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β-Selective hydrosilylation products of alkenes are of industrial importance, and the development of methods with Markovnikov selectivity is a growing area of research and still relatively rare. Herein, we have developed a convenient, transition-metal- and solvent-free method involving the alkali metal Lewis base NaOtBu as a catalyst and diphenyl silane (Ph2SiH2) as a silane reagent for the regioselective Markovnikov hydrosilylation of vinyl arenes and aliphatic alkenes in high yields with good functional group compatibility. Importantly, the hydrosilylation of allenes with Ph2SiH2 proceeds in a regioselective manner to afford (E)-allylsilane products. The utilization of the Earth-abundant sodium cation as a catalyst for hydrosilylation reactions appears to be unprecedented. We postulated the formation of a pentacoordinate silicon "ate" intermediate as evidenced by IR and mass spectrometry. Radical clock and trapping experiments support a radical mediated catalytic process. [ABSTRACT FROM AUTHOR]

Reported herein is a reactivity of propargyl alcohols as "Three‐Carbon Synthons" in a Rh(III)‐catalyzed C−H functionalization of acetanilides, leading to the synthesis of core structures of isocryptolepine, γ‐carbolines, dihydrochromeno[2,3‐b]indoles, and diindolylmethanes (DIM) derivatives. The transformation involves a rhodium(III)‐catalyzed C−H functionalization and heteroannulation to yield indoles followed by a cascade cyclization with both external and internal nucleophiles to afford diverse products. The role of the hydroxy group, the key function of the silver additive, the origin of the reverse regioselectivity and the rate‐determining step, are rationalized in conformity with the combination of experimental, noncovalent interaction analysis and DFT studies. This protocol is endowed with several salient features, including one‐pot multistep cascade approach, exclusive regioselectivity, good functional group tolerance and synthesis of variety of molecular frameworks. [ABSTRACT FROM AUTHOR]

A simple yet efficient, Hg2+ selective sensor, based on a fluroescein‐thiophene conjugate, namely, (Z)‐3′,6′‐dihydroxy‐2‐(((3‐methylthiophen‐2‐yl)methylene)amino)spiro[isoindoline‐1,9′‐xanthen]‐3‐one (FT) has been designed and synthesized. The compound was well characterized by analytical techniques such as HR‐MS, FTIR, UV‐visible absorption, steady‐state fluorescence and time‐resolved spectrophotometric techniques. Comprehensive analysis demonstrated FTas a highly specific and ultra‐sensitive sensor towards Hg2+ ions in presence of several other interfering metal ions in ethanol/H2O (9 : 1, v/v) at pH=7.2 buffered with 10 mM HEPES buffer at room temperature. The complexation of the probe FT with Hg2+ was well confirmed by ESI‐MS and FTIR spectral analysis. The detection limit of the probe FT towards Hg2+ was achieved down to 137 nM. The structure of ligand FT and FT‐Hg2+ complex were well corroborated by theoretical studies as well. In addition, the FT‐Hg2+ complex was found to be reversible in presence of di‐sodium EDTA and hence decipher its recyclability capabilities. The significance of the present probe FT lies in its successful application for the detection and quantification of Hg2+ in real water samples and logic gate fabrication for future incorporation in small organic molecule based efficient molecular devices. [ABSTRACT FROM AUTHOR]

Herein, we disclose the first report on gold‐catalyzed C(sp2)‐CN cross‐coupling reaction by employing a ligand‐enabled Au(I)/Au(III) redox catalysis. This transformation utilizes acetone cyanohydrin as a nucleophilic cyanide source to convert simple aryl and alkenyl iodides into the corresponding nitriles. Combined experimental and computational studies highlighted the crucial role of cationic silver salts in activating the stable (P,N)‐AuCN complex towards the oxidative addition of aryl iodides to subsequently generate key aryl‐Au(III) cyanide complexes. [ABSTRACT FROM AUTHOR]

A pyrene‐hydroxyquinoline tethered ingeniously designed and developed azine based Schiff base luminophoric system, 2‐((Z)‐((E)‐(pyren‐1‐ylmethylene)hydrazono)methyl)quinolin‐8‐ol (PHQ) has been explored as a selective 'TURN ON' chromofluorogenic sensor for hazardous Hg2+ ions in ethanol/H2O (9 : 1,v/v) medium with detection limit of 0.22 μM and binding constant of 1.09 x 103 M−1. The detail scrutiny of mechanism of interaction between PHQ and Hg2+ is rationalized through various techniques like 1H NMR titration, FT‐IR, mass spectral analysis, theoretical computations, Job's plot, dynamic light scattering (DLS), transmission electron microscopy (TEM), time resolved excited state decay dynamics and fluorescence reversibility studies, which concretely declare a synergistic effect of supramolecular aggregation induced enhanced emission and deactivation of photo‐induced electron transfer (PET) processes. On the other hand, a 'TURN OFF' luminescence feature of highly fluorescent PHQ hydrosol is utilized for the selective screening of powerful explosive picric acid (PA) in aqueous medium and mechanism is deciphered by means of steady state, time‐resolved emission as well as computational studies which altogether reflect a combined effect of PET and ground state complexation between probe and PA. The commendable detection limit of 55 nM and Stern‐Volmer quenching constant of 1.48 x 104 M−1 with high quenching efficiency of 84% increases the pertinency of the nano‐probe. [ABSTRACT FROM AUTHOR]

The catalyst-free regioselective [3+2]-cycloaddition of α,β-unsaturated N-arylnitrones with alkenes are developed. The series of synthetically important functionalized isoxazolidines are prepared in good to excellent yields by step economic pathway under ligand and transition-metal-free conditions. The regioselective cycloaddition pathway supported by control experiment and computational study. [ABSTRACT FROM AUTHOR]