One-step reductive amidation of nitro arenes: application in the synthesis of Acetaminophen™

A novel thioacetate mediated one-step reductive acetamidation of aryl nitro compounds was developed and applied to an efficient synthesis of acetaminophen. The reaction also proceeds well without a solvent in the presence of a catalytic amount of surfactant.     

Advancements in Gold-Catalyzed Cascade Reactions to Access Carbocycles and Heterocycles: An Overview

This review summarizes recent developments (from 2006 to 2022) in numerous important and efficient carbo- and heterocycle generations using gold-catalyzed cascade protocols. Herein, methodologies involve selectivity, cost-effectiveness, and ease of product formation being controlled by the ligand as well as the counter anion, catalyst, substrate, and reaction conditions. Gold-catalyzed cascade reactions covered different strategies through the compilation of various approaches such as cyclization, hydroarylation, intermolecular and intramolecular cascade reactions, etc. This entitled reaction is also useful for the synthesis of spiro, fused, bridged carbo- and heterocycles.     

A three-step route to a tricyclic steroid precursor

2-Alkyl cyclohexenones are useful intermediates for organic synthesis. The Wittig reaction of a series of aldehydes with (cyclopropylmethyl)triphenylphosphonium bromide delivered the corresponding alkenyl cyclopropanes. UV irradiation in the presence of Fe(CO)5 converted the alkenyl cyclopropanes to the 2-substituted cyclohexenones. This approach enabled a three-step synthesis of the tricyclic core of estrone methyl ether.     

Probing CP-violating Higgs contributions in γγ → f$$ \bar f $$

We discuss the use of fermion polarization for studying neutral Higgs bosons at a photon collider. To this aim we construct polarization asymmetries which can isolate the contribution of a Higgs boson ϕ in γγ → f , f = τ/t, from that of the QED continuum. This can help in getting information on the γγϕ coupling in case ϕ is a CP eigenstate. We also construct CP-violating asymmetries which can probe CP mixing in case ϕ has indeterminate CP. Furthermore, we take the MSSM with CP violation as an example to demonstrate the potential of these asymmetries in a numerical analysis. We find that these asymmetries are sensitive to the presence of a Higgs boson as well as its CP properties over a wide range of MSSM parameters.      

Application of Nazarov type electrocyclization to access [6,5,6] and [6,5,5] core embedded new polycycles: an easy entry to tetrahydrofluorene scaffolds related to Taiwaniaquinoids and C-nor-D homosteroids

An easy, efficient and concise approach to tetrahydrofluorene [6,5,6]ABC tricyclic core embedded new polycycles has been achieved under relatively mild and catalytic Nazarov type electrocyclization conditions, using 2 mol% of Sc(OTf)(3) in anhydrous DCM (dichloromethane) at room temperature, with high yields. The generality of the reaction has been illustrated by synthesizing diverse polycycles embedded with rare heterotricyclic [6,5,5]ABC skeletons.     

Structural landscape of benzoic acid: using experimental crystal structures of fluorobenzoic acids as a probe

Experimental crystal structures of mono and polyfluorinated benzoic acids correspond to high energy computed crystal structures of benzoic acid itself, thereby permitting access to its structural landscape.     

Exciplex formation and energy transfer in a self-assembled metal-organic hybrid system

Exciting assemblies: A metal-organic self-assembly of pyrenebutyric acid (PBA), 1,10-phenanthroline (o-phen), and Mg(II) shows solid-state fluorescence originating from a 1:1 PBA-o-phen exciplex. This exciplex fluorescence is sensitized by another residual PBA chromophore through an excited-state energy-transfer process. The solvent polarity modulates the self-assembly and the corresponding exciplex as well as the energy transfer, resulting in tunable emission of the hybrid (see figure).     

A photonic scheme for the generation of dual linear chirp microwave waveform based on the external modulation technique and its airborne application

Due to high frequency and large time bandwidth product; photonic generation and processing of arbitrary microwave waveforms has been an interesting topic in recent time. Here, a relatively new photonic technique has been proposed for the generation of a dual linear chirp microwave waveform in Ku-band. In this method two single drive Mach–Zehnder Modulators are cascaded at minimum transmission point and in push–pull mode. Theoretical analysis and simulation are developed by giving a complete mathematical model. As the result of this methodology, a dual linear chirp microwave waveform in Ku-band with relatively large bandwidth is generated. Comparative analysis is done in the present cascading technique with dual parallel Mach–Zehnder Modulator (DPMZM) technique. Range-Doppler coupling of the radar system has been investigated with the help of an ambiguity function diagram of the generated waveform. Results have analyzed through MATLAB simulation and verified by experimental results.     

Nonlinear Pulse Propagation in Unmagnetized Plasmas

Evolution of pulses for unmagnetized plasmas have been considered. By using Rayleigh-Ritz optimization method based on trial functions ordinary differential equations for the pulse parameters have been derived. It is found that the character of the pulse parameters depends on the initial wavenumber chirp.     

Guest-responsive polaritons in a porous framework: chromophoric sponges in optical QED cavities

Introducing porous material into optical cavities is a critical step toward the utilization of quantum-electrodynamical (QED) effects for advanced technologies, e.g. in the context of sensing. We demonstrate that crystalline, porous metal–organic frameworks (MOFs) are well suited for the fabrication of optical cavities. In going beyond functionalities offered by other materials, they allow for the reversible loading and release of guest species into and out of optical resonators. For an all-metal mirror-based Fabry–Perot cavity we yield strong coupling (∼21% Rabi splitting). This value is remarkably large, considering that the high porosity of the framework reduces the density of optically active moieties relative to the corresponding bulk structure by ∼60%. Such a strong response of a porous chromophoric scaffold could only be realized by employing silicon-phthalocyanine (SiPc) dyes designed to undergo strong J-aggregation when assembled into a MOF. Integration of the SiPc MOF as active component into the optical microcavity was realized by employing a layer-by-layer method. The new functionality opens up the possibility to reversibly and continuously tune QED devices and to use them as optical sensors.

A phthalocyanine-based porous material in optical cavity exhibited strong coupling and guest responsive polariton feature.