Selective monoterpene-like cyclization reactions achieved by water exclusion from reactive intermediates in a supramolecular catalyst.
A polyanionic supramolecular assembly (1) is shown to catalytically cyclize the monoterpene citronellal and two homologues. In contrast to cyclization in acidic aqueous solution, the hydrophobic interior of 1 prevents the capture of reactive intermediates by water. This effect was also observed in the gold-catalyzed cycloisomerization of an enyne. Due to the steric confinement of the catalyst's interior, Prins cyclizations in 1 proceed cleanly both for substrates containing and lacking gem-dimethyl substitution. Encapsulation in 1 consequently imposes a degree of mechanistic control that, similar to enzyme catalysis, is not observed in bulk aqueous solution.
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
William M
WM
Hart-Cooper
Kristen N
KN
Clary
F Dean
FD
Toste
Robert G
RG
Bergman
Kenneth N
KN
Raymond
D000438:Alcohols / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003500:Cyclization; D046911:Macromolecular Substances / Q000737:chemistry; D015394:Molecular Structure; D014867:Water / Q000737:chemistry*
D000438:Alcohols; D046911:Macromolecular Substances; D014867:Water