N,N'-Ethylene-bis(benzoylacetoniminato) Copper (II), Cu(C22H22N2O2), a New Reagent for Aromatization of Hantzsch 1,4-Dihydropyridines

Abstract

A variety of Hantzsch 1,4-dihydropyridines were oxidized to their corresponding pyridines in high yields in the presence of Cu(C 22 H 22 N 2 O 2 ) in refluxing acetic acid.

Cu-Catalyzed Pyridine Synthesis via Oxidative Annulation of Cyclic Ketones with Propargylamine

“…It proceeds via Cu­(II) reduction and oxidation of alcohols, used as solvents, or as a result of a Glaser reaction of terminal alkynes employed as substrates . Therefore, it would be logical to propose that Cu­(II) compounds play an important role in the catalytic cycle, as they are known catalysts for imine formation, as well as for dihydropyridine oxidative aromatization. , The modified plausible mechanism proposed by us is represented in Scheme . In the first step, imine 29 is formed from the corresponding ketone 22 and propargylamine 18 .…”

Mild oxidative aromatization of 1,4-dihydropyridines with trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxalane promoted by ammonium bromide/HOAc in water/MeCN

“…As regards the importance of gem-dihydroperoxides, trans-3,5-dihydroperoxy-3,5-dimethyl-1,2-dioxalane (DHPDMO) has been synthesized and used as a new, solid, and powerful oxidant in organic synthesis by our research group (Anniyappan et al, 2002;Dehghanpour, Heravi, & Derikvand, 2007;Fang, Liu, & Li, 2007;Filipan-Litvić, Litvić, & Vinkinić, 2008a;Filipan-Litvić, Litvić, & Vinkinić, 2008b;Gorjizadeh & AbdollahiAlibeik, 2011;Heravi, Behbahani, Oskooie, & Shoar, 2005;Heravi et al, 2009;Karade, Gampawar, Kondre, & Shinde, 2008;Ko & Kim, 1999;Mao, Jin, Liu, & Wu, 2000;Mashraqui & Karnik, 1998;Zolfigol et al, 2005;Zeynizadeh, Dilmaghani, & Mirzaei, 2007). DHPDMO is prepared easily from acetyl acetone and aqueous hydrogen peroxide in the presence of silica sulfuric acid (SSA) (Anniyappan et al, 2002) (Scheme 1).…”