Polar Intramolecular Cross-Cycloadditions of Cyclopropanes toward Natural Product Synthesis

In this account we have systematically described the acid-promoted intramolecular cycloadditions of activated cyclopropanes, which were conceptually classified into intramolecular cross-cycloadditions (IMCC) and intramolecular parallel-cycloadditions. The IMCC provided a general and efficient strategy for construction of structurally complex and diverse bridged bicyclic skeletons. The potential of this strategy has been demonstrated by the synthesis of natural products.