ENANTIOEXCESS MONOTERPENES FROM ROOTS OF ASIASARUM-SIEBOLDI

Three new monoterpenes, named (+)-asarinol C, (-)-asarinol C and (+)-asarinol D have been isolated from the roots of Asiasarum sieboldi, along with a known compound, trans-4-hydroxy-5-(1-hydroxy-l-methylethyl)-2-methyl-2-cyclohexen-1-one. On the basis of spectral analyses including X-ray crystallographic analysis, the structures of (+)-asarinol C, (-)-asarinol C and (+)-asarinol D have been established as (+)-(1R,5S)-5-hydroxy-4,7,7-trimethyl-8-oxabicyclo[3,21]-hept-3-en-2-one, (-)-(1S,5R)-5-hydroxy-4,7,7-trimethyl-8-oxabicyclo[3.2.1]-hept-3-en-2-one and (+)-(4S,5S)-4,5-dihydroxy-2,6,6-trimethyl-2-cyclohepten-1-one, respectively. The optical resolution of the above compounds suggested that these compounds were enantioexcess monoterpenes.