Enantioselective Synthesis of 5,7-Bicyclic Ring Systems from Axially Chiral Allenes Using a Rh(I)-Catalyzed Cyclocarbonylation Reaction

A transfer of chirality in an intramolecular
Rh­(I)-catalyzed allenic Pauson–Khand reaction (APKR) to access
tetrahydroazulenones, tetrahydrocyclopenta­[c]­azepinones
and dihydrocyclopenta­[c]­oxepinones enantioselectively
(22–99% ee) is described. The substitution pattern of the allene
affected the transfer of chiral information. Complete transfer of
chirality was obtained for all trisubstituted allenes, but loss of
chiral information was observed for disubstituted allenes. This work
constitutes the first demonstration of a transfer of chiral information
from an allene to the 5-position of a cyclopentenone using a cyclocarbonylation
reaction. The absolute configuration of the corresponding cyclocarbonylation
product was also established, something that is rarely done.