Scalable Synthesis of the Amber Odorant 9-<i>epi</i>-Ambrox through a Biomimetic Cationic Cyclization/Nucleophilic Bromination Reaction

A novel biomimetic nucleophilic bromocyclization reaction is used in the key step of a new and straightforward synthesis of 9-<i>epi</i>-Ambrox, an organic compound of high interest and value in the context of fragrances. This strategic reaction allows access to 9-<i>epi</i>-Ambrox on a gram scale from a dienyne derivative, easily available from geraniol, following a sequence of seven steps (35% global yield) with just one purification process. Both enantiomers of the molecule were obtained by a challenging enzymatic resolution

Synthesis of Cyclohexanones through a Catalytic Cationic Cyclization of Alkynols or Enynes

A novel procedure for the synthesis of cyclohexanones from alkynol or enyne derivatives through a cationic cyclization has been developed. The key points to obtain the six-membered ring derivatives are the use of starting materials containing a terminal alkyne, the use of tetrafluoroboric acid as a promoter of the cationic cyclization, and the appropriate selection of 1,1,1,3,3,3-hexa­fluoro­propan-2-ol (HFIP) as solvent. This strategy can be extended to the biomimetic cationic cyclization of several terpene-derived polyenynes