Enantioselective thiourea-catalyzed cationic polycyclizations.
A new thiourea catalyst is reported for the enantioselective cationic polycyclization of hydroxylactams. Both the yield and enantioselectivity of this transformation were found to vary strongly with the identity of a single aromatic residue on a common catalyst framework, with more expansive and polarizable arenes proving optimal. Evidence is presented for a mechanism in which stabilizing cation-pi interactions are a principal determinant of enantioselectivity.
Knowles
Robert R
RR
Department of Chemistry & Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Lin
Song
S
Jacobsen
Eric N
EN
D002384:Catalysis; D002412:Cations / Q000138:chemical synthesis / Q000737:chemistry; D003500:Cyclization; D007769:Lactams / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D013237:Stereoisomerism; D013890:Thiourea / Q000737:chemistry*
D002412:Cations; D007769:Lactams; D013890:Thiourea