Dialkyl heteroaroylphosphonates based on thiophene, pyrrole or furan have been prepared and their reactions with trimethyl phosphite investigated. Deoxygenation of the carbonyl groups in these heteroaroylphosphonates occurs to give carbene intermediates, which then undergo further reaction. In the case of the furan-3-oylphosphonates and those systems containing a thiophene or pyrrole ring, the major reaction pathway involves intermolecular trapping of the carbene intermediates by the trimethyl phosphite, leading to the formation of ylidic phosphonates that can be readily converted into the corresponding 1,1-bisphosphonates. However, in some furan-2-oylphosphonates the carbenes generated undergo ring-opening to initially give acyclic alkynylphosphonates which may react further to give other novel phosphorus compounds. The effects of substituents on the extent to which intermolecular trapping of the initially formed carbene competes with intramolecular rearrangement has been investigated. The latter process appears to be suppressed by a substituent at the 5-position of the furan ring, the resulting ylidic phosphonates being a rare example of an efficient intermolecular trapping of a furan-2-yl carbene.
Targeted and non-targeted forensic profiling of black powder substitutes and gunshot residue using gradient ion chromatography-high resolution mass spectrometry (IC-HRMS). Analytica Chimica Acta, 1072. pp. 1-14.
Polydentate ligands containing the bis(hydroxymethyl)phosphine unit have been reported to exhibit enhanced oxidative stability, which would make them attractive for use in 99m Tc-radiopharmaceutical imaging agents. Benzylethyl(hydroxymethyl)-phosphine, benzylbis(hydroxymethyl)phosphine and benzyldiethylphosphine were prepared in order to investigate the origin of this oxidative stability. Little evidence was found to indicate that the hydroxymethylphosphines show an enhanced level of stability, but it was demonstrated that the reaction conditions employed in their preparation generated a number of closely related by-products, which are likely to limit the usefulness of the hydroxymethylphosphines in commercial radiopharmaceutical applications.
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