The use of an electrophile carrier to determine the number of intermediates in the chlorination of 1-methylpyrrole

Michael De Rosa, Manuel Marquez

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Abstract

A kinetic and product study of the dichloroacetic acid catalyzed chlorination of 1-methylpyrrole with 3- and 4-substituted N-chlorobenzamides was carried out. Protonated N-chlorobenzamides served as carriers of CI+. A Hammett correlation was obtained with ρ=-0.68 (r=0.98, n=8). General acid catalysis was observed with α=0.48 (r=0.99 and n=7). The yields of 2-chlorination (84±0.7%) and 3-chlorination (2.6±0.4%) were essentially constant (constant intramolecular selectivity) as the substituent on the N-chlorobenzamide was varied. Observation of constant intramolecular selectivity indicated that two intermediates were formed during the acid catalyzed chlorination of 1-methylpyrrole with N-chlorobenzamides. The carrier method is applicable to all types of aromatic systems and limited only by the availability of suitable carrier molecules.

Original languageEnglish (US)
Pages (from-to)2125-2129
Number of pages5
JournalTetrahedron
Volume59
Issue number12
DOIs
Publication statusPublished - Mar 17 2003

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All Science Journal Classification (ASJC) codes

  • Biochemistry
  • Drug Discovery
  • Organic Chemistry

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