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.1 Introduction2 [3+2]IMCC of Cyclopropane 1,1-Diester with C=O3 [3+2]IMCC of Cyclopropane 1,1-Diester with C=N4 [3+2]IMCC of Cyclopropane 1,1-Diester with C=C5 [3+3]IMCC of Cyclopropane 1,1-Diester with Nitrones6 [3+2]IMCC of Mono-donor/Mono-acceptor Cyclopropane with C=O7 Lewis Acid Regulated Domino Cycloisomerization/[4+2]IMCC or [3+2]IMCC of Alkynylcyclopropane Ketone with C=O and C=N8 Conclusions and Outlook [ABSTRACT FROM AUTHOR]