An efficient catalytic system for cyclocarbonylation of terpenes into lactones

Abstract

Three different kinds of representative monoterpenic alcohol are involved in the palladium-catalysed cyclocarbonylation reaction. Lactone formation is shown to occur when cyclic (1), tertiary (3) and primary allylic alcohol (7) functions are reacted, in the presence of CO with [HPd(SnCl3)L2] as the active catalytic species. Good yields and selectivities can easily be reached for isopulegol (1), and dihydromyrcenol (3). However, more modest results are obtained for the functionalization of geraniol into the original lactone (9). This lactone can be largely favoured by using a basic chelating diphosphine ligand such as 1,4-bis(diphenylphosphino)butane. Copyright © 2005 John Wiley & Sons, Ltd.