title: Regioselective Iron-Catalyzed [2 + 2 + 2] Cycloaddition Reaction Forming 4,6-Disubstituted 2-Aminopyridines from Terminal Alkynes and Cyanamides.
abstract: Iron complexes bound by redox-active pyridine dialdimine (PDAI) ligands catalyze the cycloaddition of two terminal alkynes and one cyanamide. The reaction is both chemo- and regioselective, as only 4,6-disubstituted 2-aminopyridine products are formed in moderate to high yields. Isolation of an iron azametallacycle (4) suggests that catalyst deactivation occurs with a large excess of cyanamide over longer reaction times. Fe-catalyzed cycloaddition allowed for a straightforward synthesis of a variety of aminopyridines, including known estrogen receptor ligands.
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
authors.forename: Nathan A
authors.initials: NA
authors.lastname: Spahn
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
authors.forename: Minh H
authors.initials: MH
authors.lastname: Nguyen
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
authors.forename: Jonas
authors.initials: J
authors.lastname: Renner
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
authors.forename: Timothy K
authors.initials: TK
authors.lastname: Lane
authors.affiliation: Department of Chemistry, University of Utah , 315 South 1400 East, Salt Lake City, Utah 84112, United States.
authors.forename: Janis
authors.identifier: 0000-0003-3569-1967
authors.initials: J
authors.lastname: Louie
mesh_terms: D000480:Alkynes / Q000737:chemistry*; D000631:Aminopyridines / Q000138:chemical synthesis* / Q000737:chemistry; D002384:Catalysis; D003484:Cyanamide / Q000737:chemistry*; D061565:Cycloaddition Reaction; D058085:Iron Compounds / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D000480:Alkynes; D000631:Aminopyridines; D058085:Iron Compounds; D003484:Cyanamide; C032439:alpha-aminopyridine