New reactions and reactive intermediates in the pyrolysis of cyclic phosphonium ylides
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Pyrolysis, either neat or in diphenyl ether solution, results in the conversion of both 4-triphenylphosphoranylidenetetrahydrofuran-2,3,5-trione and 4-triphenylphosphoranylidenetetrahydrothio-phene-2,3,5-trione into 3,5-bis(triphenylphosphoranylidene)cyclopentane-1,2,4-trione. These reactions involve extrusion of CO2 or COS to give 3-triphenylphosphoranylidenecyclopropane-1,2-dione which further loses CO to give triphenylphosphoranylideneketene. The precise way in which these two reactive phosphorus compounds combine to give the observed product has been examined by chemical and isotopic labelling studies. Cyclotrimerization of triphenylphosphoranylideneketene upon thermolysis in diphenyl ether has also been observed for the first time. The erroneous literature interpretation of the 13C NMR spectrum for triphenylphosphoranylideneketene is corrected.
Aitken , R A , Bjornstad , V , Massil , T , Skramstad , J & Young , R J 2017 , ' New reactions and reactive intermediates in the pyrolysis of cyclic phosphonium ylides ' ARKIVOC , vol 2017 , no. iii , pp. 293-301 . DOI: 10.24820/ark.5550190.p010.208
© ARKAT USA, Inc. 2017. This is an open access article published under a Creative Commons Attribution-NonCommercial 4.0 International licence (CC BY-NC 4.0) - https://creativecommons.org/licenses/by-nc/4.0/
DescriptionThe authors are grateful to EPSRC and Glaxo-Wellcome (now GSK) for their support of this work through a CASE Studentship to TM.
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