- Chemoselective O-methylation of N-acylated/sulfonylated tyrosine derivatives
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Methyl ethers (6a and 6b) of N-trifluoroacetyl- and N-(m-trifluoromethyl) phenylsulfonyl-6-nitro-tyrosine t-butyl ester were readily prepared by modified Mitsunobu reaction (DPPE, DIAD, MeOH). Williamson (MeI, K2CO3 or Li2CO3 or NaOH under phase transfer) and classical Mitsunobu conditions (PPh3, DEAD, MeOH) gave O,N-dimethylated derivatives (7a and 7b) as side or main products. O- versus N-selectivity in tyrosine methylation reactions depends on both pKa values and steric factors.
- Attolini, Mireille,Boxus, Thierry,Biltresse, Stéphane,Marchand-Brynaert, Jacqueline
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p. 1187 - 1188
(2007/10/03)
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- Synthesis and evaluation of RGD peptidomimetics aimed at surface bioderivatization of polymer substrates
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Several RGD peptidomimetics have been prepared, in a convergent way, from the common ortho-amino-tyrosine template (O-substituted with an anchorage-arm or a methyl group, and αN-substituted with a fluorine tag for XPS analysis), and various ω-aminoacid derivatives. The most flexible compounds have shown a biological activity similar to that of the peptide reference (RGDS) in the platelet aggregation test. The compound 16a could be fitted (by modelisation) with DMP 728 and c(RGDfV), two cyclic peptides that are good ligands of integrins. The compound 16b has been covalently fixed on the surface of a poly(ethylene terephthalate) membrane used as support for mammalian cell cultivation. Copyright (C) 1998 Elsevier Science Ltd.
- Boxus, Thierry,Touillaux, Roland,Dive, Georges,Marchand-Brynaert, Jacqueline
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p. 1577 - 1595
(2007/10/03)
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