An investigation into the electrophilic cyclisation of N-acyl-pyrrolidinium ions: a facile synthesis of pyrrolo-tetrahydroisoquinolones and pyrrolo-benzazepinones.
The triflic acid-mediated cyclisation of N-arylmethyl- and N-arylethyl-acylpyrrolidinium ions gave moderate to good yields of pyrrolo-tetrahydroisoquinolones and pyrrolo-benzazepinones respectively. Electron-donating R substituents enhanced the rate of reaction and gave higher yields than electron-withdrawing substituents. Substituents on the methyl or ethyl chain in general enhanced the reaction, unless sterically encumbered. The equivalent acylpiperidinium ions cyclised much slower and in lower yield.
King
Frank D
FD
Department of Chemistry, University College London, 20 Gordon Street, London, WC1H 0AJ, UK. f.d.king@ucl.ac.uk
Aliev
Abil E
AE
Caddick
Stephen
S
Copley
Royston C B
RC
D001552:Benzazepines / Q000138:chemical synthesis*; D003500:Cyclization; D007546:Isoquinolines / Q000138:chemical synthesis*; D007700:Kinetics; D011759:Pyrrolidines / Q000737:chemistry*
D001552:Benzazepines; D007546:Isoquinolines; D011759:Pyrrolidines; C032519:pyrrolidine