Synthetic studies on nemorosone via enantioselective intramolecular cyclopropanation

This Letter describes synthetic studies of nemorosone via enantioselective intramolecular cyclopropanation. For the total synthesis of nemorosone, three potential intermediates were evaluated through the efficiency of three sequential reactions, namely, their intramolecular cyclopropanation, dimethylation of the resultant cyclopropanes, and ring-opening reaction of the alkylated cyclopropanes. As a result, α-diazomethyl ketone 10c was found to be the most suitable. The enantioselective intramolecular cyclopropanation to construct the bicyclo[3.3.1]nonane core and preparation of the compound with all the correct stereogenic centers of nemorosone are also described.