Sc(OTf)3-promoted formal insertion of 4-diazo-1,4-dihydroisoquinoli-n-3-ones into C-H bond of 1,3-dicarbonyl compounds: Synthesis of 2-(3-oxo-1,2,3,4-tetrahydroisoquinolin-4-yl)-1,3-diarylpropane-1,3-diones

A facile and efficient synthesis of novel 2-(1,2,3,4-tetrahydroisoquinolin-4-yl)-1,3-diarylpropane-1,3-diones via the Sc(OTf)3-promoted reaction between 4-diazo-1,4-dihydroisoquinolin-3-ones and 1,3-dicarbonyl compounds is reported. This formal C-H bond insertion involves an activation of 1,3-dicarbonyl compounds with generation of triflic acid by-product, a formation of diazonium intermediate from diazo component by triflic acid promotion, and a subsequent intermolecular nucleophilic substitution step. Readily available starting materials, cheap catalyst, broad substrate scope (22 examples, up to 92% yield), and mild reaction conditions are the merits of this reaction.