Two new polymeric materials (polymers A and B) containing covalently bound iodine were prepared. These polymers were evaluated with respect to their possible use as radiopaque implant biomaterials--that is, materials that are visible in a noninvasive manner using routine X-ray absorption imaging techniques. Polymer A is a copolymer of methyl methacrylate (MMA) and 1 (80 and 20 mol%, respectively). Polymer B was prepared from MMA, 1, and 2-hydroxyethyl methacrylate (HEMA) (mol ratio 65:20:15, respectively). Compound 1 was synthesized from 4-iodophenol and methacryloyl chloride. The resulting polymers were characterized with GPC, DSC, NMR, and by measuring both the advancing and receding contact angles. Thrombogenicity of the polymers was determined by an in vitro thrombin generation test procedure. The maximum concentration of free thrombin was 76 +/- 1 nM for polymer A, and 64 +/- 3 nM for polymer B. The lag times (i.e., time onset of thrombin generation) were 392 seconds for polymer A and 553 seconds for polymer B. For PVC-T, which is known as a passive material, a lag time of 583 seconds was found. This indicates that polymer B is comparable to PVC-T, and more passive than polymer A. Polymer A exhibited minor activation of platelets. Polymer B did not induce platelet activation at all. The polymers exhibited, even as fibers with a diameter of ca. 0.3 mm, good radiopacity with routine imaging X-ray techniques in the clinic.(ABSTRACT TRUNCATED AT 250 WORDS)

A new deprotection procedure in the synthesis of (partially) phosphate-methylated oligodeoxynucleotides has been developed, involving treatment of fully protected DNA fragments with methanolic potassium carbonate. It is shown that base deprotection can be accomplished in potassium carbonate/methanol without affecting the methyl phosphotriesters. This methodology enables us to synthesize, both in solution and on a solid support, DNA fragments which are phosphate-methylated at defined positions. The solid phase synthesis, however, turns out to be accompanied by considerable demethylation of the phosphotriesters. It is demonstrated that this demethylation does not occur during the deprotection or work-up procedure. Furthermore, it was found that the latter side-reaction is suppressed when the standard capping procedure with acetic anhydride is included.

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Document VersionPublisher's PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication:• A submitted manuscript is the author's version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website.• The final author version and the galley proof are versions of the publication after peer review.• The final published version features the final layout of the paper including the volume, issue and page numbers. Kuijpers, W. H. A., Genderen, van, M. H. P., ... Buck, H. M. (1989). Synthesis of phosphate-methylated DNA fragments using 9-fluorenylmethoxycarbonyl as transient base protecting group. Journal of Organic Chemistry, 54(7), 1657-1664. DOI: 10.1021/jo00268a030 Link to publication Citation for published version (APA):General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights.• Users may download and print one copy of any publication from the public portal for the purpose of private study or research.• You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal ? Take down policyIf you believe that this document breaches copyright please contact us providing details, and we will remove access to the work immediately and investigate your claim.Download date: 11. May. 2018 J. Org. Chem. 1989Chem. ,54, 1657Chem. -1664 1657Merck silica gel, 230-400 mesh, was used for flash chromatography, and Whatman Magnum-9 Partisil-10 and ODs-3 columns were used for preparative HPLC.Isolation and Extraction. Fresh leaves of C. dichogamus were collected in Kenya in mid-1987 (a voucher sample has been deposited a t the herbarium in the Botany Dept., UBC). The airdried leaves (225 g) were soaked in methanol (500 mL) overnight. The methanol extract was concentrated in vacuo to a gum, water was added, and the resulting suspension was exhaustively extracted with CH2C12. Evaporation of the combined organic extracts in vacuo gave a residue, which was fractionated via silica gel flash chromatography (step gradient: CH2C12 to EtOAc) to give crude crotoxides A (1) and B (2).Crotoxide A (1). The flash fractions containing crude crotoxide A (1) were combined and further purified by silica gel preparative TLC (2:l CH2C12/EtOAc). The preparative TLC fraction containing crotoxide A was dissolved in methanol (5 mL), palladium on charcoal was added (20 mg), and the suspension was stirred at room temperature under 1 atm of hydrogen for 2 days. Filtration of t...

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