Ketones undergo a smooth addition to N-acylisoquinolinium ions in N-methyl-2-pyrrolidinone, under mild conditions, to produce 1-alkylated isoquinoline derivatives in excellent yields with high regioselectivity. The use of commercially available N-methyl-2-pyrrolidinone makes this process quite simple, more convenient and practical.
Addition of boron enolates to isoquinolinium salts: A facile synthesis of 1-β-keto substituted 2-ethoxycarbonyl-1,2-dihydroisoquinolines and their cyclization
An efficientmethod to synthesize 1-β-keto substituted 2-ethoxycarbonyl (or 2-acetyl)-1,2-dihydroisoquinolines (3) is described, utilizing boron enolates and isoquinolinium salts. The products were treated with sodium ethoxide to afford the corresponding cyclic compounds (6).
Addition of trimethylsilyl enol ethers to isoquinolinium salts: a facile synthesis of 1-(2-oxoalkyl)-2-(ethoxycarbonyl)(or acetyl)-1,2-dihydroisoquinolines and their cyclization for the synthesis of isoquinoline alkaloid skeleton