Synthesis of N ‐Heterocycles via [3 + n] Cycloaddition Reactions of Vinyl Metal Carbene Intermediates

Recently, the vinyl metal carbene species, which possesses vinylogous and carbene reactivities, has been proved to be a templated 3-C building block for [3+n]-cycloadditions reactions, allowing expeditious construction of various cyclic farmworkers, especially for the N-heterocycles with different ring-sizes and molecular diversity. Although reviews that focused on the unique reagent or specific transformation have been reported in the past decade for the cycloadditions of metal carbene intermediates, this chapter focuses on the advances of using vinyl metal carbene species as a 3-C synthon for the expeditious construction of N-heterocycles with structural diversity through a variety of [3+n]-cycloaddition reactions. Catalytic carbene/alkyne metathesis with readily available carbene precursors and alkynes has provides an effective approach for the in situ generation of vinyl carbene intermediates, which is difficult to directly access with other carbene precursors.