Sindhu,Mathai; Vijay Nair,G(Regional Research Laboratory(CSIR), 2004)
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Abstract:
The thesis entitled novel 1,3-dipolar cycloaddition reactions of acyclic carbonyl ylides and related chemistry embodies the results of the investigations carried out to explore the reactivity of acyclic carbonyl ylides,generated by the reaction of dicarbomethoxy carbine and aldehydes towards dipolarophiles such as activated styrenes,1,2-and 1,4-quinones. In conclusion ,we have explored the reactivity pattern of acyclic carbonyl ylides derived from dicarbomethoxycarbene and aldehyde towards activated styrenes with a view to develop a stereoselective synthesis of highly substituted tetrahydrofuran derivatives. It was also found that the ylide could be trapped by various 1,2-and 1,4-diones to form dioxolane derivatives. It is noteworthy that the cycloaddition is highly region- and stereoselective. With isatins the ylide preferentially adds to the more electrone deficient carbonyl group making it regiospecific. Hetrocyclic compounds are of pivotal importance in organic chemistry, and enormous efforts have been devoted to develop new methodologies for their synthesis. It is noteworthy in this context that, 1,3-dipolar cycloaddition reaction,otherwise called Huisgen reaction, constitutes one of the most efficient methods for the synthesis of five membered heterocycles. Among the various dipoles, carbonyl ylides have received substiancial attention in recent years largely due to their utility in the synthesis of a wide range of oxygen hetrocycles, which are often found as structural subunits of many bioactive natural products.
Kala, K; Dr. N. Manoj(Cochin University of Science and Technology, July 3, 2016)
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Abstract:
Organic molecules with π-conjugated scaffolds end-capped with electron donor and acceptor groups are widely investigated due to their immense application potentials and hence belong to a promising area of organic chemistry. Donor-acceptor materials have found wide variety of applications such as dyes in dye-sensitised solar cells (DSSCs), organic photovoltaics, organic light emitting diodes, nonlinear optical devices, chemosensors, diagnostic probes and as therapeutic agents. Despite their use in such a wide range of applications, many fundamental properties of donor acceptor materials are still poorly understood. Even simple structural modifications can bring unexpected electronic and photophysical properties and wider understanding of the interaction between donor and acceptor is thus required. Furthermore, many such systems show diversity in properties in solution state or in their condensed state such as crystalline or amorphous forms. For example, some of these molecules show aggregation induced quenching or enhancement in emission in the solid state. Thus, structural motifs that facilitate intermolecular interaction via hydrophobic association, hydrogen bonding or electrostatic effects can lead to excellent control over their supramolecular functions. Some of the important structural types which used as donors are triarylamines, carbazoles, phenothiazine, fluorenes, thiophenes, and oligothiophenes. Strongly electron withdrawing groups or electron deficient heterocyclic systems such as oxadiazoles, diarylborons, quinolines, quinoxalines, thienopyrazines, and benzothiadiazoles, cyanoacetic acid, rhodanine-3-acetic acid, barbituric acid, and thiobarbituric acid etc., have been used as the acceptors in the
design of donor-acceptor systems.