Regio- and Stereoselective 1,2-Carboboration of Ynamides with Aryldichloroboranes

Catalyst-free 1,2-carboboration of ynamides is presented. Readily available aryldichloroboranes react with alkyl- or aryl-substituted ynamides in high yields with complete regio- and stereoselectivity to valuable beta-boryl-beta-alkyl/aryl alpha-aryl substituted enamides which belong to the class of trisubstituted alkenylboronates. The 1,2-carboboration reaction is experimentally easy to conduct, shows high functional group tolerance and broad substrate scope. Gram-scale reactions and diverse synthetic transformations convincingly demonstrate the synthetic potential of this method. The reaction can also be used to access 1-boraphenalenes, a class of boron-doped polycyclic aromatic hydrocarbons.

Automated summary

The study introduces a catalyst-free 1,2-carboboration reaction of ynamides, which shows high yields with complete regio- and stereoselectivity, yielding valuable enamide compounds with synthetic potential.