An efficient and general method for the synthesis of 2-alkynyltetrahydrofuran was developed. The regioselective functionalization of the C(sp(3))-H bond adjacent to an oxygen atom with various alkynyl bromides has been achieved under transition-metal-free reaction conditions. Sodium fluoride was found, for the first time, to promote the efficient functionalization process remarkably. Moreover, 1,2-dibromostyrenes were also found to be effective in this method forming 2-alkenyltetrahydrofurans.
Gold- or Indium-Catalyzed Cross-Coupling of Bromoalkynes with Allylsilanes through a Concealed Rearrangement
作者:M. Elena de Orbe、Margherita Zanini、Ophélie Quinonero、Antonio M. Echavarren
DOI:10.1021/acscatal.9b02314
日期:2019.9.6
The gold(I)-catalyzed reaction of bromoalkynes with allylsilanes gives 1,4-enynes in a formal cross-coupling reaction. Mechanistic studies revealed the involvement of gold(I) vinylidenes or vinylidenephenonium gold(I) cations depending on the substituent on the bromoalkyne. In the case of bromo arylalkynes, the vinylidenephenonium gold(I) cations lead to 1,4-enynes via a 1,2-aryl rearrangement. The same reactivity has been observed in the presence of InBr3.