Superacid-Promoted Reactions of N-Acyliminium Ions: An Effective Route to Substituted 3-Oxo-1,2,3,4-tetrahydroisoquinolines and Related Products

Abstract

Intramolecular cyclizations involving N-acyliminium ions are shown to give products in good yields from reactions with CF₃SO₃H (triflic acid). The resulting 3-oxo-1,2,3,4-tetrahydroisoquinolines have been converted in high yields to 1,2-diaryl-1,2,3,4-tetrahydroisoquinolines, which have been recently shown to be selective estrogen receptor modulators. In a reaction using a chiral N-acyliminium ion, cyclization is found to occur in moderately high diastereoselectivity. Several examples of intermolecular triflic acid-promoted reactions are also reported.

Key words

electrophilic aromatic substitutions - N-acyliminium ions - tetrahydroisoquinolines - superacid - superelectrophile

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