Substituent effects of the cycloaddition reaction of 7-substituted 5H-benzocycloheptenes with singlet oxygen and the chemistry of the benzocycloheptene endoperoxides

2005 ◽  
Vol 83 (3) ◽  
pp. 227-235 ◽  
Author(s):  
Murat Güney ◽  
Zeynep Çelik Ceylan ◽  
Arif Daştan ◽  
Metin Balci
Keyword(s):  
Reaction Mechanism ◽  
Singlet Oxygen ◽  
Electronic Effect ◽  
Cycloaddition Reaction ◽  
Substituent Effects ◽  
Reaction Conditions ◽  
Effect Of Substituents

The cycloaddition reaction of 7-substituted 5H-benzocycloheptenes with singlet oxygen and the chemistry of the obtained endoperoxides were investigated. Reaction of carboethoxy-substituted endoperoxide with NEt3 gave a mixture of products; hydroxyketone, diketone, and carboethoxy-substituted keto–enol tautomers, whereas the reaction of methyl-substituted endoperoxide only formed a diketone under the same reaction conditions. Thermolysis, thiourea, and CoTPP reactions of the endoperoxides were also studied. The reaction mechanism and electronic effect of substituents were discussed.Key words: benzocycloheptene, photooxygenation, endoperoxides, rearrangement, CoTPP.

The effects controlling the oxygen basicity in alkoxysilanes (RO)nSi(CH3)4-n. The mutual polarizability effect of alkoxy groups attached to silicon

1979 ◽  
Vol 44 (3) ◽  
pp. 750-755 ◽  
Author(s):  
Josef Pola ◽  
Marie Jakoubková ◽  
Václav Chvalovský
Keyword(s):  
Regression Analysis ◽  
Linear Regression ◽  
Electronic Effect ◽  
Linear Regression Analysis ◽  
Effect Of Substituents ◽  
Relative Basicity ◽  
Polarizability Effect ◽  
Alkoxy Groups ◽  
Individual Series

Relative basicity of the oxygen in alkoxysilanes (RO)nSi(CH3)3-n having n = 1-4 and various electrondonating and electronwithdrawing groups R measured as Δν(OH) of phenol due to its interaction with these compounds in CCl4 is shown to be chiefly controlled by the electronic effect of substituents R. Linear regression analysis of the Δν(OH) vs n relatioship for individual series (RO)nSi(CH3)4-n suggests the operation of the polarizability effect of RO groups becoming more important with increasing electronwithdrawing nature of R.

scholarly journals Ring-Opening Copolymerization of Cyclohexene Oxide and Cyclic Anhydrides Catalyzed by Bimetallic Scorpionate Zinc Catalysts

Polymers ◽  
2021 ◽  
Vol 13 (10) ◽  
pp. 1651
Author(s):  
Felipe de la Cruz-Martínez ◽  
Marc Martínez de Sarasa Buchaca ◽  
Almudena del Campo-Balguerías ◽  
Juan Fernández-Baeza ◽  
Luis F. Sánchez-Barba ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Reaction Mechanism ◽  
Catalytic System ◽  
Phthalic Anhydride ◽  
Ring Opening ◽  
High Selectivity ◽  
Zinc Complexes ◽  
Cyclohexene Oxide ◽  
Reaction Conditions ◽  
Cyclic Anhydrides

The catalytic activity and high selectivity reported by bimetallic heteroscorpionate acetate zinc complexes in ring-opening copolymerization (ROCOP) reactions involving CO2 as substrate encouraged us to expand their use as catalysts for ROCOP of cyclohexene oxide (CHO) and cyclic anhydrides. Among the catalysts tested for the ROCOP of CHO and phthalic anhydride at different reaction conditions, the most active catalytic system was the combination of complex 3 with bis(triphenylphosphine)iminium as cocatalyst in toluene at 80 °C. Once the optimal catalytic system was determined, the scope in terms of other cyclic anhydrides was broadened. The catalytic system was capable of copolymerizing selectively and efficiently CHO with phthalic, maleic, succinic and naphthalic anhydrides to afford the corresponding polyester materials. The polyesters obtained were characterized by spectroscopic, spectrometric, and calorimetric techniques. Finally, the reaction mechanism of the catalytic system was proposed based on stoichiometric reactions.

Local structural changes in polyamorphous (Ni,Fe)Ox electrocatalysts suggest a dual-site oxygen evolution reaction mechanism

2021 ◽  
Author(s):  
Martin Schon ◽  
Oliver Calderon ◽  
Nick Randell ◽  
Santiago Jimenez Villegas ◽  
Katelynn M. Daly ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Oxygen Evolution ◽  
Oxygen Evolution Reaction ◽  
Structural Changes ◽  
Mixed Metal Oxides ◽  
Reaction Conditions ◽  
Nickel Iron ◽  
Alkaline Reaction ◽  
Dual Site ◽  
Economical Alternative

Amorphous nickel-iron mixed metal oxides have been shown to be extremely efficient oxygen evolution reaction (OER) electrocatalysts with good stability in alkaline reaction conditions. Thus, they offer an economical alternative...

scholarly journals Visible Light-Enabled Paternò-Büchi Reaction via Triplet Energy Transfer for the Synthesis of Oxetanes

2020 ◽  
Author(s):  
Katie Rykaczewski ◽  
Corinna Schindler
Keyword(s):  
Energy Transfer ◽  
Visible Light ◽  
Uv Light ◽  
Cycloaddition Reaction ◽  
High Energy ◽  
Triplet Energy ◽  
Reaction Conditions ◽  
Triplet Energy Transfer

<div> <p>One of the most efficient ways to synthesize oxetanes is the light-enabled [2+2] cycloaddition reaction of carbonyls and alkenes, referred to as the Paternò-Büchi reaction. The reaction conditions for this transformation typically require the use of high energy UV light to excite the carbonyl, limiting the applications, safety, and scalability. We herein report the development of a visible light-mediated Paternò-Büchi reaction protocol that relies on triplet energy transfer from an iridium-based photocatalyst to the carbonyl substrates. This mode of activation is demonstrated for a variety of aryl glyoxylates and negates the need for both, visible light-absorbing carbonyl starting materials or UV light to enable access to a variety of functionalized oxetanes in up to 99% yield.</p> </div> <br>

A New Simple Procedure for the Synthesis of Heptamethyl Cyclohepta-1,3,5-triene-1,2,3,4,5,6,7-heptacarboxylate

Synlett ◽  
2018 ◽  
Vol 29 (09) ◽  
pp. 1157-1160 ◽  
Author(s):  
Alexander Belyy ◽  
Dmitry Platonov ◽  
Rinat Salikov ◽  
Anastasiya Levina ◽  
Yury Tomilov
Keyword(s):  
Reaction Mechanism ◽  
Nmr Spectroscopy ◽  
Simple Procedure ◽  
Reaction Conditions

A new and simple procedure for the synthesis of heptamethyl cyclohepta-1,3,5-triene-1,2,3,4,5,6,7-heptacarboxylate in a 51% yield is presented. An optimization of the reaction conditions was performed, and a convenient protocol for the isolation of the reaction product was developed. The structure of the key electrophilic intermediate was determined by means of NMR spectroscopy, and a plausible reaction mechanism is proposed.

Synthetic and Mechanistic Studies on 2,3-Dihydrobenzo[b][1,4]-oxaselenines Formation from Selenocyanates

Synthesis ◽  
2020 ◽  
Vol 52 (11) ◽  
pp. 1643-1658
Author(s):  
Sergio H. Szajnman ◽  
Juan B. Rodriguez ◽  
María N. Chao ◽  
Mauricio Cattaneo ◽  
Jonathan Sanchez Gonzalez ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Aromatic Ring ◽  
Relevant Information ◽  
Point Of View ◽  
Cyclization Reaction ◽  
Mechanistic Studies ◽  
Reaction Conditions

An expedient preparation of selenium-containing hetero­cycles via an m-chloroperbenzoic acid-mediated seleno-annulation starting from selenocyanate derivatives is described. In spite of its significance, this cyclization reaction is virtually understudied not only from the point of view of its scope, but also from the mechanistic aspects associated to this remarkable transformation. In this sense, several selenocyanate and thiocyanate derivatives bearing an aromatic ring were evaluated as substrates under different reaction conditions of this interesting cyclization yielding important insights on its scope as well as relevant information on the reaction mechanism.

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