3 research outputs found
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
Synthesis of Functionalized 1<i>H</i>‑Indenes and Benzofulvenes through Iodocyclization of <i>o</i>‑(Alkynyl)styrenes
A convenient
method for the preparation of synthetically useful
3-iodoindene derivatives has been developed. This protocol, based
on the 5-endo iodocyclization reaction of <i>o</i>-(alkynyl)styrenes,
represents one of the scarce examples of halocyclizations using olefins
as nucleophilic counterparts and allows the synthesis of both 3-iodo-1<i>H</i>-indenes (from β-alkyl-β-alkyl/aryl-<i>o</i>-(alkynyl)styrenes) and 3-iodobenzofulvenes (from β,β-diaryl-<i>o</i>-(alkynyl)styrenes) in good yields under mild reaction
conditions. In addition, related alkoxyiodocyclization processes are
described, which are particularly interesting in their intramolecular
version because they allow the synthesis of heteropolycyclic structures
containing the indene core. Finally, the usefulness of the prepared
3-iodoindenes has been demonstrated by the synthesis of several polysubstituted
indene derivatives through conventional palladium-catalyzed cross-coupling
reactions and iodine–lithium exchange processes