- The reaction of carbonyldiimidazole with alcohols to form carbamates and N-alkylimidazoles
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The reactions of non-benzylic primary and secondary aliphatic alcohols with carbonyldiimidazole (CDI) afford the corresponding carbamates but not N-alkylimidazoles. For benzylic primary alcohols, formation of N-alkylimidazoles proceeds reasonably at 170 °C in several different solvents and occurs by way of the initially formed carbamate. However, under these rather forcing conditions, or even at lower reaction temperatures, elimination is a significant side reaction for benzylic secondary alcohols with β-hydrogen atoms. With one exception, reactions of six N,N-disubstituted β-aminoalcohols with CDI to form N-alkylimidazoles proceed under relatively mild conditions and may occur by way of an aziridinium intermediate.
- Tang, Yuanqing,Dong, Yuxiang,Vennerstrom, Jonathan L.
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p. 2540 - 2544
(2007/10/03)
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- High-yield synthesis of novel imidazoles and triazoles from alcohols and phenols
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A variety of alcohols and phenols are converted into their corresponding imidazoles and triazoles in high yields by a facile reaction with N,N1-carbonyldiimidazole (CDI) or N,N1-carbonylditriazole (CDT) in acetonitrile. The reactions of allylic alcohols, enols and phenols with CDI or CDT are unprecedented. Evidence is provided which suggests that the reaction with alcohols proceeds via the corresponding carbamates by an S(N)i mechanism.
- Njar
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p. 2019 - 2028
(2007/10/03)
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- An improved and convenient procedure for the synthesis of 1-substituted imidazoles
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1-Protected imidazoles, such as 1-acetyl- and 1-benzoylimidazoles, react with various halides, such as benzyl, allyl, α-keto, and alkyl halides, to give 1-protected-3-substituted imidazolium salts in high yields. The resultant imidazolium salts are easily deprotected by treatment with water or alcohols to give the corresponding 1-substituted imidazoles in excellent yields. In this reaction the yields of 1-substituted imidazoles vary with the kinds of halides used and/or with the protecting groups, and the yields increase in the following order: benzyl halides≥allyl halides~α-keto halides>alkyl halides, and acetyl≥benzoyl>ethoxycarbonyl>diethoxymethyl>trimethylsilyl>tosyl.
- Kamijo,Yamamoto,Harada,Iizuka
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p. 1213 - 1221
(2007/10/02)
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- Imidazole derivatives and salts thereof
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1-Substituted-imidazoles of the formula: STR1 in which A is selected from the group consisting of straight or branched, saturated or unsaturated, acyclic hydrocarbon radicals of from 1 to 3 carbon atoms and R is STR2 wherein n is an integer which is at least 1, and the or each Q substituent, which when n is greater than 1 may be the same or different, is selected from a saturated alkyl group of from 1 to 4 carbon atoms or an unsaturated alkyl group of from 2 to 4 carbon atoms, with the proviso that when A is unsaturated Q may also be selected from alkoxy of from 1 to 4 carbon atoms; halo; trihalomethyl; hydroxy; carboxyl; a salt of such a carboxyl group; carboalkyloxy; carboaryloxy; carboarylalkyloxy; --NR6 R7 or --CONR6 R7 ; in which R6 and R7 may be the same or different and are hydrogen or alkyl of from 1 to 4 carbon atoms; the 1-substituted-imidazole being the free base or an acid addition salt thereof. Methods of preparing the 1-substituted-imidazoles are also provided. The imidazoles have pharmacological properties that make them of use in the treatment of thromboembolic disorders, shock and angina pectoris.
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