Indolizines. I. A direct synthesis of acylindolizines from substituted pyridinium salts

1972 ◽  
Vol 25 (5) ◽  
pp. 1003 ◽  
Author(s):  
I Dainis
Keyword(s):  
Aldol Condensation ◽  
Direct Synthesis ◽  
Reaction System ◽  
Reaction Scheme ◽  
Aliphatic Acid ◽  
Pyridinium Salts ◽  
Thermal Cyclization ◽  
One Step ◽  
Competing Pathways

Several routes to 1-formylmethyl-2-methylpyridinium bromide have been investigated. Chichibabin cyclization of this salt to indolizine fails because the reaction system favours an intermolecular aldol condensation. A general one-step synthesis of acyl-and diacyl-indolizines from 1-(β-oxo)-alkyl-2-alkyl- and 1-(β-oxo)alkyl-2-benzyl-pyridinium salts is described. This synthesis, as effected by the anhydride of a weak aliphatic acid and its sodium salt, also gives isomeric products and these have provided a mechanistic reaction scheme of three competing pathways. 1-Acyl-2,3-disubstituted and 3-acyl-1,2-disubstituted indolizines are formed from the relevant salts by Chichibabin cyclization and subsequent in situ acylation. 1-Acetonyl-2-methylpyridinium bromide gives useful yields of 3-acyl-and 1,3-di-acyl-indolizines by this pathway and also via 1-acetonyl-2-acetylmethylene-l,2-dihydropyridine. The reaction of the corresponding 1-phenacyl salt involves acylated intermediates of type (14) and (15), and has provided evidence for the rearrangement of the diacylmethylides (15) to acylmethines (14). A facile thermal cyclization of 2-phenylpyridinium diphenacylmethylide to 3-benzoyl-1,2-diphenylindolizine is reported.

Direct Synthesis of Enones by Visible-Light-Promoted Oxygenation of Trisubstituted Olefins Using Molecular Oxygen

Synlett ◽  
2020 ◽  
Vol 31 (14) ◽  
pp. 1372-1377
Author(s):  
Shinji Harada ◽  
Daiki Matsuda ◽  
Takahiro Morikawa ◽  
Atsushi Nishida
Keyword(s):  
Visible Light ◽  
Molecular Oxygen ◽  
Active Oxygen Species ◽  
Direct Synthesis ◽  
Reaction System ◽  
Active Oxygen ◽  
Oxygen Species ◽  
Mechanistic Studies ◽  
Trisubstituted Olefins ◽  
One Step

A one-step synthesis of enones from olefins is described. The reaction was performed under visible-light irradiation in the presence of molecular oxygen and a photocatalyst. The reaction proceeded with various types of trisubstituted olefins to give enones in good yields with high regioselectivity. In particular, oxygen- and nitrogen-containing functional groups, heteroaromatic rings, and cyclopropanes were tolerated. Mechanistic studies and previous reports indicated that the active oxygen species generated in the reaction system is singlet oxygen.

scholarly journals Effect of In-Situ Dehydration on Activity and Stability of Cu–Ni–K2O/Diatomite as Catalyst for Direct Synthesis of Dimethyl Carbonate

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 343 ◽  
Author(s):  
Dongmei Han ◽  
Yong Chen ◽  
Shuanjin Wang ◽  
Min Xiao ◽  
Yixin Lu ◽  
...  
Keyword(s):  
Dimethyl Carbonate ◽  
Direct Synthesis ◽  
Fixed Bed ◽  
Reaction System ◽  
Space Velocity ◽  
Trapping Efficiency ◽  
Gas Space ◽  
Water Trapping ◽  
Reaction Equilibrium

An in-situ dehydrating system built in a continuous flow fixed-bed bubbling reactor for direct synthesis of dimethyl carbonate (DMC) was designed. 3A molecular sieve (MS) was selected as the ideal dehydrating agent and the water trapping efficiency was studied. The effect of dehydrating agent/catalyst ratio, the dehydrating temperature and pressure, as well as the space velocity on the direct DMC synthesis catalyzed by K2O-promoted Cu–Ni was further investigated. These results demonstrated that 3A MS could effectively dehydrate the reaction system at the optimal conditions of 120 °C and 1.0 MPa with gas space velocity (GHSV) of 600 h−1, thereby greatly shifting the reaction equilibrium toward high DMC yield. Higher DMC yield of 13% was achieved compared with undehydrated reaction. Moreover, the catalyst can be highly stabilized by 3A MS dehydration with stable performs over 22 h.

scholarly journals One-Step Direct Synthesis of SiO2 -TiO2 Composite Nanoparticle Assemblies with Hollow Spherical Morphology

2017 ◽  
Vol 2017 (24) ◽  
pp. 3016-3016
Author(s):  
Hien Thi Thu Nguyen ◽  
Teppei Habu ◽  
Masataka Ohtani ◽  
Kazuya Kobiro
Keyword(s):  
Direct Synthesis ◽  
Spherical Morphology ◽  
Nanoparticle Assemblies ◽  
Composite Nanoparticle ◽  
One Step

In situ formation of highly exposed NiPS3 nanosheets on nickel foam as an efficient 3D electrocatalyst for overall water splitting

2021 ◽  
Author(s):  
Liang Fang ◽  
Yanping Xie ◽  
Peiyin Guo ◽  
Jingpei Zhu ◽  
Shuhui Xiao ◽  
...  
Keyword(s):  
Water Splitting ◽  
Nickel Foam ◽  
Chemical Vapor ◽  
Bifunctional Catalyst ◽  
Vapor Transport ◽  
Chemical Vapor Transport ◽  
Overall Water Splitting ◽  
One Step ◽  
Transport Method

Vertical NiPS3 nanosheets in situ grown on conducting nickel foam were fabricated by a facile one-step chemical vapor transport method and used as an efficient bifunctional catalyst for overall water splitting.

scholarly journals Au Modified F-TiO2 for Efficient Photocatalytic Synthesis of Hydrogen Peroxide

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3844
Author(s):  
Lijuan Li ◽  
Bingdong Li ◽  
Liwei Feng ◽  
Xiaoqiu Zhang ◽  
Yuqian Zhang ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Reaction System ◽  
Reaction Medium ◽  
Pure Tio2 ◽  
H2o2 Production ◽  
Tio2 Photocatalyst ◽  
H2o2 Decomposition ◽  
Spin Resonance ◽  
Photocatalytic Synthesis

In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F− modification inhibits the H2O2 decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F− modification and without F− modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst.

scholarly journals Chlorine-Functional Silsesquioxanes (POSS-Cl) as Effective Flame Retardants and Reinforcing Additives for Rigid Polyurethane Foams

Molecules ◽  
2021 ◽  
Vol 26 (13) ◽  
pp. 3979
Author(s):  
Anna Strąkowska ◽  
Sylwia Członka ◽  
Karolina Miedzińska ◽  
Krzysztof Strzelec
Keyword(s):  
Flame Retardants ◽  
Elevated Temperatures ◽  
Bending Strength ◽  
Reaction System ◽  
Fire Retardant ◽  
Polyurethane Foams ◽  
Polymerization Reaction ◽  
Three Point Bending ◽  
One Step

The subject of the research was the production of silsesquioxane modified rigid polyurethane (PUR) foams (POSS-Cl) with chlorine functional groups (chlorobenzyl, chloropropyl, chlorobenzylethyl) characterized by reduced flammability. The foams were prepared in a one-step additive polymerization reaction of isocyanates with polyols, and the POSS modifier was added to the reaction system in an amount of 2 wt.% polyol. The influence of POSS was analyzed by performing a series of tests, such as determination of the kinetics of foam growth, determination of apparent density, and structure analysis. Compressive strength, three-point bending strength, hardness, and shape stability at reduced and elevated temperatures were tested, and the hydrophobicity of the surface was determined. The most important measurement was the determination of the thermal stability (TGA) and the flammability of the modified systems using a cone calorimeter. The obtained results, after comparing with the results for unmodified foam, showed a large influence of POSS modifiers on the functional properties, especially thermal and fire-retardant, of the obtained PUR-POSS-Cl systems.

ChemInform Abstract: A New and Direct Synthesis of 1-Acylamino-2,6-diaryl Pyridinium Salts.

ChemInform ◽  
2010 ◽  
Vol 29 (39) ◽  
pp. no-no
Author(s):  
F. RIVIERE ◽  
V. ROMANENKO ◽  
M.-R. MAZIERES ◽  
M. SANCHEZ ◽  
J.-G. WOLF
Keyword(s):  
Direct Synthesis ◽  
Pyridinium Salts
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