- Controlling Selectivity by Controlling the Path of Trajectories
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Consideration of the role of dynamic trajectories in [1,2]- and [2,3]-sigmatropic rearrangements suggests a counterintuitive approach to controlling the selectivity. In our hypothesis, [2,3] selectivity can be promoted by reaction conditions that thermodynamically disfavor the [2,3] rearrangement step and thereby make the transition state later. The application of this idea has led to a successful prescription for dictating the selectivity in Stevens/Sommelet-Hauser rearrangements of ammonium ylides. A combination of kinetic isotope effects, crossover experiments, and computational dynamic trajectories support the idea that the selectivity is controlled through control of the path of trajectories.
- Biswas, Bibaswan,Singleton, Daniel A.
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supporting information
p. 14244 - 14247
(2015/12/01)
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- Novel isomerization reaction of N,N-dimethyl-α-(methoxycarbonyl)-4- substituted-benzylammonium N-methylides
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Fluoride ion-induced desilylation of N,N-dimethyl-N- [(trimethylsilyl)methyl]-α-(methoxycarbonyl)4-substituted benzylammonium salts (7) gave two Stevens rearrangement products: methyl 3-(dimethylamino)- 2-(4-substituted phenyl)propionates (13) from N-methylides 8, and methyl 3- (dimethylamino)-3-(4-substituted phenyl)propionates (15) from N-benzylides 10. Additional Stevens rearrangement products, methyl 2-(dimethylamino)-3- (4-substituted phenyl)propionates (16), were competitively formed from ylides 12 when the cesium fluoride used was not predried. The mechanism of the isomerization from methylides 8, which was initially generated, to 10 and 12 is discussed.
- Zhang, Chen,Ito, Hiroto,Maeda, Yasuhiro,Shirai, Naohiro,Ikeda, Shin-Ichi,Sato, Yoshiro
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p. 581 - 586
(2007/10/03)
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