Cyclopropylcarbinyl radicals as three-carbon insertion units: easy synthesis of C-15 macrocyclic ketones by three-carbon ring expansion

Thermal isomerization of cyclic 3-cyclopropyl ketones under FVP conditions at 620 °C provides a new and convenient route to δ,ε-unsaturated cycloalkanones. The synthetic potential of this novel three-carbon ring expansion has been demonstrated by the synthesis of (±)-muscone from inexpensive C-12 starting material.