SYNTHESIS OF MEDIUM AND LARGE RING COMPOUNDS .37. SYNTHESIS AND OLFACTORY PROPERTIES OF (Z)-5,6-DIMETHYLCYCLODODEC-5-EN-1-ONE AND (Z)-(+ -)-5,6-DIMETHYLCYCLODODEC-5-EN-1-OL/

According to molecular modelling calculations the title compound 13 sh ould fit the olfactory receptor of trans-10-ethyltetrahydroionol (1). In order to check this prediction the target molecule 13 and ketone 12 have been synthesized by starting from cyclooctyne and furan. Cleavag e of the oxanorbornene bridge of the selectively hydrogenated Diels-Al der adduct 5 with LTBAH/triethylborane, oxidation, epoxidation and alp ha,beta-epoxyketone --> alkynone fragmentation result in a ring enlarg ement of cyclooctyne by an oxotetramethylene unit. Key reaction is the diboration of cycloalkynone 9 followed by a Suzuki coupling with iodo methane. Reduction of ketone 12 gives the desired dimethylcyclododecen ol 13, which possesses only a weak cedarwood note. In contrast, the co rresponding ketone 12 has an intensive odor described as dry, cedarwoo d-like with interesting cooling animal facets.