- Efficient α-chlorination of carbonyl containing compounds under basic conditions using methyl chlorosulfate
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An efficient method for the α-chlorination of ketones under basic conditions is described using methyl chlorosulfate. Its applicability for the chlorination of other functional groups has also been studied and it is equally useful for the synthesis of α-chloroesters and amides. Methyl chlorosulfate is described for the first time as a positive chlorine source. Some aldol reactions which occur during the chlorination of some substrates are also reported.
- Silva, Saúl,Maycock, Christopher D.
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supporting information
p. 1233 - 1238
(2018/02/27)
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- Total regioselective and diastereospecific iodolysis of 2,3-epoxyamides promoted by SmI2: Synthesis of (2R*,3R*)- or (2R*,3S*)-2-hydroxy-3-iodoamides
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The use of samarium diiodide as a source of iodides is reported. Thus, 2-hydroxy-3-iodoamides were obtained, with total regioselectivity, by treatment of 2,3-epoxyamides, in which the oxirane ring is 2,3-disubstituted or 2,2,3-trisubstituted, with SmI2. The ring-opening reaction was diastereospecific and (2R*,3R*)- or (2R*,3S*)-2-hydroxy- 3-iodoamides were obtained from cis- or trans-epoxyamides, respectively. The relative configuration of 2-hydroxy-3-iodoamides was established by X-ray analysis. A mechanism to explain this transformation has been proposed. The starting compounds 1 are easily prepared by the reaction of enolates derived from 2-chloroamides with aldehydes at -78°C.
- Concellon, Jose M.,Bardales, Eva,Concellon, Carmen,Garcia-Granda, Santiago,Diaz, M. Rosario
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p. 6923 - 6926
(2007/10/03)
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- Evaluation of glycolamide esters and various other esters of aspirin as true aspirin prodrugs
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A series of glycolamide, glycolate, (acyloxy)methyl, alkyl, and aryl esters of acetylsalicylic acid (aspirin) were synthesized and evaluated as potential prodrug forms of aspirin. N,N-Disubstituted glycolamide esters were found to be rapidly hydrolized in human plasma, resulting in the formation of aspirin as well as the corresponding salicylate esters. These in turn hydrolyzed rapidly to salicylic acid. The largest amount of aspirin formed from the esters were 50 and 55% in case of the N,N-dimethyl- and N,N-diethylglycolamide esters, respectively. Similar results were obtained in blood with the N,N-dimethyl- and N,N-diethylglycolamide esters. Unsubstituted and monosubstituted glycolamide esters as well as most other esters previously suggested to be aspirin prodrugs were shown to hydrolyze exclusively to the corresponding salicylic acid esters. Lipophilicity parameters and water solubilities of the esters were determined, and structural factors favoring ester prodrug hydrolysis at the expense of deacetylation to yield salicylate ester are discussed. The properties of some N,N-disubstituted glycolamide esters of aspirin are highlighted with respect to their use as potential aspirin prodrugs.
- Nielsen,Bundgaard
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p. 727 - 734
(2007/10/02)
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- Process for production of α-haloalkylamides
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Amides having the formula in which R is α-halo-C1 -C8 -alkyl; R2 is C1 -C8 alkyl, and R3 is C1 -C8 alkyl, are prepared by reacting an ester with an amine in the presence of a promotor which is a halide of a Group IIIa metal having a molecular weight of 26 or greater, or of a Group IVb metal. The process is particularly suitable for production of a desired optical isomer of such an amide.
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