Didactic approach recounting advances and limitations in novel glutathione and cysteine detection (reduced GSH probe) with mixed coumarin, aldehyde, and phenyl-selenium chemistry

We describe the pertinent research steps and analysis, many of which are chemical, to achieve a novel molecular probe for glutathione (GSH) which has been published and patented based on two recent articles: "Exceptional time response, stability and selectivity in doubly-activated phenyl selenium-based glutathione-selective platform" and "Enhanced Doubly Activated Dual Emission Fluorescent Probes for Selective Imaging of Glutathione or Cysteine in Living Systems" (Kim et al., 2015; Mulay et al., 2018). The papers involve coumarin probes. Reaction/detection unfolds with aminothiol attack at an electrophilic ring carbon position. An adjacent -CHO group is heavily involved in resonance aspects of the C-Se position, as well as the binding of the pendant N-group; the coumarin lactone carbonyl also allows for resonance to be achieved (vide infra). The leaving group, -SePh, while precedented in some systems, depends on electronic tuning (Fig. 1). For 1, the response times with GSH was ~100ms; a 100-fold fluorescence increase is observed (Compound 1). The probe also reacts with cysteine (Cys) and homocysteine (Hcy), albeit differently. For glutathione probing, the greater wavelength maxima (1: 550nm, DACP-1: 555nm, DACP-2: 590nm) enabled eventual cell studies (confocal microscopy) and animal studies. The limits of detection (LOD, 1: 270nM DACP-1: 10.1nM DACP-2: 17.0nM), as measured using the 3σ/k method. We provide a didactic presentation from probe conception to probe in vivo testing, etc., with additional considerations presented; a variety of factors/issues (2.1-2.28) help maintain a realistic sequence, a flow from wider to narrower, of the factors that go into developing medical, biological and neurodegenerative disease-related probes, meant to help other researchers follow our intention, gain perspective, and overcome current limitations.

Asymmetric Organocatalyzed Reaction Sequence To Synthesize Chiral Bridged and Spiro-Bridged Benzofused Aminals via Divergent Pathways

A highly efficient asymmetric organocatalysis-triggered reaction sequence is developed. 2-Hydroxy cinnamaldehydes and cyclic N-sulfonyl ketimines were both used as multisite substrates (more than two reactive sites) to access structurally diverse chiral bridged and spiro-bridged benzofused aminal derivatives, where an inseparable equilibrating mixture of isomers can be regioselectively converted into bridged benzofused aminals with different ring connectivities via divergent pathways. Several stereoselective transformations of the resulted bridged aminals are presented.

Synthesis and Chemical Properties of 3-Phosphono-coumarins and 1,2-Benzoxaphosphorins as Precursors for Bioactive Compounds

Coumarins are an important class of natural heterocyclic compounds that have attracted considerable synthetic and pharmacological interest due to their various biological activities. This review emphasizes on the synthetic methods for the preparation of dialkyl 2-oxo-2H-1-benzo- pyran-3-phosphonates and alkyl 1,2-benzoxaphosphorin-3-carboxylates. Their chemical properties as acceptors in conjugate addition reactions, [2+2] and [3+2] cycloaddition reactions are discussed.

Asymmetric organocatalyzed reaction sequence of 2-hydroxy cinnamaldehydes and acyclic N-sulfonyl ketimines to construct diverse chiral bridged polycyclic aminals

2-Hydroxy cinnamaldehydes and acyclic N-sulfonyl ketimines were used as multisite substrates in an iminium catalysis triggered sequential process, leading to diverse chiral bridged polycyclic aminals in a highly regio- and stereoselective manner.

Synthesis and anticancer properties of 3-methylene-4-(2-oxoalkyl)-3,4-dihydrocoumarins

A simple and general strategy for the synthesis of 3-methylene-4-(2-oxoalkyl)-3,4-dihydrocoumarins has been developed.

Catalyst-free one-pot domino reactions for selective synthesis of functionalized 2,8-oxazabicyclo[3.3.1]-nonanes and 5H-indeno[1,2-b]pyridin-5-ones

A simple and efficient method for one-pot selective synthesis of functionalized 2,8-oxazaxabicyclo[3.3.1]nonanes and hydroxy-containing 5H-indeno[1,2-b]pyridin-5-ones under catalyst-free conditions has been developed.