Stereocontrolled synthesis of triazacyclopenta[cd]pentalenes by intramolecular 1,3-dipolar cycloaddition reactions of azomethine imines.
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.
Bélanger
Guillaume
G
Department of Chemistry, 516 Rowland Hall, University of California, Irvine, California 92697-2025 leoverma@uci.edu
Hong
Fang-Tsao
FT
Overman
Larry E
LE
Rogers
Bruce N
BN
Tellew
John E
JE
Trenkle
William C
WC
D003517:Cyclopentanes / Q000138:chemical synthesis* / Q000737:chemistry*; D007097:Imines / Q000737:chemistry*; D015394:Molecular Structure; D013237:Stereoisomerism
D003517:Cyclopentanes; D007097:Imines; C024646:pentalenene