- Efficient and regioselective bromination of aromatic compounds with ethylenebis(N-methylimidazolium) ditribromide (EBMIDTB)
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A regioselective and highly efficient method for bromination of phenol and aniline derivatives using ethylenebis(N-methylimidazolium) ditribromide (EBMIDTB) as an efficient reagent in dichloromethane at ambient temperature is reported. The reagent can be recovered and reused several times.
- Hosseinzadeh, Rahman,Tajbakhsh, Mahmood,Mohadjerani, Maryam,Lasemi, Zahra
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- HEMOGLOBIN MODIFIER COMPOUNDS AND USES THEREOF
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Described herein are compounds, including pharmaceutically acceptable salts thereof, methods of making such compounds, pharmaceutical compositions comprising such compounds, and methods of using such compounds to treat, prevent or diagnose blood-based diseases, disorders or conditions.
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Paragraph 00639-00640
(2018/02/28)
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- Synthesis of chiral pilocarpine analogues via a C-8 ketone intermediate.
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The synthesis of a chiral pilocarpine analogue 3 in which the lactone ring is replaced by an oxazolidinone and the bridging methylene group is in the ketone oxidation state has been accomplished. The utility of this compound as a key intermediate for the preparation of more complex structures was demonstrated by its reduction to two alcohol epimers and its reaction with a methylene ylide.
- Holden, Kenneth G,Mattson, Matthew N,Cha, Kyung Hoi,Rapoport, Henry
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p. 5913 - 5918
(2007/10/03)
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- Carbodesilylation of (Trimethylsilyl)imidazoles and -pyrazoles
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The preparation of the 1-methyl(trimethylsilyl) (TMS)-substituted imidazoles 3a, 4a, 8, 9, and 11a by silylation of the corresponding metallated imidazoles is described.Carbodesilylation of 3 with aldehydes or carboxylic halogenides occurs selectively in 2-position.In the presence of a strong base (CsF) the reactivity against carbon electrophiles correlates well with the stability of the imidazolyl anions; regioselective carbodesilylation in 2-, 5-, or 4-position of the twofold TMS-substituted imidazoles 3a and 9 therefore is possible, which allows the synthesis of a great variety of hydroxyalkyl-substituted imidazoles and of acylimidazoles.By using the dimethylsulfamoyl substituent as an N-protecting group, the N-unsubstituted 5-benzoylimidazole (26) as well as the comparable 5-benzoyl-pyrazole (30b) and 5-(hydroxyphenylmethyl)pyrazole (30a) are accessible. Key Words : Imidazoles, (trimethylsilyl)-, carbodesilylation of / Pyrazoles, (trimethylsilyl)-, carbodesilylation of / Carbodesilylation
- Effenberger, Franz,Roos, Michael,Ahmad, Roshan,Krebs, Andreas
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p. 1639 - 1650
(2007/10/02)
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- A General Route to 4-Substituted Imidazoles
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Literature routes to di(imidazol-4-yl)methanol (1a) dinitrate and tri(imidazol-4-yl)methanol (2a) trihydrochloride were improved to give 32 and 16percent overall yields, respectively; but we failed to synthesize bis- (1b) and tris-(1-methylimidazol-4-yl)methanol (2b) by the methylation of the corresponding N-methoxymethyl compounds (3; x=2 and x=3).Attempted 4-lithiation of the 1,2,5-protected imidazole (4a) with BuLi-TMEDA failed, giving after hydrolysis 1-methyl-5-trimethylsilylimidazole (4b); similar failures were observed for 2,5-dicarboxy-1-methylimidazole, which after metallation with BuLi-TMEDA and hydrolysis afforded 1-methylimidazole-5-carboxylic acid (5).Our attempts to obtain 4-bromo-1-methylimidazole (10a) and 4-bromo-1-ethylimidazole suitable for a halogen-lithium exchange or for Grignard reaction also failed.Attempted selective lithiation of 2-phenylthio-1-tritylimidazole (16) at the 4-position, then theatment with ethyl formate, led only to a mixture of 4- and 5-substituted products in very low yield, and 1-diethoxymethyl-2-phenylthioimidazole (18) was unstable and difficult to purify. 4-Bromoimidazole with two mol equiv. of t-butyl-lithium gives 1,4-dilithioimidazole, which is now shown to provide a general route to 4-substituted imidazoles.
- Katritzky, Alan R.,Slawinski, Jaroslaw J.,Brunner, Frederic,Gorun, Sergiu
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p. 1139 - 1145
(2007/10/02)
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- Convenient Synthesis of Methyl 1-Methyl-2,4-dibromo-5-imidazolecarboxylate
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Three syntheses of methyl 1-methyl-2,4-dibromo-5-imidazolecarboxylate (8) are presented.One proceeds from sarcosine via ring closure, bromination, and desulfurization.The second uses N-methylimidazole, polybromination, and selective halogen-metal interchange.The third and most efficient and preparatively useful route begins with diaminomaleonitrile (13).Ring closure with triethyl orthoformate followed by methylation and hydrolysis affords 1-methyl-4,5-imidazoledicarboxylic acid (16).Regioselective decarboxylation followed by esterification yields methyl 1-methyl-5-imidazolecarboxylate (18).Subsequent dibromination gives the completely substituted imidazole 8.The primary purification in this sequence is fractional sublimation of 18 after the esterification step.An overall yield of 26percent is achieved from diaminomaleonitrile (13) to methyl 1-methyl-2,4-dibromo-5-imidazolecarboxylate (8), which is a key intermediate for the synthesis of tricyclic imidazo cooked food mutagens.
- O'Connell, John F.,Parquette, Jonathan,Yelle, William E.,Wang, Wilhelm,Rapoport, Henry
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p. 767 - 771
(2007/10/02)
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