Synthetic routes to thiazoloindoles

Several structural types of thiazoloindoles can be distinguished with regard to the position of the fusion between the thiazole, benzene, and pyrrole rings. The present review describes the synthetic routes to five selected types of thiazoloindole derivatives with [3,2-a], [3,4-a], [5,4-b], [5,4-e], and [4,5-e] fusion. These compounds are useful for the discovering of future targets and the development of new drug molecules.     

Synthetic routes to imidazothiazines

This review article presents the available synthetic routes for the preparation of different types of imidazothiazines. Imidazothiazines dealt with are classified into five types based on the position of linkage between imidazole and thiazine rings. The importance of the latter compounds in pharmacology is also discussed. The main purpose of this review is to present a survey of literature on imidazothiazines and provide useful and up-to-date data to organic and medicinal chemist, since such compounds have not been reviewed before.     

Solvent-free palladium-catalyzed addition of diaryl dichalcogenides to alkynes

Solvent-free palladium-catalyzed addition of diaryl disulfides and diselenides to terminal alkynes makes it possible to achieve high stereoselectivity and almost 100% yields in 10 min using only 0.1 mol.% catalyst. Both Pd(PPh₃)₄ and easily available Pd(OAc)₂ and PdCl₂ can be used in the reaction with an excess of triphenylphosphine. The catalyst and triphenylphosphine are readily recycled for repeated use. The study of the mechanism of the solvent-free catalytic reaction indicates that the process involves binuclear palladium complexes.     

Gel routes to environmental catalysts

Various methods for the preparation of metal oxide catalysts for environmental control purposes are described. These include coprecipitation, sol-gel, and impregnation, and are used to prepare mixed oxide catalysts of the types SnO₂-MO₂ (M=Ce or Zr), SnO₂-Ln₂O₃ (Ln = lanthanide), Ln-doped CeO₂, Cr (VI)-doped SnO₂, and Cu(II)-doped SnO₂. The aggregation in stable colloidal sols of SnO₂, CeO₂ and ZrO₂ is dependent on the concentration of the metal oxide. Techniques for the characterisation of these catalyst materials include gas adsorption, X-ray diffraction, and TEM/EDXA.     

Interfacial routes to colloidal gelation

Colloidal gelation is a rheological transition from fluid-like to solid-like viscoelasticity in a particulate suspension and is often instigated by causing the net interparticle interaction to be attractive. In this article, three routes to colloidal gelation that have been discovered recently and involve interfacial phenomena at a fluid interface are reviewed. As in conventional systems, gelation is due to a percolating particle network that imparts elasticity to the mixture, but the network formation involves interfacial particle jamming or bridging, or capillary interactions along or across interfaces, in a mixture of immiscible fluids. Gelation imparts mechanical stability to these multiphase mixtures and paves the way for their use as templates for the synthesis of functional, microstructured materials and composites. The gel mechanical properties are mediated by the interfacial forces and the mixture's microstructure, and therefore show different dependencies on particle volume fraction across the three systems.     

Synthetic routes to 5,10,15-triaryl-tetrabenzocorroles

Two different synthetic routes for the preparation of 5,10,15-triaryl-tetrabenzocorroles have been developed. The first approach is based on the condensation of a tetrahydroisoindole with aryl-aldehydes, and the second pathway involves a cross-coupling reaction between a bromo-substituted corrole and a suitable substrate to form the four β-fused aryl rings. These routes are successful to lead to the target tetrabenzocorroles, obtained in both cases as the corresponding Cu complex and with the highest yield obtained via the one-step cross-coupling methodology. Demetalation of the Cu-tetrabenzocorrole produces the corresponding free base; this macrocycle was further exploited to obtain the Sn and Co complexes in good yields.     

Facile routes to alkyl-BIAN ligands

The Alkyl-BIAN ligands tert-Butyl-BIAN and 1-Adamantyl-BIAN have been synthesized and their structures have been determined by single-crystal X-ray diffraction along with that of the ZnCl2 complex of tert-Butyl-BIAN.     

Transition metal-mediated routes to cyclopentenones

Cyclopentenones are not only key building blocks for organic synthesis, but many possess interesting biological properties in their own right. This review begins with an overview of the biological importance of cyclopentenones and a summary of the main classical routes to cyclopentenones. A detailed account of recent advances in transition metal-mediated approaches to cyclopentenones follows. The aim of the review is to draw attention to transition metal-mediated approaches to cyclopentenones that are starting to be applied in organic synthesis, and to highlight promising cyclopentenone-forming reactions that have not yet realised their full potential in a synthetic context.     

Rational routes to formyl-substituted chlorins

Two distinct approaches have been developed for the synthesis of chlorins bearing formyl groups: (1) reaction of an acetal-substituted 1-acyldipyrromethane with 2,3,5,6-tetrahydro-1,3,3-trimethyldipyrrin to give upon hydrolysis a 5-formylchlorin and (2) Pd-mediated coupling of a bromochlorin with a one-carbon synthon (hydroxymethyl tributyltin or CO) to give a 13-, 15-, or 3,13-formylchlorin. The zinc chlorins exhibit long-wavelength peak absorption maxima ranging from 626 to 667 nm, indicating the wavelength tunability afforded by formyl substitution.     

Simple synthetic routes to geiparvarin

Starting from geranyl acetate, efficient routes to 3(2H)-furanone derivatives via allylic oxidation and cyclization are described which have been utilized in the synthesis of a naturally occurring antitumor agent, geiparvarin.     

Synthetic routes to cyclopropylidenecarbinols and to cyclopropylidienes

Functionalized alkylidine cyclopropanes have beeen prepared from 1-seleno 1-vinyl cyclopropanes using [2,3] sigmatropic rearrangement of their corresponding selenonium ylides. A comparison with sulphur analogues is presented.     

偕二酸酯的无溶剂合成

以醛和酸酐为原料,溴化锌为催化剂,无溶剂条件下高产率地合成了偕二酸酯(其中醛与苯甲酸酐的反应是首次报道)。部分产物的结构经NMR,IR和MS表征。     

Solvent-free luminescent organic liquids

Illuminating! Isolation of a π-core by covalently attached flexible hydrocarbon chains has been employed to synthesize blue-emitting oligo(p-phenylenevinylene) (OPV) liquids with tunable viscosity and optical properties. A solvent-free, stable, white-light emitting ink/paint, which can be applied onto various surfaces and even onto LEDs, was made by blending of liquid OPVs with emissive solid dopants.     

Solvent-free synthesis of ferrocenylimines

The mixing of equimolar quantities of ferrocenylaldehydes and aromatic amines in a solvent-free environment provided excellent yields of ferrocenylimines. After mixing the aldehydes and amines, a melt formed which eventually solidified to the product. An analytically pure sample of the product was obtained by cold recrystallization. 2004 Elsevier Science B.V. All rights reserved.     

Template-free routes to porous inorganic materials

New approaches to solid-state reactivity have allowed us to develop unusual routes to porous inorganic materials. This article describes our recent work on template-free routes involving the selective leaching of one phase from a two-phase composite to form porous oxides. Subsequent reactions have been developed to yield porous metals, conformal coatings, and hierarchically porous materials. Pores can also be generated through simple redox processes in transition-metal oxides; such redox cycling allows mesopores to be produced in a regenerative process in a material which is already macroporous.