- Synthesis of novel pyridazinonylbenzotriazoles
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4-Chlorobenzaldehyde (1) was reacted with crotononitrile (2) in the presence of sodium cyanide yielding 4-(4-chlorophenyl)-3-methyl- 4-oxobutyronitrile (3) which on refluxing with concentrated HCl gave 4-(4-chlorophenyl)-3-methyl-4-oxobutyric acid (4). The latter, on treatment with fuming nitric acid, yielded 4-(4-chloro-3-nitrophenyl)-3-methyl-4-oxobutyric acid (5), which on treatment with hydrazine hydrate gave 6-(4-chloro-3-nitrophenyl)-5-methyl-4,5-dihydro-2H-pyridazine-3-one (6). Azidation and reduction of 6 with sodium azide gave the amino derivative 7 which on reductive alkylation gave 10(a-i) followed by reduction with commercially available sodium hydrogen sulphide solution gave the substituted diamine derivative 11(a-i). The compound 7 directly undergoes reduction with sodium hydrogen sulphide yielding (8). Finally, 8 and 11(a-i) was converted into the target compounds by diazotized-cyclization with sodium nitrite giving pyridazinonylbenzotriazoles 9 and 12(a-i).
- Reddy, S. Shashidhar,Vineel, B. George,Venkataiah,Naidu,Dubey
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p. 3633 - 3638
(2015/12/24)
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- Synthesis of novel Pyridazinonylbenzotriazoles
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4-Chlorobenzaldehyde (1) was reacted with crotononitrile (2) in the presence of sodium cyanide yielding 4-(4-chlorophenyl)-3-methyl-4-oxobutyronitrile (3) which on refluxing with concentrated HCl gave 4-(4-chlorophenyl)-3-methyl-4-oxobutyric acid (4). The latter, on treatment with fuming nitric acid, yielded 4-(4-chloro-3-nitrophenyl)-3-methyl-4-oxobutyric acid (5), which on treatment with hydrazine hydrate gave 6-(4-chloro-3-nitrophenyl)-5-methyl-4,5-dihydro-2H-pyridazine-3-one (6). Azidation and reduction of 6 with sodium azide gave the amino derivative 7 which on reductive alkylation gave 10(a-i) followed by reduction with commercially available sodium hydrogen sulphide solution gave the substituted diamine derivative 11(a-i). The compound 7 directly undergoes reduction with sodium hydrogen sulphide yielding (8). Finally, 8 and 11(a-i) was converted into the target compounds by diazotized-cyclization with sodium nitrite giving pyridazinonylbenzotriazoles 9 and 12(a-i).
- Shashidhar Reddy,George Vineel,Venkataiah,Naidu,Dubey
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p. 3633 - 3638
(2015/12/30)
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- CRYSTALLINE PIMOBENDAN, PROCESS FOR THE PREPARATION THEREOF, PHARMACEUTICAL COMPOSITION AND USE
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The invention relates to a pharmaceutical composition containing pimobendan as an active ingredient. The invention also relates to a crystalline form of pimobendan, as well as to a combination of said crystalline form with at least one other therapeutically active ingredient. Moreover, the invention relates to uses of said crystalline form, as well as to a pharmaceutical composition containing it. Finally, the invention relates to a process for preparing a crystalline form of pimobendan.
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Page/Page column 4-5
(2011/07/06)
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- Carbon-carbon bond cleavage of α-substituted benzoins by retro-benzoin condensation; A new method of synthesizing ketones
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When α-benzylbenzoin (3a, α-benzyl-α-hydroxybenzyl phenyl ketone) was treated with potassium cyanide (1) in N,N-dimethylformamide at 80°C for 1h, the carbon-carbon bond was cleaved, resulting in the formation of deoxybenzoin (4a, benzyl phenyl ketone) and benzaldehyde (2a). This carbon- carbon bond cleavage proceeds through a retro-benzoin condensation mechanism. This method of synthesizing ketones was applied to several α-substituted benzoins (3), and the corresponding ketones (4) were formed in good yields. Further, we found that the cyanide ion-donating ability of tetrabutylammonium cyanide (6, Bu4NCN) is more effective than that of potassium cyanide (1, KCN). As expected from the chemical analogy between cyanide ion and azolium ylide, several azolium salts (7) can also be employed in the retro-benzoin condensation as catalysts. The benzoin derivatives 3 were synthesized in the following three ways; reaction of alkyl halide (9) with benzoin (5), Michael addition of benzoin (5) with acceptors (10), and Grignard reaction of benzils (8). Alkylation of the benzoins without isolation, followed by carbon-carbon bond cleavage, readily afforded the corresponding ketones (4).
- Miyashita, Akira,Suzuki, Yumiko,Okumura, Yoko,Iwamoto, Ken-Ichi,Higashino, Takeo
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- Synthesis of ketones by retro-benzoin condensation catalyzed by potassium cyanide
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The treatment of 2-benzyl-1,2-diphenyl-2-hydroxyethanone (3a, benzylbenzoin) with potassium cyanide in DMF gave deoxybenzoin (4a). The formation of deoxybenzoin (4a) proceeds through retro-benzoin condensation by catalytic action of cyanide ion. Similarly, retro-benzoin condensation applied to several substituted benzoins 3 resulted in the formation of the corresponding ketones 4 in excellent yields.
- Miyashita,Suzuki,Okumura,Higashino
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p. 252 - 254
(2007/10/03)
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