Design and chemical synthesis of iodine-containing molecules for application to solar-pumped I* lasers

Research is directed toward the design and synthesis of new media for solar-pumped I* lasers. Since the most effective existing lasants are perfluoroalkyl iodides, a strategy was proposed for the development of improved materials of this type with absorption maxima at 300 nm. Absorption spectra were synthesized and measured for prototypical species containing iodine bound to boron, iron, and cobalt

Difluorocarbene transfer from a cobalt complex to an electron-deficient alkene

We report the synthesis of the trifluoromethyl cobalt(III)tetraphenylporphyrinato complex [Co(TPP)CF3], which loses fluoride upon one-electron reduction and transfers a difluorocarbene moiety to n-butyl acrylate to produce the corresponding gem-difluorocyclopropane. Catalytic CF2 transfer from Me3SiCF3 to n-butyl acrylate becomes possible when directly using the divalent cobalt(II) porphyrin catalysts in the presence of NaI

Difluorocarbene Generation from TMSCF3: Kinetics and Mechanism of NaI-Mediated and Si-Induced Anionic Chain Reactions

The mechanism of CF2 transfer from TMSCF3 ( 1 ), mediated by TBAT (2–12 mol %) or by NaI (5–20 mol %), has been investigated by in situ/stopped-flow 19F NMR spectroscopic analysis of the kinetics of alkene difluorocyclopropanation and competing TFE/c-C3F6/homologous perfluoroanion generation, 13C/2H KIEs, LFERs, CF2 transfer efficiency and selectivity, the effect of inhibitors, and density functional theory (DFT) calculations. The reactions evolve with profoundly different kinetics, undergoing autoinhibition (TBAT) or quasi-stochastic autoacceleration (NaI) and cogenerating perfluoroalkene side products. An overarching mechanism involving direct and indirect fluoride transfer from a CF3 anionoid to TMSCF3 ( 1 ) has been elucidated. It allows rationalization of why the NaI-mediated process is more effective for less-reactive alkenes and alkynes, why a large excess of TMSCF3 ( 1 ) is required in all cases, and why slow-addition protocols can be of benefit. Issues relating to exothermicity, toxicity, and scale-up are also noted.PostprintPeer reviewe

The synthesis of 1,3-Difluoro-2-methyl-4-phenylbenzene from a one-pot reaction of Difluorocarbene and 1-Phenyl-2-methylcyclobutene

Previous studies show that 1,2-disubstituted cyclobutenes can be used in reaction with difluorocarbene to produce 1,3-difluorobenzenes. A pathway to the synthesis of these types of compounds is of interest due to their presence in fluoroquinolone antibacterials, resins, and insecticides. The synthesis is unique because the fluorine atoms from the difluorocarbene are not adjacent to each other when the ring expands to a benzene ring. This study focuses on the reaction of difluorocarbene with 1-phenyl-2-methylcyclobutene, which was synthesized in one-pot in 4 steps starting from 1-phenyl-1-propyne and zirconocene dichloride

Hard to make space: improving access to privileged pharmacophores

Limited examples of the successful ring expansion of aziridines with sulfonium ylides to generate azetidines are known, but typically result in functional groups on azetidine that are not broadly useful for downstream chemistry. Described here is an investigation into the scope of this reaction including the discovery that N-activated 2-methoxy ester functionalised aziridines are not compatible with this protocol. Advances have also been made in understanding the reactivity of azirines with rhodium carbenoids to generate azetines from successful ring expansion, or N-vinylimine from ring opening. An alternative route to azetidines from the 1,3-cleavage of azabicyclo[1.1.0]butanes is described, along with a proposed route to highly functionalised azetidines with control over the absolute configuration at each step. Early success reacting a range of reagents with an azabicyclo[1.1.0]butane of moderate steric bulk has been shown, as well as early steps towards a novel azetidine 3-sulfonamide synthesis. Difluorocyclopropanation of alkenes using fluorinated acetate salts is often a slow, inefficient and energy-intensive process. Reported here is a modified protocol enabling the preparation of 1,1-difluorocyclopropanes in less than five minutes, using microwave irradiation. The new procedure is considerably faster than previously reported methods, employs easily removed, low-boiling point solvents and avoids the use of highly toxic or ozone-depleting substances. The method has been exemplified in a high-yielding synthesis of a difluoro analogue of a clinically used drug substance, and has also shown some utility in preparing 1,1-difluorocyclopropenes and as a novel procedure for the synthesis of halogenated alkyl ether esters from cyclic ethers. Other investigations into the generation and reactivity of difluorocarbene reported here include successful proof of concept experiments showing the sensitivity of allyl functionalised difluoromethylene containing compounds to palladium species to generate difluorocarbene, as well as exploratory reactions to build on methods to generate 2,2-difluoroaziridines by addition of difluorocarbene to imines

Synthesis of gold(I)-trifluoromethyl complexes and their role in generating spectroscopic evidence for a gold(I)-difluorocarbene species

We thank the Ghent University (IoF), the Special Research Fund (BOF) starting (SPN, CSJC) and advanced (SPN, KVH) grants and Research Foundation Flanders (FWO) (fellowship to SVB and grant to CSJC and KVH) for funding.Readily-prepared and bench-stable [Au(CF3)(NHC)] compounds were synthesized using new methodologies, starting from [Au(OH)(NHC)], [Au(Cl)(NHC)] or [Au(L)(NHC)]HF2 precursors (NHC = N-heterocyclic carbene). The mechanism of formation of these species was investigated. Consequently, a new and straightforward strategy for the mild and selective cleavage of a single carbon-fluorine bond from [Au(CF3)(NHC)] complexes was attempted and found to be reversible in the presence of an additional nucleophilic fluoride source. This straightforward technique has led to the unprecedented spectroscopic observation of a gold(I)-NHC difluorocarbene species.PostprintPeer reviewe

Synthesis and characterisation of potentially electrostrictive polymers

The work described in this thesis was concerned with the synthesis of electrostrictive polymers. Electrostrictive elastomers, the so-called artificial muscles, are a recent area of interest due to their potential for application in robots, smart materials and many high-technology devices. The goal of the project was with the synthesis and characterisation of novel low T(_g) polymers bearing highly polar groups in order to produce an electrostrictive effect. The approach to such novel materials was undertaken via two different routes; firstly, the free-radical ring-opening polymerisation of partially fluorinated and alkyl substituted vinyleyclopropane monomers, and secondly, the ring-opening metathesis polymerisation and copolymerisation of partially fluorinated bicyeclo[2.2.1]hept-2-ene monomers. The outcome of the work has been the development of a synthetic route to stable polar polymers with T(_g)S below room temperature

Synthesis of organic liquid crystal containing selectively fluorinated cyclopropanes

Authors thank the Chinese Scholarship Council for a studentship (ZF) and the EPSRC Mass Spectroscopy Service at Swansea for analysis.This paper describes the synthesis of a series of organic liquid crystals (LC) containing selectively fluorinated cyclopropanes at their termini. The syntheses used difluorocarbene additions to olefin precursors, an approach which proved straightforward such that these liquid crystal candidates could be efficiently prepared. Their physical and thermodynamic properties were evaluated and depending on individual structures, they either displayed positive or negative dielectric anisotropy. The study gives some guidance into effective structure property relationships for the design of LCs containing selectively fluorinated cyclopropane motifs.Publisher PDFPeer reviewe

フッ素置換遷移金属カルベン錯体を経由する含フッ素化合物の触媒的合成法

科学研究費助成事業 研究成果報告書：挑戦的萌芽研究2016-2017課題番号 : 16K1394