Diels-Alder reactions: The effects of catalyst on the addition reaction

WOS: 000360870100010The reaction between 2,3-dimethyl-1,3-butadiene and dimethyl 7-oxabicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate is efficiently achieved with small amounts of catalyst, i.e. phenol, AcOH, nafion, and beta-cyclodextrin. Exo-diastereoselective cycloaddition reactions were observed both without catalyst and different catalysts for 48 days. As a result, different products (tricyclicmolecule 5, retro-Diels-Alder product 6, and oxidation product 7) were obtained with different catalysts. In addition, we synthesized Diels-Alders product 8 and tricyclocyclitol 10 via Diels-Alder reaction. The structures of these products were characterized by H-1 NMR, C-13 NMR, MS and IR spectroscopy. (C) 2015 Elsevier B.V. All rights reserved.Mersin University (BAP-FBE KA) [2010-5 YL]; Aksaray University, Science and Technology Application and Research Center, Aksaray, Turkey (State of Planning Organization) [2010K120480]The authors are indebted to Mersin University (BAP-FBE KA (OY) 2010-5 YL) for its financial support of this work and Prof. Dr. Hasan Secen, Prof Dr. Arif Dastan for their help during this work. The authors acknowledge Aksaray University, Science and Technology Application and Research Center, Aksaray, Turkey, for the use of the Bruker SMART BREEZE CCD diffractometer (purchased under grant No. 2010K120480 of the State of Planning Organization)

Synthesis of tricyclic ring systems: [2+2] ketene addition reaction for preparation of tricyclic ketone, alcohol, and lactone derivatives

WOS: 000400020200007The addition of dichloroketene to 1,4-cyclohexadiene was examined. Dichloroketene, which was easily prepared from trichloroacetyl chloride and Zn-Cu, reacted with 1,4-cyclohexadiene in the presence of POCl3 to afford novel racemic products of single addition (5) and double addition (6). The adducts 6 and 7 were reacted separately with MCPBA (meta-chloroperbenzoic acid), H2O2, LiAlH4, and cis-diol 10 was reacted with PCC (pyridinium chlorochromate) to afford lactone, alcohol, and ketone derivatives likely to exhibit biological activity. The structures of all the racemic molecules mentioned in the article were determined from H-1 NMR, C-13 NMR, MS, and IR data.Mersin University [BAP-FBE KA (OY) 2014-1DR, 2015-AP4-1235, BAP-FBE K (EYB) 2011-7 YL]; Aksaray University, Science and Technology Application and Research Center, Aksaray, Turkey [2010K120480]The authors are indebted to Mersin University (BAP-FBE KA (OY) 2014-1DR, 2015-AP4-1235 and BAP-FBE K (EYB) 2011-7 YL) for its financial support of this work. The authors acknowledge Aksaray University, Science and Technology Application and Research Center, Aksaray, Turkey, for the use of the Bruker SMART BREEZE CCD diffractometer (purchased under grant No. 2010K120480 from the State Planning Organization)

Osmoprotectant and antioxidant effects of new synthesized 6-(2-hydroxyethyl)cyclohex-3-enol on barley under drought stress

The aim of present study was synthesize 6-(2-hydroxyethyl)cyclohex-3-enol (11) and investigate its antioxidant properties in barley plants under drought stress. For this aim, 1,4-cyclohexadiene (7) was subjected to [2 + 2] ketene addition reaction with dichloro ketene and the chlorine atoms were reduced. After that, the cyclobutanone ring was converted to a lactone ring and the lactone ring was reduced with LiAlH4. Subsequently, 6-(2-hydroxyethyl)cyclohex-3-enol (13) was obtained with high yield. The structures of the synthesized molecules were clarified by NMR, FTIR, GCMS spectroscopic methods. Two different methods were used to evaluate antioxidant activity of cyclohexenediol 11. One of them was DPPH radical scavenging activity which was used extensively. Also, osmoprotectant and antioxidant effects of 6-(2-hydroxyethyl)cyclohex-3-enol (13) were investigated in barley under drought stress. Drought decreased the relative water content (RWC) and water potential (WP) in barley leaves. Cyclohexenediol 11 treatment remarkably increased RWC and WP in leaves under drought conditions. Superoxide (O−2) and nitric oxide (NO) accumulated under drought. In cyclohexenediol 11 treated-plants, the accumulation O−2 and NO were strongly reduced under drought conditions. Our results showed that cyclohexenediol 11 helped barley plants for maintaining water under drought stress; this makes synthetic cyclitol cyclohexenediol 11 as a good osmoprotectant candidate. Another important result in this study was the strong radical scavenging potential of cyclohexenediol 11. We think that much more comprehensive biochemical studies should be conducted to determine how cyclohexenediol 11 performs the radical scavenge role