Synthesis of substituted isoquinolines by electrophilic cyclization of iminoalkynes
Qinhua Huang1, Jack A Hunter, Richard C Larock
1Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Abstract:
The tert-butylimines of o-(1-alkynyl)benzaldehydes and analogous pyridinecarbaldehydes have been cyclized under very mild reaction conditions in the presence of I(2), ICl, PhSeCl, PhSCl, and p-O(2)NC(6)H(4)SCl to give the corresponding halogen-, selenium-, and sulfur-containing disubstituted isoquinolines and naphthyridines, respectively. This methodology accommodates a variety of iminoalkynes and affords the anticipated heterocycles in moderate to excellent yields. Monosubstituted isoquinolines and naphthyridines have been synthesized by the metal-catalyzed ring closure of these same iminoalkynes. The silver-catalyzed ring closure is highly effective in cyclizing aryl-, alkenyl-, and alkyl-substituted iminoalkynes at 50 degrees C.
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