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A method for the stereoselective [4+2]‐cycloaddition of alkenylboranes and dienes is presented. This transformation was accomplished through the introduction of a new strategy that involves the use of chiral N‐protonated alkenyl oxazaborolidines as dieneophiles. The reaction leads to the formation of products that can be readily derivatized to more complex structural motifs through stereospecific transformations of the C−B bond such as oxidation and homologation. Detailed computation evaluation of the reaction has uncovered a surprising role of the counterion on stereoselectivity.

The development of pyridylidene‐Cu‐complexes and their application in Cu/Pd‐catalyzed heteroarylboration of alkenylheteroarenes is reported. The significance of 1,1′‐heteroarylalkanes as building blocks for drug discovery, as well as the straightforward and modular sequence to prepare the pyridylidene‐Cu‐complexes, makes this catalyst and it applications attractive for chemical synthesis. Furthermore, chiral variants of the pyridylidene‐Cu‐complexes have been prepared and utilized in the enantioselective arylboration of E‐alkenes, further demonstrating the value and potential of this class of catalysts.