This review deals with the application of Lewis super acids such as Al(III), In(III), and Sn(IV) triflates and triflimidates as catalysts in the synthesis of fragrance materials. Novel catalytic reactions involving C-C and C-heteroatom bond-forming reactions, as well as cycloisomerization processes are presented. In particular, Sn(IV) and Al(III) triflates were employed as catalysts in the selective cyclization of unsaturated alcohols to cyclic ethers, as well as in the cyclization of unsaturated carboxylic acids to lactones. The addition of thiols and thioacids to non-activated olefins, both in intra- and intermolecular versions, was efficiently catalyzed by In(III) derivatives. Sn(IV) Triflimidates catalyzed the cycloisomerization of highly substituted 1,6-dienes to gem-dimethyl-substituted cyclohexanes bearing an isopropylidene substituent. The hydroformylation of these unsaturated substrates, catalyzed by a Rh(I) complex with a bulky phosphite ligand, selectively afforded the corresponding linear aldehydes. The olfactory evaluation of selected heterocycles, carbocycles, and aldehydes synthesized is also discussed.

A new tandem isomerisation/cyclisation of α-methallyloxy carboxylic acids leading to substituted 1,3-dioxolan-4-ones in 60-70 % yields was catalysed by Cu(OTf) 2 or Al(OTf) 3 . Extension to the synthesis of oxathiolanones and oxathianones is also described.

InIII triflate-catalysed addition of thiols and thiocarboxylic acids to camphene under mild conditions has allowed the functionalisation of the alkene for the first time, with suppression of the classical rearrangement of the camphene terpene skeleton to isobornane structures.