- BH3-catalyzed oligomerization of ethyl diazoacetate: The role of C-boron enolates
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In contrast to trialkyl boranes, the reaction of borane (BH3) and ethyl diazoacetate (EDA) generates dimer, trimer, and oligomers of EDA. The products arise from double, triple, and multiple insertions of CHCO 2Et groups in B-C bonds. On the basis of NMR spectroscopic data, trapping experiments, and computational studies, a novel C-boron enolate has been identified as a key intermediate in this reaction. This C-boron enolate species is calculated to be 7.1 kcal/mol (gas phase) more stable than its isomeric O-boron enolate form. Both spectroscopic data and trapping results also reveal the formation of a doubly borylated enolate generated as a side product by a proton transfer between the C- and O-boron monoenolates.
- Bai, Jie,Burke, Lonnie D.,Shea, Kenneth J.
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- Improved synthesis of trifluoromethyl sulfones used as intermediates for the preparation of di- or tri-substituted olefins
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Primary and secondary trifluoromethyl sulfones (triflones) are efficiently obtained from easily available sodium trifluoromethanesulfinate (triflinate) and alkyl bromides in N,N-dimethylacetamide.This technique is more powerful than the potassium triflinate/acetonitrile system.Ethyl aconitate can be also produced in one step from ethyl bromoacetate and diisopropylethylamine, sodium triflinate being a catalyst.
- Eugene, Fabrice,Langlois, Bernard,Laurent, Eliane
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p. 301 - 310
(2007/10/02)
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