C14HlgNh C, H, N 2.45 >lo0 55 N(CHZCH20H)2 H CH3 H H 129-131' 39(G)" C16H23N502 C, H, N 1.06 >lo0 56 C*N(CH~CH~)~O H H H H 228-229' 2 (H) C12H15N60 C, H, N n >lo0 57 H H CH3 CH=CHCH=CH 170-171' 15 (G) C14H14N14 C, H , N n nP = partition coefficient, octanol-phosphate buffer, pH 7.4. bOraldose in milligrams per kilogram produces a 30 mmHg drop of systolic blood pressure (calculated on the regression line), 'EtOAc. di-PrOH. e EhO. fi-PrOH-EhO. gHexane. Mixture of three crystalline forms melting at 105, 113 and 117 "C. 'EtOH. jDeleted on revision. 'CH3CN. "Me2C0. "Not determined. 'Overall yield from the corresponding chloropyridazine or phthalazine. P For the corresponding hydrazino derivative V, see ref 5. 9 For the corresponding hydrazino derivative V, see ref 6. 'For the corresponding hydrazino derivative V, see ref 7. *For the corresponding hydrazino derivative V, see ref 8. tThe corresponding hydrazino derivative V was not isolated. N: calcd. 20.75; found, 20.10. 43 N(CH3)z 44 c-N(CH~CH~)~S 45 c-N(CH2CH2)zO
Two compounds that were unsubstituted in the pyrrole ring were obtained by reaction of V with 2,5-dimethoxyfuran (method H) in ethanol, in the presence of hydrogen (6) E. Bellasio, A. Ripamonti, F. Parravicini, and E. Baldoli, Farmaco, Ed. Sci., 27, 581 (1972). (7) G. Pifferi, F. Parravicini, C. Carpi, and L. Dorigotti, J. Med. Chem., 18, 741 (1975). (8) P. L. Anderson, W. J. Houlikan, and R. E. Manning, German Offen. 2 062 107, 1970. (9) K. Okamoto, K. Aoki, Jpn. Circ. J.,27, 282 (1963). (10) E. Baldoli, unpublished results. (11) V. Dezulian, personal communication. (12) A Goldblatt, J. Linch, R. F. Hanzal, and W. W. Summerville, J.Exp. Med., 59, 347 (1934). (13) B. P. Goldstein, F. Ripamonti, and F. Rodenghi, 12th Annual
Meeting of the European Environmental Mutagen Society, Helsinky, June 20-24, 1982. (14) A. Assandri, personal communication. (15) R. A. Coburn and R. A. Carapellotti, J. Pharm. Sci., 65, 1505 (1976). (16) H. Stetter, Angew. Chem., Int. Ed. Engl., 15, 639 (1976).
chloride. This reaction proceeded with fairly good yield
to give compound VI-40 when we started from V-24, which has a CH3NNH2group. In contrast, the reaction carried out on VII, which has an unsubstituted hydrazino group, gave only traces of the corresponding pyrrole derivative VI-56 and a slightly greater amount of the dihydropyridazine VIII. Compound VI-39 was also prepared by methylation of VI-30 in the presence of sodium hydride. In this case a derivative (IX) methylated on the pyridazine nitrogen was also formed. Biological Activity. The antihypertensive activity of t h e compounds VI is reported in Table IV as the oral effective dose (ED30) t h a t produced a drop of 30 mmHg in spontaneously hypertensive rats.g No correlation between pharmacological activity and octanol-water partition coefficient was found. The amino group R is necessary for activity; a small number of N-1H-pyrrol-1-yl-3-pyridazines VI without this moiety, recently prepared and not reported in this paper, were shown to be inactive." Also in the phthalazine series, compound VI-57, obtained from hy-
Journal of Medicinal Chemistry, 1984, Vol. 27, No. 8 1081
N - 1H-Pyrrol-l- yl-3-pyridazinamines
Table V. Effects of MDL 899 and Hydralazine, Given Intravenously, on Systolic Blood Pressure and Heart Rate in Conscious Renal Hypertensive Dogs" systolic blood pressure, mmHg, at the following times treatment Oh 4h 6h 8h 10 h 12 h 20 h 187 f5 147 f 8 165 f 5 140 f 7 150 f 5 168 f 8 190 f 10 MDL 899,l mg/kg 188 f 7 188 f 7 190 f 4 148 f 5 138 f 2 135 f 5 188 f 7 hydralazyne, 0.3 mg/kg
