Formation of C(sp2)-Boronate Esters by Borylative Cyclization of Alkynes Using BCl3

BCl3 is an inexpensive electrophile which induces the borylative cyclization of a wide range of substituted alkynes to regioselectively form polycycles containing synthetically versatile C(sp(2))-boronate esters. It proceeds rapidly, with good yields and is compatible with a range of functional groups and substitution patterns. Intermolecular 1,2-carboboration of alkynes is also achieved using BCl3 to generate trisubstituted vinyl boronate esters.