A Very Mild Access to 3,4-Dihydroisoquinolines Using Triphenyl Phosphite-Bromine-Mediated Bischler-Napieralski-Type Cyclization

Daniele Vaccari, Paolo Davoli, Claudia Ori, Alberto Spaggiari, Fabio Prati*

*Università di Modena e Reggio Emilia, Via Campi 183, 41100 Modena, Italy, Email: fabio.pratiunimore.it

D. Vaccari, P. Davoli, C. Ori, A. Spaggiari, F. Prati, Synlett, 2008, 2803-2806.

DOI: 10.1055/s-0028-1083544

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Abstract

Substituted β-phenylethylamides undergo a smooth intramolecular Bischler-Napieralski cyclization to 3,4-dihydroisoquinolines in good to excellent yields when treated with bromotriphenoxyphosphonium bromide at -60˚C in dichloromethane in the presence of triethylamine. The reaction proceeds under very mild conditions via the corresponding iminoyl bromides.

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Key Words

Bischler-Napieralski reaction, phosphonium halides, iminoyl halides, isoquinoline alkaloids, necatorone, triphenyl phosphite

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ID: J60-Y2008-3350