Heteropoly acid catalysts in the valorization of the essential oils: Acetoxylation of β-caryophyllene

H 3 PW 12 O 40 (PW), the strongest heteropoly acid in the Keggin series, is an active and environmentally friendly catalyst for the liquid-phase conversion of β -caryophyllene ( 1 ) to β -caryolanyl acetate ( 2 ) in homogeneous and heterogeneous systems. An efficient and clean method for the synthesis of 2 , providing a mixture containing two stereoisomeric β -caryolanyl acetates 2a and 2b , 2a/2b = 80/20 mol/mol, with 100% GC yield, has been developed using PW as a homogeneous catalyst under mild reaction conditions. The reaction occurs at 25 °C with a catalyst turnover number of 2000. The catalyst can be recovered without neutralization and reused without loss of activity and selectivity.