Synthesis of 2-substituted 7-hydroxybenzofuran-4-carboxylates via addition of silyl enol ethers to o-benzoquinone esters.
Mukaiyama Michael addition of silyl enol ethers 13 to the 1,2-quinone-4-carboxylate 6 (formed in situ by oxidation of the catechol ester 8) afforded the 2-subsituted 7-hydroxybenzofuran-4-carboxylates 14 in fair to good yields. Alkyl and aryl systems work well, but highly electron-rich silyl enol ethers could not be used because of competing oxidation.
Jung
Michael E
ME
Department of Chemistry and Biochemistry, University of California, Los Angeles, 405 Hilgard Avenue, Los Angeles, California 90095, USA. jung@chem.ucla.edu
Perez
Felix
F
D001572:Benzofurans / Q000138:chemical synthesis* / Q000737:chemistry; D016227:Benzoquinones / Q000737:chemistry*; D002264:Carboxylic Acids / Q000138:chemical synthesis*; D002384:Catalysis; D003500:Cyclization; D004952:Esters; D004987:Ethers / Q000737:chemistry*; D015394:Molecular Structure; D010084:Oxidation-Reduction; D012821:Silanes / Q000737:chemistry*
D001572:Benzofurans; D016227:Benzoquinones; D002264:Carboxylic Acids; D004952:Esters; D004987:Ethers; D012821:Silanes; C025225:2-benzoquinone