- Ynamide-Mediated Thionoester and Dithioester Syntheses
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A novel ynamide-mediated synthesis of thionoesters and dithioesters is described. The selective addition reactions of various monothiocarboxylic acids with ynamide furnish α-thioacyloxyenamides, which undergo transesterification with nucleophilic -OH or -SH species to afford thionoesters and dithioesters, respectively. The broad substrate scope, mild reaction conditions, and excellent yields make this method an attractive synthetic approach to thionoesters and dithioesters.
- Yao, Chaochao,Yang, Jinhua,Lu, Xiaobiao,Zhang, Shuyu,Zhao, Junfeng
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- Kinetics and mechanism of the aminolysis of phenyl dithiobenzoates
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The kinetics and mechanism of the reactions of phenyl dithiobenzoates with anilines in acetonitrile at 55.0 deg C have been studied.The large magnitude of βx(βnuc) and the signs of cross-interaction constants, ρeXY > 0, ρYZ XZ > 0, are all consistent with the carbonyl addition mechanism in which the breakdown of the tetrahedral intermediate, T+/-, is rate limiting.The thiocarbonyl group (C=S) is found to favour amine expulsion in contrast to the carbonyl group (C=O) which favours the S-bonded nucleofuge expulsion from T+/-.The signs of cross-interaction constants, ρXY, ρYZ and/or ρXZ, are shown to provide useful mechanistic criteria for distinguishing, especially, the carbonyl addition mechanism involving the rate-limiting breakdown of the tetrahedral intermediate (T+/- from the concerted SN2 mechanism.
- Oh, Hyuck Keun,Shin, Chul Ho,Lee, Ikchoon
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p. 1169 - 1174
(2007/10/02)
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