Reaction of Elemol with Acetic acid –Perchloric acid: Characterization of a novel oxide and (+)-β-cyperone

Abstract

The minor unidentified compounds of acetic acid- perchloric acid dehydration of elemol (1) have been fully characterized. The structure and relative stereochemistry as shown in (2) of the less polar fragrant compound named as elemoxide was deduced by 1D and 2D NMR data including carbon-carbon connectivity, NOE and NOESY experiments. The absolute stereochemistry was established as 3S,3aR,7aR-6-isopropyl-1,1,3,3a-tetramethyl 1,3,3a,4,7,7a hexahydro isobenzofuran (2) on the basis of its preparation from elemol 1.(+)-b-cyperone (3), a known sesquiterpene, has also been identified as a minor product of the reaction. Plausible mechanistic explanation for the formation of elemoxide (2) and (+)-b-cyperone (3) presented.