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Synthesis of 11C-labelled N,N’-diphenylurea and ethyl phenylcarbamate by rhodium-promoted carbonylation reaction via [11C]-isocyanatobenzene using phenyl azide and [11C]carbon monoxide
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Biochemistry and Organic Chemistry.
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2004 (English)In: Organic and biomolecular chemistry, ISSN 1477-0520, E-ISSN 1477-0539, Vol. 2, no 21, 3063-3066 p.Article in journal (Refereed) Published
Abstract [en]

The reaction with phenyl azide and [11C]carbon monoxide to give N,N'-diphenyl[11C]urea and ethyl phenyl[11C]carbamate has been studied with the aim of development of a new methodology for carbonylation using [11C]carbon monoxide with high specific radioactivity. The synthesis of 11C-labelled N,N'-diphenylurea from phenyl azide and [11C]carbon monoxide, with 1,2-bis(diphenylphosphino)ethane-bound Rh(I) complex at 120 degrees C at a pressure of 35 MPa in the presence of aniline was accomplished in 82% trapping efficiency and 82% conversion yield. This approach was also useful for the synthesis of ethyl phenyl[11C]carbamate with lithium ethoxide as a nucleophilic reagent giving 90% trapping efficiency and 76% conversion yield. These reactions can be considered to proceed via a [11C]isocyanate or a [11C]isocyanate-coordinated Rh complex to give the corresponding 11C-products. This protocol provides the chemical basis for the synthesis of [11C]urea and [11C]carbamate derived from [11C]isocyanates.

Place, publisher, year, edition, pages
2004. Vol. 2, no 21, 3063-3066 p.
National Category
Natural Sciences
URN: urn:nbn:se:uu:diva-94170DOI: 10.1039/B409294EPubMedID: 15505707OAI: oai:DiVA.org:uu-94170DiVA: diva2:167930
Available from: 2006-04-07 Created: 2006-04-07 Last updated: 2013-09-18Bibliographically approved
In thesis
1. [11C]Carbon Monoxide in Rhodium-/Palladium-Mediated Carbonylation Reactions
Open this publication in new window or tab >>[11C]Carbon Monoxide in Rhodium-/Palladium-Mediated Carbonylation Reactions
2006 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Methods for the 11C-labeling of carbonyl compounds applicable in the preparation of radiotracers for Positron Emission Tomography (PET) are described. To this end [11C]carbon monoxide at low concentration was used in transition metal- mediated reactions.

Stille couplings were employed in the synthesis of [carbonyl-11C]ketones from methyl and aryl halides with [11C]carbon monoxide. The synthesized [carbonyl-11C]ketones were obtained from the corresponding organostannanes with analytical radiochemical yields up to 98%.

A number of synthetic routes were designed using [11C]carbon monoxide and rhodium complexes. Nitrene intermediates were generated from azides and reacted via a rhodium-mediated carbonylation reaction as a general synthetic route to [carbonyl-11C]isocyanates, versatile precursors. [carbonyl-11C]Isocyanate reacted via nucleophilic attack of an amine to form N,N’-diphenyl[11C]urea in 82% analytical radiochemical yield, ethyl phenyl[11C]carbamate was synthesized by the same route, using ethanol as the nucleophile, in 70% radiochemical yield. [11C]Isocyanate was also able to react in a [2+3] cycloaddition with ethylene oxide to form 3-phenyl[carbonyl-11C]oxazolidin-2-one in over 80% analytical radiochemical yield. This method was applied to the synthesis of a potential efflux system tracer [11C]hydroxyurea in 38% isolated radiochemical yield and the derivative 1-hydroxy-3-phenyl[11C]urea in 35% isolated radiochemical yield. Carbene intermediates, generated from diazo compounds, were reacted with [11C]carbon monoxide in the rhodium-mediated synthesis of [carbonyl-11C]ketenes. [carbonyl-11C]Ketene intermediates were utilised in the synthesis of diethyl[carbonyl-11C]malonate, from ethyl diazoacetate and ethanol. The product was obtained with a 20% isolated radiochemical yield. Alkylation of diethyl[carbonyl-11C]malonate, with ethyliodide and tetrabutylammonium fluoride, was successfully accomplished and diethyl diethyl[carbonyl-11C]malonate was synthesized in 50% analytical radiochemical yield. Several (carbonyl-13C)compounds were also synthesized using the described methods as a way of characterizing the position of the label using 13C-NMR.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2006. 50 p.
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 156
Organic chemistry, carbonylation reaction, carbon monoxide, PET, 11C-labelling, rhodium, palladium, Organisk kemi
National Category
Organic Chemistry
urn:nbn:se:uu:diva-6654 (URN)91-554-6500-5 (ISBN)
Public defence
2006-04-28, Room B22, BMC, Husarsgatan 3, Uppsala, 09:00
Available from: 2006-04-07 Created: 2006-04-07Bibliographically approved

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