title: Stereocontrolled synthesis of triazacyclopenta[cd]pentalenes by intramolecular 1,3-dipolar cycloaddition reactions of azomethine imines.
abstract: The construction of triazacyclopenta[cd]pentalene diesters 6 by the reaction of dihydropyrrole alpha-ketoesters 3 with acylated hydrazines was evaluated further as a potential central strategic step in the total syntheses of complex guanidine alkaloids such as palau'amine and styloguanidine. Successful cyclocondensations were realized with acid-stable 2,2,2-trichloroethyl carbazate and thiosemicarbazide, but not tert-butyl carbazate. The substituent on the pyrrolidine nitrogen can be alkoxycarbonyl, sulfonyl, or an N-alkyl-2-acylpyrrole group. Siloxy substitution at C1 of the alpha-ketoester side chain is also tolerated.
authors.affiliation: Department of Chemistry, 516 Rowland Hall, University of California, Irvine, California 92697-2025 leoverma@uci.edu
authors.forename: Guillaume
authors.initials: G
authors.lastname: Bélanger
authors.forename: Fang-Tsao
authors.initials: FT
authors.lastname: Hong
authors.forename: Larry E
authors.initials: LE
authors.lastname: Overman
authors.forename: Bruce N
authors.initials: BN
authors.lastname: Rogers
authors.forename: John E
authors.initials: JE
authors.lastname: Tellew
authors.forename: William C
authors.initials: WC
authors.lastname: Trenkle
mesh_terms: D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
chemical_list: D003517:Cyclopentanes; D007097:Imines; C024646:pentalenene