6. Rehybridization of the Acceptor (RICT) 3908 7. Planarization of the Molecule (PICT) 3909 III. Fluorescence Spectroscopy 3909 A. Solvent Effects and the Model Compounds 3909 1. Solvent Effects on the Spectra 3909 2. Steric Effects and Model Compounds 3911 3. Bandwidths 3913 4. Isoemissive Points 3914 B. Dipole Moments 3915 C. Radiative Rates and Transition Moments 3916 1. Quantum Yields and Radiationless Deactivation Processes 3916

Structural Changes Accompanying Intramolecular Electron Transfer: Focus on Twisted Intramolecular Charge-Transfer States and Structures

Fluorescent labeling of biomolecules with organic probes.

Stereochemical Control in Organic-Synthesis Using Silicon-Containing Compounds

Photolabile protecting groups enable biochemists to control the release of bioactive compounds in living tissue. ‘Caged compounds’
(photoactivatable bioagents) have become an important tool to study the events that follow chemical signalling in, e.g., cell biology and the neurosciences. The possibilities are by no means exhausted. Progress will depend on the development of photoremovable protecting groups that satisfy the diverse requirements of new applications—a challenging task for photochemists.

https://link.springer.com/content/pdf/10.1039/b200777k.pdf

Photoremovable protecting groups: reaction mechanisms and applications

2.1. Oxygen Nucleophiles 3174 2.2. Nitrogen Nucleophiles 3177 3. Ag(I)-Mediated Addition of Nucleophiles to Allenes 3178 3.1. Oxygen Nucleophiles 3178 3.1.1. Allenic Alcohols 3178 3.1.2. Allenic Aldehydes and Ketones 3179 3.1.3. Allenic Acids 3180 3.2. Nitrogen Nucleophiles 3180 3.2.1. Allenic Amines 3180 3.2.2. Allenic Sulfonamides 3182 3.2.3. Allenic Carbamates 3182 3.2.4. Allenic Amides 3182 3.2.5. Allenic Oximes 3183 4. Ag(I)-Mediated Additions to Alkenes 3183 5. Ag(I)-Mediated Cycloaddition Reactions 3185 5.1. 1,3-Dipolar Cycloaddition Reactions of Azomethine Ylides 3185

Silver-mediated synthesis of heterocycles.

Synthesis and fluorescence properties of substituted 7-aminocoumarin-3-carboxylate derivatives

Template-directed intramolecular c-glycosidation. cation-mediated synthesis of ketooxetanes from thioglycosides

Practical improvements have been made to previous work on the synthesis of the title compound, particularly in the final step of converting its precursor chloroacetamide to the required iodoacetamide. Improvements include removal of contaminant(s) that inhibit the chloride to iodide exchange and better extraction procedures to minimise losses in work-up. The modified conditions for this step may be useful for synthesis of other thiol-reactive dyes where solubility of the dye is problematic.

Optimised synthesis of 6-iodoacetamidotetramethylrhodamine

Bicyclic ketooxetanes 5a, 5b and 8 are formed with excellent stereoselectivity on treatment of (2-pyridylthio)glycosidic silyl enol ethers 1a, 1b and 2 with silver(I) trifluoromethanesulfonate.

Stereoselective template-directed C-glycosidation. Synthesis of bicyclic ketooxetanes via intramolecular cyclization reactions of (2-pyridylthio)glycosidic silyl enol ethers

4-Trifluoromethyl- or 6-bromo-substituted 7-diethylaminocoumarin-3-carboxamide derivatives 2 and 3, each containing a maleimide have been synthesized as potential fluorescent labeling reagents for thiol groups in proteins and their fluorescence properties have been determined. The 4-trifluoromethyl substituted compound 2 has a significantly greater Stokes shift than the comparable compound lacking this group, but both the new coumarins have low fluorescence quantum yields (ϕf). When a 4-trifluoromethyl substituent is present, the 3-carboxamide is unusually labile to hydrolysis. Bromination of ethyl 7-diethylaminocoumarin-3-carboxylate 17 gave the 6- and 8-bromo derivatives 18 and 19 respectively, and also the 8-bromo-7-monoethylamino compound 20. ϕf for the latter compound is 100-fold greater than for its diethylamino analogue 19. Fluorescence lifetime measurements support an interpretation based on the twisted intramolecular charge transfer (TICT) model to explain these large differences in ϕf.

V. Ranjit N. Munasinghe

Papers

Synthesis and fluorescence properties of substituted 7-aminocoumarin-3-carboxylate derivatives

Template-directed intramolecular c-glycosidation. cation-mediated synthesis of ketooxetanes from thioglycosides

Optimised synthesis of 6-iodoacetamidotetramethylrhodamine

Stereoselective template-directed C-glycosidation. Synthesis of bicyclic ketooxetanes via intramolecular cyclization reactions of (2-pyridylthio)glycosidic silyl enol ethers

Synthesis and Fluorescence Properties of Substituted 7‐Aminocoumarin‐3‐carboxylate Derivatives.