Synthesis, Characterization, and Crystal Structure of Some New Tetrahydroisoquinolines and Related Tetrahydrothieno[2,3‑c]isoquinolines

The starting compounds 7-acetyl-8-aryl-4-cyano-1,6-dimethyl-6-hydroxy-5,6,7,8-tetrahydroisoquinoline­(2H)-3-thiones 3a,b were synthesized and reacted with some N-aryl-2-chloroacetamides 4a–e in the presence of sodium acetate to produce 7-acetyl-8-aryl-3-(N-arylcarbamoylmethylsulfanyl)-4-cyano-1,6-dimethyl-6-hydroxy-5,6,7,8-tetrahydroisoquinolines 5a–g. Upon heating in ethanol containing sodium ethoxide, they underwent intramolecular Thorpe–Zeigler cyclization, affording the corresponding 7-acetyl-1-amino-6-aryl-2-(N-arylcarbamoyl)-5,8-dimethyl-8-hydroxy-6,7,8,9-tetrahydrothieno­[2,3-c]­isoquinolines 6a–g. Compounds 6c,g,f were converted into the corresponding 1–(1-pyrrolyl) derivatives 7a–c by heating with 2,5-dimethoxytetrahydrofuran in glacial acetic acid. Structures of all synthesized compounds were characterized by elemental and spectral analyses. Also, the crystal structure of compounds 5a was determined by X-ray diffraction analysis.