Diastereoselective Rhodium Catalyzed [4+2] Cycloisomerization of Allenes

A diastereoselective [4 + 2] cycloisomerization of asymmetric allenyl dienes is reported. The asymmetric dienyl allenes are synthesized using the method reported by Ma. These substrates readily undergo diastereoselective intramolecular rhodium catalyzed [4 + 2] cycloisomerization analogous to thermal intramolecular Diels-Alder reactions. Overall, 29 examples are presented with tethers possessing nitrogen, oxygen, and carbon. Diastereoselectivities range from 99:1 to 90:10 in most examples.

Automated summary

This study reports a diastereoselective [4 + 2] cycloisomerization of asymmetric allenyl dienes synthesized using Ma's method. These substrates undergo diastereoselective intramolecular rhodium catalyzed [4 + 2] cycloisomerization similar to thermal intramolecular Diels-Alder reactions, with diastereoselectivities ranging from 99:1 to 90:10 in most examples out of 29 presented.