[(S)-1-Ethyl-3-oxo-3-((1R,2R,4R)-1,7,7-trimethyl-2-trimethylsilanyloxy-bicyclo[2.2.1]hept-2-yl)-propyl]-carbamic acid benzyl ester
{(R)-2-Methyl-1-[2-oxo-2-((1R,2R,4R)-1,7,7-trimethyl-2-trimethylsilanyloxy-bicyclo[2.2.1]hept-2-yl)-ethyl]-propyl}-carbamic acid benzyl ester
{(S)-1-[2-Oxo-2-((1R,2R,4R)-1,7,7-trimethyl-2-trimethylsilanyloxy-bicyclo[2.2.1]hept-2-yl)-ethyl]-butyl}-carbamic acid benzyl ester
{(S)-1-[2-Oxo-2-((1R,2R,4R)-1,7,7-trimethyl-2-trimethylsilanyloxy-bicyclo[2.2.1]hept-2-yl)-ethyl]-pentyl}-carbamic acid benzyl ester
[(R)-1-Cyclohexyl-3-oxo-3-((1R,2R,4R)-1,7,7-trimethyl-2-trimethylsilanyloxy-bicyclo[2.2.1]hept-2-yl)-propyl]-carbamic acid benzyl ester