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pyridinium-salt
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Tandem dinucleophilic cyclization of cyclohexane-1,3-diones with pyridinium salts
, Article Beilstein Journal of Organic Chemistry ; Volume 9 , 2013 , Pages 1119-1126 ; 18605397 (ISSN) ; Moghaddam, F. M ; Mkrtchyan, S ; Semeniuchenko, V ; Supe, L ; Villinger, A ; Langer, P ; Laroshenko, V. O ; Sharif University of Technology
2013
Abstract
The cyclization of cyclohexane-1,3-diones with various substituted pyridinium salts afforded functionalized 8-oxa-10-aza-tricyclo[7.3.1.0 2,7]trideca-2(7),11-dienes. The reaction proceeds by regioselective attack of the central carbon atom of the 1,3-dicar-bonyl unit to 4-position of the pyridinium salt and subsequent cyclization by base-assisted proton migration and nucleophilic addition of the oxygen atom to the 2-position, as was elucidated by DFT computations. Fairly extensive screening of bases and additives revealed that the presence of potassium cations is essential for formation of the product
Synthesis of Heterocyclic Compounds via Domino Knoevenagel Hetero Diels–Alder Reaction on Thiocarbonyls and Investigation of Tandem Dinucleophilic Addition on Pyridinium Salts
, Ph.D. Dissertation Sharif University of Technology ; Matloubi Moghaddam, Firouz (Supervisor)
Abstract
In the first chapter, three efficient synthesis of novel polyheterocyclic indole and thiochromone-annulated thiopyranocoumarin derivatives are achieved via domino Knoevenagel hetero Diels–Alder reaction of O-acrylated and O-propargylated salicylaldehyde derivatives with indolin-2-thiones and 4-hydroxy dithiocoumarin. The domino Knoevenagel-hetero-Diels–Alder reactions are very efficient process that allows the formation of two or more rings at once, avoiding sequential chemical transformations. The products are formed in good-to-excellent yields with high regio- and stereoselectivity. The major advantage of this reaction is the ease of the work-up during which the products can be isolated...