200411-41-2Relevant academic research and scientific papers
Cyclisation versus 1,1-carboboration: Reactions of B(c6f 5)3 with propargyl amides
Melen, Rebecca L.,Hansmann, Max M.,Lough, Alan J.,Hashmi, A. Stephen K.,Stephan, Douglas W.
, p. 11928 - 11938 (2013/09/23)
A series of propargyl amides were prepared and their reactions with the Lewis acidic compound B(C6F5)3 were investigated. These reactions were shown to afford novel heterocycles under mild conditions. The reaction of a variety of N-substituted propargyl amides with B(C6F5)3 led to an intramolecular oxo-boration cyclisation reaction, which afforded the 5-alkylidene-4,5-dihydrooxazolium borate species. Secondary propargyl amides gave oxazoles in B(C 6F5)3 mediated (catalytic) cyclisation reactions. In the special case of disubstitution adjacent to the nitrogen atom, 1,1-carboboration is favoured as a result of the increased steric hindrance (1,3-allylic strain) in the 5-alkylidene-4,5-dihydrooxazolium borate species. Copyright
A hierarchy of aryloxide deprotection by boron tribromide
Punna, Sreenivas,Meunier, Stephane,Finn
, p. 2777 - 2779 (2007/10/03)
Aryl propargyl ethers and esters are cleaved selectively in the presence of aryl methyl ethers and esters by boron tribromide in dichloromethane. Under the same conditions, allyl ethers undergo very rapid Claisen rearrangement, and benzyl ethers are also cleaved more rapidly than propargyl. A mechanism involving intramolecular delivery of bromide to the propargyl terminus is proposed.
