Synthesis of tetrahydroisoquinolines via intramolecular electrophilic aromatic substitution reactions of Pummerer-derived substituted N-benzyl-N-tosyl-α-aminothionium ions

Abstract Conjugate addition to (phenylsulfinyl)ethene 1 of substituted benzylic amines 2 followed by N -tosylation gives substituted N -benzyl- N -tosyl-2-amino-1-(phenylsulfinyl)ethanes 3 . Treatment of 3 with trimethylsilyl trifluoromethanesulfonate-Hunig's base gives 4-(phenylsulfenyl)- N -tosyl-1,2,3,4-tetrahydroisoquinolines 4 via presumed intramolecular trapping of Pummerer-derived substituted N -benzyl- N -tosyl-α-aminothionium ions 5 .