Radical-mediated synthesis of 3,4-dihydroisocoumarins: total synthesis of hydrangenol

A radically promoted synthesis of 3,4-dihydroisocoumarins has been achieved in moderate to good yields using titanocene(III) chloride (Cp2TiCl) as the radical initiator. The total synthesis of (+/-)-hydrangenol has been completed using this radical technology. Cp2TiCl was prepared in situ from commercially available titanocene dichloride (Cp2TiCl2) and Zn-dust in THF under argon. (c) 2007 Elsevier Ltd. All rights reserved.