3,612 research outputs found

    Flow chemistry in Europe

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    This is an editorial for a Special Issu

    Studies in the chemistry of benzobicyclo systems

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    Reactions of tetrahalogenobenzynes with certain tertiary arylamines afford products which are derived by both 1,2- and 1,4-cyclo-addition as well as from a betaine. The tetrahalogenobenzynes and benzyne react with eneamines to give benzocyclobutene-derivatives via betaines; the tetrahalogenobenzyne derivatives are readily hydrolysed to 2-tetrahalogenophenyl cycloalkanones. 1-N-alkylamino derivatives of 5,6,7,8-tetrahalogeno-1,4-dihydronaphthalene also undergo cleavage reactions in protic media. Thus, for example, 1-N, N-dimethylamino-tetrafluorobenzobarrelene gives 2,3,4,5- tetrafluoro-k'-N, N-dimethylaminobiphenyl in high yield and 1,2,3,1- tetrafluoro-5,8-dihydro-5,8-N-(-methyl)-iminonaphthalene affords 2'- (2,3,4,5-tetrafluorophenyl)-N-methyl. pyrrole. Apparent similarities between mass spectral and thermal processes have been investigated in connection with retro-Diels-Alder reactions leading to k, 5,6,7-tetrahalogeno-isobenzofurans and 1,5,6,7-tetrafluoro- 2-methylisoindole. These derivatives are more stable than the nonhalogenated compounds. The rearrangement reactions of 1-methoxybenzobarrelene derivatives in strong acids have been studied. Various possible mechanistic pathways have been investigated by deuterium labelling methods. Benzobicyclo[3.2.1] derivatives arise via a 2-carbonium ion while a 3-carbonium ion leads to benzobicyclo[2.2.2)dien-2-one derivatives. The solvolyses of certain toluene-p-sulphonates have been used to check mechanistic predictions. The position of protonation and the extent of the rearrangement can be controlled by the use of alkyl substituents. Thus 2,6-dimethyl-l-methoxytetrafluorobenzobarrelene affords only derivatives of benzobicyclo[3.2.1]- octadiene while 3,5-dimethyl-l-methoxy-tetrafluorobenzobarrelene gives products derived by rearrangement to the benzobicyclo[2.2.2] system

    The Evolution of Flow Chemistry: An Opinion on Factors Driving Innovation

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    This article seeks to provide an overview of the environmental factors within the pharmaceutical industry that have contributed to the emergence of flow chemistry over the past two decades. It highlights some of the challenges facing the industry and describes how they are being overcome by the exponential trajectory of scientific progress in the area. We identify current trends and offer a speculative glimpse into the future of drug development and manufacturing with some examples of progress being made at CARBOGEN AMCIS

    A multistep continuous flow synthesis machine for the preparation of pyrazoles via a metal-free amine-redox process.

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    A versatile multistep continuous flow setup is reported for the four-step conversion of anilines into pyrazole products. The synthesis machine incorporates the use of amine-redox chemistry through diazotization and a metal-free vitamin C mediated reduction. The machine can be used for the synthesis of an array of analogues or the scale up of an individual target.We are grateful to the Cambridge Home and European Scholarship Scheme (JSP) and EPSRC (DLB and SVL, grant numbers EP/K0099494/1 and EP/K039520/1) for financial support.This is the final version of the article. It first appeared from the Royal Society of Chemistry via http://dx.doi.org/10.1039/C5RE00082

    Enabling Technologies for the Future of Chemical Synthesis.

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    Technology is evolving at breakneck pace, changing the way we communicate, travel, find out information, and live our lives. Yet chemistry as a science has been slower to adapt to this rapidly shifting world. In this Outlook we use highlights from recent literature reports to describe how progresses in enabling technologies are altering this trend, permitting chemists to incorporate new advances into their work at all levels of the chemistry development cycle. We discuss the benefits and challenges that have arisen, impacts on academic-industry relationships, and future trends in the area of chemical synthesis.We are grateful to the Woolf Fisher Trust (D.E.F), Syngenta Crop Protection AG (C.B.) and EPSRC (S.V.L., grant codes EP/K009494/1, EP/M004120/1 and EP/K039520/1) for financial assistance.This is the final version of the article. It first appeared from the American Chemical Society via https://doi.org/10.1021/acscentsci.6b0001
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