A stereodivergent synthesis of five-membered N-heterocycles, such as 2,3-dihydropyrroles, and 2-methylene and 3-methylene pyrrolidines, has been developed through a tandem annulation of amino alkynes with diazo compounds and involves the trapping of in situ formed intermediates. Mechanistic investigations indicate that the copper-catalyzed tandem annulations proceed by allenoate formation and subsequent intramolecular hydroamination. In contrast, the rhodium-catalyzed protocol features a carbenoid insertion into the NH bond and subsequent Conia-ene cyclization.

A stereodivergent synthesis of five‐membered N‐heterocycles, such as 2,3‐dihydropyrroles, and 2‐methylene and 3‐methylene pyrrolidines, has been developed through a tandem annulation of amino alkynes with diazo compounds and involves the trapping of in situ formed intermediates. Mechanistic investigations indicate that the copper‐catalyzed tandem annulations proceed by allenoate formation and subsequent intramolecular hydroamination. In contrast, the rhodium‐catalyzed protocol features a carbenoid insertion into the NH bond and subsequent Conia‐ene cyclization.

We report here an effective protocol to prepare highly functionalized dihydropyrans via sequential reaction of cross-coupling-intramolecular Michael addition of functionalized terminal alkynes and diazo compounds under mild reaction conditions. Importantly, by choosing different ligands, the configuration of exocyclic double bonds of dihydropyrans can be selectively controlled.

A novel approach toward diverse six-membered carbo-/heterocycles has been developed using diazo compounds and alkyne-substituted malonates as the suitable substrates. The polyfunctionalized cyclohexenes, tetrahydropyridines, and dihydropyrans have been prepared in moderate to high yield under mild reaction conditions. Importantly, the ligand plays a significant role in this copper-catalyzed protocol.