Enantioselective TADMAP-catalyzed carboxyl migration reactions for the synthesis of stereogenic quaternary carbon.
The chiral, nucleophilic catalyst TADMAP [1, 3-(2,2,2-triphenyl-1-acetoxyethyl)-4-(dimethylamino)pyridine] has been prepared from 3-lithio-4-(dimethylamino)pyridine (5) and triphenylacetaldehyde (3), followed by acylation and resolution. TADMAP catalyzes the carboxyl migration of oxazolyl, furanyl, and benzofuranyl enol carbonates with good to excellent levels of enantioselection. The oxazole reactions are especially efficient and are used to prepare chiral lactams (23) and lactones (30) containing a quaternary asymmetric carbon. TADMAP-catalyzed carboxyl migrations in the indole series are relatively slow and proceed with inconsistent enantioselectivity. Modeling studies (B3LYP/6-31G*) have been used in qualitative correlations of catalyst conformation, reactivity, and enantioselectivity.
Shaw
Scott A
SA
Department of Chemistry, University of Michigan, Ann Arbor, Michigan 48109, USA.
Aleman
Pedro
P
Christy
Justin
J
Kampf
Jeff W
JW
Va
Porino
P
Vedejs
Edwin
E
D015761:4-Aminopyridine / Q000031:analogs & derivatives* / Q000737:chemistry; D000447:Aldehydes / Q000737:chemistry*; D002264:Carboxylic Acids / Q000737:chemistry*; D002384:Catalysis; D005663:Furans / Q000737:chemistry; D007769:Lactams / Q000138:chemical synthesis*; D007783:Lactones / Q000138:chemical synthesis*; D008958:Models, Molecular; D008968:Molecular Conformation; D010080:Oxazoles / Q000737:chemistry; D013237:Stereoisomerism; D013816:Thermodynamics
D000447:Aldehydes; D002264:Carboxylic Acids; D005663:Furans; D007769:Lactams; D007783:Lactones; D010080:Oxazoles; D015761:4-Aminopyridine; C003885:4-dimethylaminopyridine