Reaction of Acyl Chlorides with In Situ Formed Zinc Selenolates: Synthesis of Selenoesters versus Ring-Opening Reaction of Tetrahydrofuran

Attempting to apply thein situproduction of PhSeZnSePh to the synthesis of selenoesters, an unexpected reaction involving the solvent (tetrahydrofuran) was observed and studied. We reported here some evidences about the mechanism and the possibility to control the chemoselectivity of this new reaction that afforded the formation of interesting selenoderivatives in which the selenium moiety and the carboxylic one are spaced by four carbon units

highlight on the reactivity of phseznx

The first bench stable selenolates, PhSeZnHalides have been synthesized through a completely atom economy oxidative insertion of the elemental zinc on the commercially available PhSeHalides. These reagents showed the characteristic nucleophilic reactivity which will be reviewed in this report. All of the reactions were strongly accelerated when effected in water suspension. Alkyl, aryl, vinyl and acyl substitutions, ring-opening reactions of epoxides and aziridines and Michael type addition will be described including the role of the zinc in the control of the chemoselectivity and stereoselectivity

ultrasound mediated synthesis of ecofriendly zinc chalcogenates in on water conditions

Nucleophilic Selenium is a convenient strategy for the functionalization of organic substrates having electrophilic character. Among all the methods developed for their preparation, the reduction of the corresponding diselenides represents the most versatile procedure. Using these protocols selenolates were usually prepared in situ using atom expensive reducing agents such as NaBH4, LiAlH4, or metals (Na, Li) or metal hydride (NaH). We recently reported that zinc can be efficiently used to reduce Se-halogen bond affording bench stable regents such as PhSeZnCl that showed a strong rate acceleration in "on water" conditions for a number of reactions: alkyl, aryl, vinyl and acyl substitutions, ring-opening reactions of epoxides and aziridines and Michael type addition. We report now the use of Ultrasound irradiation for the oxidative insertion of zinc into Se-Se bond and the formation of the nucleophilic reagent PhSeZnSePh as a green strategy to avoid the use of useless halogen and increase the atom economy of the selenenylating species

“Green Is the Color”: An Update on Ecofriendly Aspects of Organoselenium Chemistry

Organoselenium compounds have been successfully applied in biological, medicinal and material sciences, as well as a powerful tool for modern organic synthesis, attracting the attention of the scientific community. This great success is mainly due to the breaking of paradigm demonstrated by innumerous works, that the selenium compounds were toxic and would have a potential impact on the environment. In this update review, we highlight the relevance of these compounds in several fields of research as well as the possibility to synthesize them through more environmentally sustainable methodologies, involving catalytic processes, flow chemistry, electrosynthesis, as well as by the use of alternative energy sources, including mechanochemical, photochemistry, sonochemical and microwave irradiation

Ultrasound-promoted synthesis of 2-organoselanyl-naphthalenes using Oxone® in aqueous medium as an oxidizing agent

A green methodology to synthesize 2-organoselanyl-naphthalenes based on the reaction of alkynols with diaryl diselenides is described. The electrophilic species of selenium were generated in situ, by the oxidative cleavage of the Se–Se bond of diaryl diselenides by Oxone® using water as the solvent. The reactions proceeded efficiently under ultrasonic irradiation as an alternative energy source, using a range of alkynols and diorganyl diselenides as starting materials. Through this methodology, the corresponding 2-organoselanyl-naphthalenes were obtained in moderate to good yields (56–94%) and in short reaction times (0.25–2.3 h)

Synthesis of diaryl selenides using electrophilic selenium species and nucleophilic boron reagents in ionic liquids

We described herein the use of imidazolium ionic liquids [bmim]PF(6) and [bmim]BF(4) in the selective, metal and catalyst-free synthesis of unsymmetrical diaryl selenides by electrophilic substitution in arylboron reagents with arylselenium halides (Cl and Br) at room temperature. This is a general substitution reaction and it was performed with arylboronic acids or potassium aryltrifluoroborates bearing electron-withdrawing or electron-donating groups, affording the corresponding diaryl selenides in good to excellent yields. The ionic liquid [bmim][PF(6)] was easily recovered and utilized for further substitution reactions.FAPERGS[FAPERGS/PRONEX 10/0005-1]FAPERGS[10/0027-4]Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)FINEPCNP

Synthesis of Fused 1,2,3-Triazoyl-1,3,6-triazonines through Copper-Catalyzed Intramolecular Ullmann Cross-Coupling Reaction

© 2016 Elsevier Ltd We describe here an efficient method to synthesize 1-aryl-15H-dibenzo[d,h][1,2,3]triazolo[1,5-a][1,3,6]triazonines by copper-catalyzed intramolecular Ullmann cross-coupling reaction. Reactions between a range of 5-iodo-1,2,3-triazoyl benzaldehydes and substituted diaminobenzenes in the presence of a catalytic amount of CuI (5 mol %) in DMSO at 100 °C under microwave irradiation have proven to be an efficient way to access new fused 1,2,3-triazolo-1,3,6-triazonines in good to excellent yields.status: publishe

Total synthesis of (+/-)-dihydroactinidiolide using selenium-stabilized carbenium ion

A new, short total synthesis of dihydroactinidiolide 1 is described using selenium carbenium ion-promoted carbon-carbon bond formation as the key step. Our synthetic strategy starts with a lactonization reaction between 1,3,3-trimethylcyclohexene 13 and alpha-chloro-alpha-phenylseleno ethyl acetate 14, affording the key intermediate, alpha-phenylseleno-gamma-butyro lactone 15, which reacted via a selenoxide elimination to the target compound 1. (C) 2009 Elsevier Ltd. All rights reserved.FAPESPCAPESFAPERGSFUNDECT-MSCNP

Sweet Selenium: Synthesis and Properties of Selenium-Containing Sugars and Derivatives

In the last decades, organoselenium compounds gained interest due to their important biological features. However, the lack of solubility, which characterizes most of them, makes their actual clinical exploitability a hard to reach goal. Selenosugars, with their intrinsic polarity, do not suffer from this issue and as a result, they can be conceived as a useful alternative. The aim of this review is to provide basic knowledge of the synthetic aspects of selenosugars, selenonium salts, selenoglycosides, and selenonucleotides. Their biological properties will be briefly detailed. Of course, it will not be a comprehensive dissertation but an analysis of what the authors think is the cream of the crop of this interesting research topic