- 1,3-dioxolan-2-ylium cations from acylfurans: Conversion of furyl ketones to esters under nonoxidative conditions
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Acylfurans 3 furnished tosylated glycol monoesters 5 when treated with 1,2-diols in the presence of an equivalent of TsOH. This process likely occurs via protiodefuranation of the intermediate furyl ketals to form 1,3- dioxolan-2-ylium cations 8. Subsequent ring-opening via S(N)2 nucleophilic displacement by p-toluenesulfonate then provides esters 5. When a 1,3-diol was employed, furancontaining ester 9 was formed instead of the standard product through an apparent aldol dimerization/fragmentation pathway.
- Bender, John A.,Daves, Samantha,West
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p. 2051 - 2054
(2007/10/03)
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- Deacylation of Pyrrole and other Aromatic Ketones
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Ethyl 4-acetyl-3,5-dimethyl-1H-pyrrole-2-carboxylate (1a) reacts rapidly with ethylene glycol in refluxing benzene with p-toluenesulfonic acid or perchloric acid as a catalyst to give ethyl 3,5-dimethyl-1H-pyrrole-2-carboxylate (3) in high yield (96 percent).Various 2- and 3-acylpyrroles can be efficiently deacylated by using this procedure.Other ketones which undergo deacylation include phenyl(2-phenylindol-3-yl)methanone (19), 1-(5-methyl-1-phenylpyrazol-4-yl)ethanone (20), and 2,4-dimethoxybenzophenone.Certain pyrrole ketones where the acyl group is flanked by two ring methyl groups are also cleaved under acidic conditions by using ethanedithiol.
- Moon, M. W.,Wade, R. A.
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p. 2663 - 2669
(2007/10/02)
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