A total synthesis of 11-O-methyldebenzoyltashironin

A concise total synthesis of 11-O-methyldebenzoyltashironin is reported in which oxidative dearomatization-IMDA-RCM triad constitutes the key ring forming steps, while an unorthodox DIBAL-H mediated stereo- and regioselective reductive epoxide openings and implementation of the vinyl bromide-carbonyl equivalency concept were pivotal to the success of this endeavor.     

Facile-chelating amine-assisted synthesis of β-In<Subscript>2</Subscript>S<Subscript>3</Subscript> nanostructures from a new single-source precursor derived from <Emphasis Type="Italic">S</Emphasis>-methyl dithiocarbazate

Flake-built 3D β-In₂S₃ nanostructures were synthesized by thermolysis of S-methyl dithiocarbazate–indium(III) complex precursor in hexamethylenediamine (HMDA). XRD patterns showed that the cubic phase of 3D β-In₂S₃ remained unchanged but the crystallinity was increased after annealing at 400 °C for 20 min. The products were also characterized by SEM, TEM, and EDS. Based on the experimental results, we propose that the growth of 3D nanostructures is controlled by the stability of the intermediate chelate complex made by indium(III) and solvent. The optical properties of the 3D β-In₂S₃ nanostructures were also investigated by UV–Vis and PL spectroscopy, which indicated strong quantum confinement effect.     

New iron(III) complexes with thiosemicarbazones derived from 5-methyl-3-formylpyrazole

New iron(III) complexes of 5-methyl-3-formylpyrazole thiosemicarbazone (HMPzTS) and 5-methyl-3-formylpyrazole-4-phenylthiosemicarbazone (HMPzPTS), namely [Fe(MPzTS)₂]X and [Fe(MPzPTS)₂]X respectively, where X=Cl, NO₃, SCN and ClO₄, have been synthesised and physico-chemically characterised by magnetic measurements (polycrystalline state), electronic, i.r., e.s.r. and Mössbauer spectra. All are cationic complexes containing two monoprotonic tridentate ligands with NNS donor sites and an anionic counterpart; they behave as 1:1 electrolytes in MeOH/DMF. Coordination to central iron(III) via the pyrazolyl nitrogen (²N), the azomethine nitrogen and the thiolato sulphur atom is confirmed in the complexes from i.r. data. E.s.r. data (RT & LNT) reveal the presence of a spin-paired iron(III) cation with d² _xyd² _yzd¹ _xy configuration. The ⁵⁷Fe Mössbauer spectral data (RT) are commensurate with the presence of two iron(III) spin states, the percentage of each being dependent upon the counterion of the species.     

Enhanced photocatalytic activity of ternary CuInS<Subscript>2</Subscript> nanocrystals synthesized from the combination of a binary Cu(I)S precursor and InCl<Subscript>3</Subscript>

Ternary copper indium sulfide (CIS) nanocrystals (NCs) have been synthesized by mixing of binary precursor [Cu^I(bdpa)₂][Cu^ICl₂] (1) and/or [Cu^I(mdpa)₂][Cu^ICl₂] (2) (where, mdpa and bdpa represent methyl and benzyl ester of 3,5-dimethyl pyrazole-1-dithioic acid, respectively) with InCl₃ in a low-temperature solvothermal process. The +1 oxidation state of copper and the atomic ratio Cu to S (1:2) is atomically maintained in the pyrazole-based Cu(I)–S precursor to synthesize phase pure CuInS₂. Coordinating solvents like ethylene diamine (EN) and ethylene glycol (EG) have been used in the synthesis without any surfactants. No use of external surfactants in the synthesis of CIS nanoparticles reveals that precursor acts as stabilizing agent. The synthesized nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX) studies. The optical property of the nanocrystals shows a pronounced quantum confinement effect in the particles with band gap energy ca. 1.5 eV. The formation mechanism of ternary CIS has been proposed. The pore size distributions of the particles show the average pore diameters 13.1 nm from 1 and 5.3 nm from 2. The calculated values of the specific surface area are 8.123 and 9.577 m²/g for 1 and 2, respectively. The excellent photocatalytic degradation of rose bengal (RB) and rhodamine B (RhB) was demonstrated by the porous CIS nanocrystals.

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Graphical abstract Enhanced photocatalytic activity of ternary CuInS₂ nanocrystals synthesized from the combination of a binary Cu(I)S precursor and InCl₃. Gopinath Mondal, Ananyakumari Santra, Sumanta Jana, Nimai Chand Pramanik, Anup Mondal and Pulakesh Bera

     

Facile synthesis of nanocrystalline wurtzite Cu-In-S by amine-assisted decomposition of precursors

Phase-pure ternary wurtzite Cu-In-S nanocrystals have been synthesized by a simple amine-assisted decomposition of mixed precursor complexes derived from S-methyl dithiocarbazate (SMDTC) at a relatively low temperature without using any external surfactant. The crystal phase, morphology, crystal lattice, and chemical composition of the as-prepared products were analyzed by using X-ray diffraction, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and energy-dispersive X-ray spectroscopy (EDX). The optical properties show the pronounced quantum confinement effect in nanocrystals. A possible growth mechanism has been suggested for the formation of anisotropic wurtzite Cu-In-S It is believed that a combined effect of the chelating amine and precursors containing CH₃S unit plays a key role in the formation of the metastable phase of wurtzite Cu-In-S.     

Towards the total synthesis of neurotrophically active tashironins: rapid construction of the tetracyclic core through a tandem oxidative dearomatization-IMDA reaction-RCM protocol

An exceptionally short (three step) strategy involving tandem oxidative dearomatization, intramolecular Diels-Alder (IMDA) reaction and RCM has been devised to generate the complete carbon framework present in tashironin-type sesquiterpenoid natural products.     

Construction of the 3-prenyl-4-oxa-tricyclo[4.3.1.0]dec-8-en-2-one core of caged xanthonoid natural products via tandem Wessely oxidation-intramolecular [4+2] cycloaddition

A two-step protocol based on tandem Wessely oxidation/intramolecular Diels-Alder reaction to provide general access to the 3-prenyl-4-oxa-tricyclo[4.3.1.0^3,7]dec-8-en-2-one core present in the caged Garcinia xanthonoids is demonstrated. These readily accessible tricyclic scaffolds also provide ready entry into a variety of substituted γ-lactones through a photochemical 1,3-acyl shift and decarbonylation.     

Towards the total synthesis of tashironin related allo-cedrane natural products: further exploitation of the oxidative dearomatization-IMDA-RCM triad based strategy

Synthetic studies directed towards allo-cedrane based, tashironin sibling natural products, involving some deft functional group manipulations on a preformed tetracyclic scaffold, are delineated.     

High-yield synthesis of quantum-confined CdS nanorods using a new dimeric cadmium(II) complex of S-benzyldithiocarbazate as single-source molecular precursor

A convenient solvothermal single-source route has been developed for the bulk synthesis of CdS nanorods using new air stable dimeric cadmium(II) complex of S-benzyldithiocarbazate, [Cd(PhCH₂SC(S)NHNH₂)Cl₂]₂, at a relatively low temperature. The decomposition of the precursor was made by heating at 160 °C in hexamethylenediamine (HMDA) to give amine capped CdS nanocrystals having yield ca. 90%; nano-dimensional rods are clearly visible in transmission electron microscope (TEM). The nanorods have been further characterized by X-ray diffraction (XRD), energy dispersed X-ray spectroscopy (EDX), FTIR and optical measurements. The structure of precursor was also established by single crystal X-ray crystallography.