Synthesis of Allylboranes via Cu(I)-Catalyzed B–H Insertion of Vinyldiazoacetates into Phosphine–Borane Adducts
作者:Denis Drikermann、Robert S. Mößel、Walid K. Al-Jammal、Ivan Vilotijevic
DOI:10.1021/acs.orglett.9b04619
日期:2020.2.7
Cu(I) catalysts enable C-B bond formation via direct insertion of vinyldiazoacetates into B-H bonds of borane-phosphine Lewis adducts to form phosphine-protected allylboranes under mild conditions. The resulting allylborane-phosphine Lewis adducts can be used in the diastereoselective allylation of aldehydes directly without the need for removal of the phosphine. The allylation reaction proceeds with
Vinyldiazo compounds undergo a thermal electrocyclization to form pyrazoles in yields of up to 95%. The reactions are operationally simple, use readily available starting materials, require no intervention of a catalyst, and enable the synthesis of mono-, di- and tri-substituted pyrazoles. With the ability to produce highly substituted pyrazoles and the flexibility in installing various types of substituents