A novel application of the oxidizing properties of urea nitrate and peroxydisulfate-cobalt(II): aromatization of NAD(P)H model Hantzsch 1,4-dihydropyridines

An Expeditious Oxidative Aromatization of Hantzsch 1,4-Dihydropyridines to Pyridines Using Cetyltrimethylammonium Peroxodisulfate: A Phase Transferring Oxidant

“…13,38 To the best of our knowledge, cetyltrimethylammonium peroxodisulphate (CATPDS) is not used in oxidation of 1,4-DHP. Thus, we hoped that the CATPDS would be superior to the previously reported other peroxodisulphate oxidants because of i) less reaction time (ii) high yield (iii) no dealkylation of 4-n-alkyl/alkenyl substituents of 1,4-DHP i.e., selective oxidation (iv) avoidance of toxicity of many transition metal involved in such process (v) solubility in most organic solvent (vi) commercial availability.…”

“…4 These ubiquitous features always encourage synthetic chemist to explore improved protocols for the synthesis as well as the oxidation of 1,4-DHPs. A variety of reagents has been utilized for this oxidative conversion: S-nitrosoglutathion, 5 N2O4 complex of 18-crown-6, 6 photochemical oxidation, 7 Zr(NO3)4, 8 tetrakis-(pyridine)cobalt(II) dichromate, 9 nicotinum dichromate, 10 cytochrome P-450, 11 electrochemical catalysis, 12 urea nitrate, 13 peroxydisulfateCo(II), 13 Mn(OAc) 3 , 14 Vanadium salts, 15 tetra-n-butylammonium periodate, 16 AlCl3, 17 benzyltriphenylphosphonium peroxymonosulfate, 18 Mn(TPP)Cl-PSI/NaIO4, 19 [30][31][32][33][34][35] In spite of an overabundance of methods for this conversion, limitations like extended reaction times, poor yields and use of strong or toxic oxidant has led to the investigation of many alternative procedures.…”

Silver(I) Catalyzed Photochemical Oxidation of Methylene Blue and Safranine-O by Peroxydisulphate: A Green Chemical Approach

“…4-alkyl or aryl substituted derivatives of 1,4-dihydropyridine were readily oxidized by urea nitrate. This oxidation reaction was also affected by peroxydisulphate in presence of cobalt(II) [19]. Photocatalytic reaction by Fe(III)-citrate complex and its effect on the photodegradation of atrazine in aqueous solution was observed by Ou et al [20].…”

Sulfur and Phosphorus Peroxides

“…Behrman has studied the ortho -para ratio in this reaction and found that the ortho product predominates over the para product (in contrast with the Elbs reaction) (equation 15 Recently, Perumal and coworkers reported aromatization of NAD(P)H model Hantzch 1,4-dihydropyridnes using potassium peroxydisulfate/Co(II) 65 .…”