Synthesis 2006(11): 1775-1780  
DOI: 10.1055/s-2006-942387
PAPER
© Georg Thieme Verlag Stuttgart · New York

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

Yiliang Zhang, Patrick J. Kindelin, Daniel J. DeSchepper, Chong Zheng, Douglas A. Klumpp*
Department of Chemistry and Biochemistry, Northern Illinois University, DeKalb, IL 60115, USA
Fax: +1(815)7534802; e-Mail: dklumpp@niu.edu;
Further Information

Publication History

Received 3 January 2006
Publication Date:
08 May 2006 (online)

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.