Acylisoquinoline derivatives

Isoquinoline Reissert compounds of type 12 could be easily converted to the corresponding 1-cyanoisoquinolines (13) by simple base treatment (4,5) (Scheme 3). This transformation also takes place with high yields when type 12 compounds are oxidized with molecular oxygen in a two-phase system in the presence of phase-transfer catalysts (12-14). It should be mentioned that similar oxidation of dihydro Reissert compounds of type 14 afforded the corresponding dihydroisocarbostyril derivatives (15) (12-14). Base treatment of isoquinoline Reissert eompounds followed by intramolecular rearrangement, due to the absence of a proper intermolecular reaction partner, results in 1-acylisoquinoline derivatives (18) (3). 

The synthetic potential of 4-acylisoquinoline derivatives is illustrated by the conversion of 70 into 7166 and of 72 into 73.87... 

The formation of substituted isoquinolines was achieved by E. Awuah and A. Capretta. In the first step an amine reacted with an aryl acetic acid in POCI3 and toluene under microwave (MW) irradiation at 140°C for 30 min to afford 2-(3,4-dimethoxyphenyl)ethylamine (92). Subsequent oxidation of tetrahydroisoquinolines 92 with air using Pd/C in toluene led to the final products, acylisoquinoline derivatives 93 (Scheme 34) (10JOC5627). 

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