Efficient route to 4a-methyltetrahydrofluorenes:: A total synthesis of (±)-dichroanal B via intramolecular Heck reaction

An efficient new route based on intramolecular Heck cyclization of the diene 11 was developed to prepare the 4a-methyltetrahydrofluorene diterpenoids and utilized for the total synthesis of (+/-)-dichroanal B with Significantly improved overall yield.