2016-01-5Relevant academic research and scientific papers
Porphyrins as Photoredox Catalysts: Experimental and Theoretical Studies
Rybicka-Jasińska, Katarzyna,Shan, Wenqian,Zawada, Katarzyna,Kadish, Karl M.,Gryko, Dorota
, p. 15451 - 15458 (2016)
Metalloporphyrins not only are vital in biological systems but also are valuable catalysts in organic synthesis. On the other hand, catalytic properties of free base porphyrins have been less explored. They are mostly known as efficient photosensitizers for the generation of singlet oxygen via photoinduced energy transfer processes, but under light irradiation, they can also participate in electron transfer processes. Indeed, we have found that free base tetraphenylporphyrin (H2TPP) is an efficient photoredox catalyst for the reaction of aldehydes with diazo compounds leading to α-alkylated derivatives. The performance of a porphyrin catalyst can be optimized by tailoring various substituents at the periphery of the macrocycle at both the β and meso positions. This allows for the fine tuning of their optical and electrochemical properties and hence their catalytic activity.
Palladium-catalyzed epimerization of γ-alkenyl-γ-butyrolactone derivatives
Hon, Yung-Son,Chen, Hsien-Fan,Kao, Chen-Yi,Luo, Ching-Zong
, p. 8468 - 8475 (2010)
γ-Alkenyl-α,β,γ-trisubstituted-γ- butyrolactones (12-16) and γ-alkenyl-furofurandione derivatives (21-Z-24-Z; 21-E-24-E; 25-Z-28-Z; and 25-E-28-E) were successfully epimerized in high yield by a palladium catalyst.
Photocatalytic Reaction of Diazo Compounds with Aldehydes
Rybicka-Jasińska,Ciszewski,Gryko
supporting information, p. 1671 - 1678 (2016/10/13)
Photocatalytic reactions of diazoacetates with aldehydes led to α-alkylated carbonyl compounds instead of the expected cyclopropane derivatives. The reaction requires a dual catalytic system – photocatalysis merged with enamine-iminium catalysis. NMR, EPR, UV/Vis, and ESI-MS analyses provided sufficient data to corroborate the proposed radical mechanism – enamine catalysis merged with photocatalysis. (Figure presented.).
CLAISEN/OZONOLYSIS ALTERNATIVE TO ALKYLATION OF ENOLATE ANIONS. SYNTHESIS OF 1,4-DICARBONYL COMPOUNDS.
Carman, Lenore,Kwart, Lawrence D.,Hudlicky, Tomas
, p. 169 - 182 (2007/10/02)
Several allylic alcohols were subjected to the orthoester Claisen rearrangement to provide the corresponding γ,δ-unsaturated esters in high yields.Ozonolysis of olefinic esters gave excellent yields of the appropriate 1,4-dicarbonyl compounds.
Addition of (Methylthio)methyl p-Tolyl Sulfone to α,β-Unsaturated Carbonyl Compounds
Ogura, Katsuyuki,Yahata, Nobuhiro,Minoguchi, Masanori,Ohtsuki, Kazuo,Takahashi, Kazumasa,Iida, Hirotada
, p. 508 - 512 (2007/10/02)
The lithio derivative of (methylthio)methyl p-tolyl sulfone (1) reacted with various α,β-unsaturated carbonyl compounds to afford adducts in good to high yields.The introduced (methylthio)(p-tolylsulfonyl)methyl group was easily converted to a (methylthio)carbonyl group or a formyl group.When the reaction of 1 with methyl acrylate using sodium hydride as a base was performed in DMF at an ambient temperature,2-(methoxycarbonyl)-4-(methylthio)-4-(p-tolylsulfonyl)cyclohexanone (8) was obtained in 81 percent yield.Furthermore, 8 was shown to be an important intermediate for preparing 2-substituted 2-(methoxycarbonyl)-1,4-cyclohexanediones.
