An organocatalytic asymmetric Nazarov cyclization.
An organocatalytic asymmetric Nazarov cyclization of diketoesters that proceeds by means of a dual activation mechanism has been developed. Screening of a number of catalysts led to a new thiourea that incorporates a primary amino group. The method gives rise to cyclic products with two adjacent quaternary asymmetric carbon atoms, one of which is an all-carbon stereocenter, with complete or nearly complete diastereoselectivity and in high or very high enantiomeric excess. A brief and very convenient synthesis of the acyclic diketoester starting materials through nucleophilic addition to a ketene is also described.
Basak
Ashok K
AK
Department of Chemistry, 2545 The Mall, University of Hawaii, Honolulu, Hawaii 96822, USA.
Shimada
Naoyuki
N
Bow
William F
WF
Vicic
David A
DA
Tius
Marcus A
MA
D002384:Catalysis; D003500:Cyclization; D004952:Esters; D009930:Organic Chemicals / Q000737:chemistry*
D004952:Esters; D009930:Organic Chemicals