Indium(III) triflate-catalysed [4 + 2] benzannulation reactions of o-alkynylbenzaldehydes with enolisable carbonyl compounds: selective synthesis of naphthyl ketones.
Indium(III) triflate is found to be an effective catalyst for the benzannulation reactions of o-alkynylbenzaldehydes with enolisable aldehydes, ketones, 1,3-diketones and β-keto esters. The reactions produce naphthyl ketones through ring opening of adducts arising from the inverse electron demand Diels-Alder reactions between in situ generated isochromenylium cations and enols. The main feature of the method is selective formation of naphthyl ketones in a highly regioselective manner without any decarbonylation.
School of Chemistry, Bharathidasan University, Tiruchirapalli 620 024, Tamil Nadu, India. srinivasank@bdu.ac.in.
Karuppusamy
K
Sakthivel
Kannupal
K
Srinivasan
D000480:Alkynes / Q000737:chemistry*; D001547:Benzaldehydes / Q000737:chemistry*; D002384:Catalysis; D003500:Cyclization; D007659:Ketones / Q000138:chemical synthesis* / Q000737:chemistry; D008698:Mesylates / Q000737:chemistry*; D015394:Molecular Structure
D000480:Alkynes; D001547:Benzaldehydes; D007659:Ketones; D008698:Mesylates; C012077:trifluoromethanesulfonic acid