Reaction of γ-bromodipnone with hydrazines [10]

Full text of DOI:10.1007/s10593-007-0083-0

Chemistry of Heterocyclic Compounds, Vol. 43, No. 4, 2007
REACTION OF γ-BROMODIPNONE WITH HYDRAZINES
L. M. Potikha and V. A. Kovtunenko
Keywords: γ-bromodipnone, 1,3,5-triarylpyridazine tribromides, 2,4-diphenyl-1H-pyrrol-1-amine,
1,3,5-triphenyl-1,4-dihydropyridazine.
4-Bromo-1,3-diphenyl-2-buten-1-one (γ-bromodipnone) (1) reacts readily with amines to give
N-substituted derivatives of 2,4-diphenylpyrrole [1,2]. The reaction of hydrazine with γ-halocarbonyl
compounds gives, depending on their structure, derivatives of N-aminopyrrole [3] or hydrazine [4]. We have
observed that on heating γ-bromodipnone 1 with hydrazine hydrate in ethanol 2,4-diphenyl-1H-pyrrol-1-amine
(2) was formed, while with arylhydrazines under the same conditions 1-aryl-1,4-dihydropyridazine or 1-aryl-
1-pyridazilium salts formed, the nature of the products depending on the nature of the substituents in the benzene
ring. For example, 1,3,5-triphenyl-1,4-dihydropyridazin (3) was formed when a mixture of 1 and
phenylhydrazine was boiled for a short time (15 min), but with 1-(2methylphenyl)- and 1-(3-methyl-
phenyl)hydrazines the products were 1-aryl-3,5-diphenyl-1-pyridazinium bromides 4a,b. The structures of the
reaction products 2-4 were established by spectroscopic methods. Conclusive evidence of the structures of
compounds 3 and 4 were obtained using homonuclear (COSY and NOESY) and heteronuclear (HMBC and
HMQC) two dimensional correlation NMR spectroscopy.
Ph
Ph
Ph
Ph
Ph
N
COPh
Br
N
N
Ph
3
1
NH2
2
Ph
Ph
N
+
N
–
Br
R
4a,b
4 a R = 2-MeC6H4, b R = 3-MeC6H4
1H NMR spectra of DMSO-d6 solutions with TMS as internal standard were recorded with a Varian
Mercury 400 (400 MHz) machine.
2,4-Diphenyl-1H-pyrrol-1-amine (2). A mixture of -bromodipnone (1 g, 3.32 mmol) and hydrazine
hydrate (2.6 ml 80%) in ethanol (50 ml) was heated until the -bromodipnone had dissolved completely and the
mixture was then kept for 10 h at room temperature. The precipitate was filtered off and washed with ethanol.
__________________________________________________________________________________________
Tara Shevchenko National University, Kiev 01033, Ukraine; e-mail potikha-l@mail.ru. Translated from
Khimiya Geterotsiklicheskikh Soedinenii, No. 4, 626-628, April, 2007. Original article submitted November 10,
2006
0009-3122/07/4304-0523©2007 Springer Science+Business Media, Inc.
523

Yield: 0.47 g (61%); mp 143-145°C (from 2-propanol). 1H NMR spectrum, δ, ppm (J, Hz): 7.70 (2H, d, 3J = 8.0,
H-2',6'), 7.47 (2H, d, 3J = 8.0, H-2",6"); 7.34 (2H, d, 3J = 8.0, H-3',5'); 7.26 (2H, t, 3J = 8.0, H-3",5"); 7.20 (1H, t,
4
3
3
3J = 8.0, H-4'); 7.15 (1H, d, J = 1.6, H-5); 7.07 (1H, t , J = 8.0, H-4"); 6.46 (1H, d, J = 1.6, H-3); 5.76 (2H,
br. s, NH2). Found, %: C 82.34; H 6.12; N 11.88. C16H14N2. Calculated, %: C 82.02; H 6.02; N 11.96.
1,3,5-Triphenyl-1,4-dihydropyridazine (3). A mixture of g-bromodipnone (1 g, 3,32 mmol) and
phenylhydrazine (0.33 ml, 3.32 mmol) was boiled for 15 min. The solvent was evaporated and the residue
1
recrystallized from ethanol. Yield 0.63 g (61%); mp 131-133°C (from EtOH). H NMR spectrum, δ,
ppm (J, Hz): 8.00 (2H, d, J = 8.0, H-2",6"); 7.72 (1H, s, H-6); 7.66 (4H, m, H-2',6',2"',6"'); 7.50-7.36 (7H, m,
H-3',5',H-3"-H-5", H-3"',5"'); 7.24 (1H, t, J = 8.0, H-4"') 7.04 (1H, t, J = 8.0, H-4'); 3.64 (2H, s, C(4)H2).
Found, %: C 85.41; H 5.93; N 8.99. C22H18N2. Calculated, %: C 85.13; H 5.85; N 9.03.
3
3
3
1-Aryl-3,5-diphenyl-1pyridazinium bromides (4a,b). A mixture of 1-(2-methylphenyl)- or 1-(3-
methylphenyl)hydrazine hydrochloride (0.53 g, 3.32 mmol) and NaHCO3 (0.28 g, 3.32 mmol) was heated in
ethanol (50 ml) for 10 min and the solid precipitate was filtered off. γ-Bromodipnone (1 g, 3.32 mmol) was
added to the filtrate and the mixture was boiled for 30 min. The solvent was evaporated and the residue was
recrystallized from AcOH.
1
Compound 4a. Yield 0.6 g (45%); mp 275-277°C (dec., from AcOH). H NMR spectrum, δ,
ppm (J, Hz): 10.59 (1H, s, H-6); 9.56 (1H, s, H-4); 8.42 (4H, m, H-2",6", H-2"',6"'); 7.97 (1H, d, 3J = 8.0, H-6');
7.70-7.56 (9H, m, H-3'-5', H-3"-5", H-3"'-5"'); 2.41 (3H, s, CH3). Found, %: Br 19.85; N 6.94. C23H19BrN2.
Calculated, %: Br 19.81; N 6.95. C
1
Compound 4b. Yield 0.53 g (40%); mp 260-263°C (dec., from AcOH). H NMR spectrum, δ, ppm (J,
Hz): 10.59 (1H, s, H-6); 9.49 (1H, s, H-4); 8.43 (4H, m, H-2",6", H-2"',6"'); 8.14 (1H, s, H-2') 8.09 (1H, d,
3J = 8.0, H-6'); 7.71-7.60 (8H, m, H-4',5', H-3"-5", H-3"'-5"'); 2.59 (3H, s, CH3). Found, %: Br 19.79; N 6.93.
C23H19BrN2. Calculated, %: Br 19.81; N 6.95.
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