Synthesis of coumarins, 4-hydroxycoumarins, and 4-hydroxyquinolinones by tellurium-triggered cyclizations.
Coumarins, 4-hydroxycoumarins, and 4-hydroxyquinolin-2(1H)-ones can be conveniently prepared by treatment of alpha-halocarboxylic acid esters of salicylaldehyde, o-hydroxyacetophenone, methyl salicylate, and methyl N-methyl- or N-phenylanthranilates with sodium or lithium telluride. Phenylketene formation competes with cyclization of the alpha-chlorophenylacetate ester of methyl salicylate as demonstrated by a trapping experiment with benzylamine. Elemental tellurium may be recovered and reused.
Dittmer
Donald C
DC
Department of Chemistry, Syracuse University, Room 1-014 CST, Syracuse, New York 13244, USA. dcdittme@syr.edu
Li
Qun
Q
Avilov
Dimitry V
DV
D002384:Catalysis; D003374:Coumarins / Q000138:chemical synthesis*; D003500:Cyclization; D006912:Hydroxyquinolines / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D015394:Molecular Structure; D013691:Tellurium / Q000737:chemistry*
D003374:Coumarins; D006912:Hydroxyquinolines; D007202:Indicators and Reagents; D013691:Tellurium