Et₂Zn-Mediated Gem-Dicarboxylation of Cyclopropanols with CO₂

An unprecedented Et2Zn-mediated gem-dicarboxylation of C-C/C-H single bond of cyclopropanols with CO2 is disclosed, which provides a straightforward and efficient methodology for the synthesis of a variety of structurally diverse and useful malonic acids in moderate to excellent yields. The protocol features mild reaction conditions, excellent functional group compatibility, broad substrate scope, and facile derivatization of the products. DFT calculations confirm that the transition-metal-free transformation proceeds through a novel ring-opening/alpha-functionalization/ring-closing/ring-opening/beta-functionalization (ROFCOF) process, and 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) plays dual important roles in the transformation.