(-)-tert-butyldimethylsilyl (1R,3S,6R)-6-ethynyl-1,5,5-trimethyl-7-oxabicyclo[4.1.0]heptan-3-yl ether

2,2-Dimethyl-propionic acid (1R,3S,6R)-6-(3-hydroxy-but-1-ynyl)-1,5,5-trimethyl-7-oxa-bicyclo[4.1.0]hept-3-yl ester

Toluene-4-sulfonic acid (1R,3S,6R)-6-ethynyl-1,5,5-trimethyl-7-oxa-bicyclo[4.1.0]hept-3-yl ester