Dual 1,3-dipolar cycloaddition of carbon dioxide: two C=O bonds of CO2 react in one reaction.

The first investigation into two C[double bond, length as m-dash]O bonds of CO2 reacting in one reaction through dual 1,3-dipolar cycloaddition of CO2 with isocyanides and dialkyl acetylenedicarboxylates has been reported. The reaction proceeded efficiently at 80 °C at a pressure of 1 atm of CO2, affording symmetric 1,6-dioxospiro[4,4]nonane-3,8-diene derivatives in moderate yields.