very rapid and efficient method has been developed for the synthesis of vicinal bromohydrins and alkoxybromides directly from an olefin without any catalyst. The reaction was performed in CH3CN−water (4:1) or alcohol using N,N-dibromo-p-toluenesulfonamide (TsNBr2) as the brominating agent. Excellent yields and regio- and stereoselectivities have been obtained. Bromohydrins are formed instantaneously
Generation of Interhalogen Fluorides under Mild Conditions: A Comparison of Sluggish and Reactive Interhalogen Fluorides
作者:Dale F. Shellhamer、Mark J. Horney、Benjamin J. Pettus、Tobiah L. Pettus、Joy Merry Stringer、Victor L. Heasley、Robert G. Syvret、John M. Dobrolsky
DOI:10.1021/jo972319g
日期:1999.2.1
Interhalogen fluorides (XF; X = I, Br, or Cl) generated from xenon difluoride (XeF2) or triethylamine trihydrofluoride (TREAT HF) with iodine (I-2), N-halosuccinimides (NXS; X = I, Br, or CI), or alkylhypohalites (ROX; R = CH3 or t-Bu, X = Br or Cl) with alkenes and aromatics are reported. A comparison of the above reactions with other methods reported in the literature to generate interhalogen fluorides is made. Interhalogens generated from direct action of elemental fluorine (F-2) or XF3 (X = I, Br, or Cl) with chlorine (Cl-2), bromine (Br-2), or iodine (I-2) give a species that can react with electron-deficient alkenes or aromatics. These reagents are too reactive for electron-rich substrates. Interhalogen fluorides from reagents like NXS or ROX with XeF2 or amine HF are much less reactive and give good yields with electron-rich akenes or aromatics.
Theoretical and infrared studies on the conformational isomerism of trans-2-bromo-alkoxycyclohexanes
作者:Josué M. Silla、Claudimar J. Duarte、Matheus P. Freitas、Teodorico C. Ramalho、Rodrigo A. Cormanich、Francisco P. Santos、Cláudio F. Tormena、Roberto Rittner
DOI:10.1016/j.saa.2011.06.023
日期:2011.10
The infraredspectra of trans-2-bromo-alkoxycyclohexanes (alcoxy = OMe, OEt, O(i)Pr and O(t)Bu) were obtained for the neat liquid, and the C-Br stretching mode was quantitatively analyzed to give insight about the conformational isomerism of these compounds. Frequency calculations supported the band assignments, and the relative band intensities suggest that the diaxial conformer is prevalent for the