Synthesis of tetrahydroisoquinolines via intramolecular electrophilic aromatic substitution reactions of Pummerer-derived substituted N-benzyl-N-tosyl-α-aminothionium ions
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-Hünig's base gives 4-(phenylsulfenyl)-N-tosyl-1,2,3,4-tetrahydroisoquinolines 4via presumed intramolecular trapping of Pummerer-derived substituted N-benzyl-N-tosyl-α-aminothionium