- The Acceptor Properties of some Organophosphorus(V) Bromides
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The acceptor properties of the organophosphorous(V) bromides PBr3(cat) (cat = benzene-1,2-diolate), PBr(cat)2, and PBr4Ph, and of the PBr3Ph(1+) cation, towards Lewis bases such as halide ions and uni- or bi-dentate pyridines have been investigated, mainl
- Deng, Robert M. K.,Dillon, Keith B.
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- Structure-property-reactivity studies on dithiaphospholes
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The reaction of either toluene-3,4-dithiol or benzene dithiol with phosphorus(iii) trihalides generates the corresponding benzo-fused 1,3,2-dithiaphospholes, RC6H3S2PX (R = Me (1), R = H (2); X = Cl, Br, I). The P-chloro-dithiaphospholes undergo: (a) halogen abstraction reactions with Lewis acids forming phosphenium cations; (b) substitution with LiHMDS base and; (c) reduction chemistry with sodium metal to generate the P-P σ-bonded dimer, (RC6H3S2P)2. Reduction catalysis of aldehydes with pinacolborane using dithiaphospholes is compared with their dioxaphosphole and diazaphosphole counterparts as pre-catalysts, revealing interesting differences in the reactivity of this series of compounds.
- Ould, Darren M. C.,Tran, Thao T. P.,Rawson, Jeremy M.,Melen, Rebecca L.
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p. 16922 - 16935
(2019/11/26)
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- Experiments towards the formation of 1,6-dehydroquadricyclane and density functional calculations on this and related molecules
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1,6-Dibromoquadricyclane (6) was obtained from norbornadiene (11) by hydroboration, oxidation of the diol 12 to the diketone 14 and its conversion into 2,6-dibromonorbornadiene (20) using tribromodioxaphosphole 16b followed by treatment of the mixture 17/18 with potassium tert-butoxide in DMSO and photocyclization of 20. Reaction of 6 with tBuLi (2 equiv.) led to the formation of 1-bromo-6-lithioquadricyclane 7, the NMR spectra of which were observed up to 0°C. 7 did not lose LiBr to give 4, but could be trapped with H2O and chlorotrimethylsilane to give 21e (53%) and 21f (64%). Reaction of 6 with fBuLi (> 4 equiv.) gave rise to 1,6-dilithioquadricyclane (21c), whose NMR spectra could also be recorded. 21c was converted into the corresponding 1,6-disubstituted quadricyclanes with D2O (87%), chlorotrimethylsilane (92%), dimethyl sulfate (55%), methyl chloroformate (45%), iodine monochloride (62%), and p-toluenesulfonyl chloride (48%). - Density functional calculations using the B3LYP/6-31G* level of theory showed that 1,6-dehydroquadricyclane (4) is a local energy minimum in its singlet electronic state. 4 contains a unique structure with 4 condensed cyclopropane units. The parent hydrocarbons 27 and 28, hitherto unknown, are also local energy minima in their singlet electronic states.
- Glueck-Walther, Susanne,Jarosch, Oliver,Szeimies, Guenter
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p. 493 - 500
(2007/10/03)
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- Alkenyl bromides by brominative deoxygenation of ketones in one or two steps
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The conversion of ketones into alkenyl bromides is accomplished in one or two steps by 2,2,2-tribromo-2,2-dihydro-1,3,2-benzodioxaphosphole or by the dibromomethyl methyl ether prepared therefrom. Investigations of the scope and limitations provide some hints for the preparative planning and improvement.
- Von Roman,Ruhdorfer,Knorr
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p. 985 - 992
(2007/10/02)
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