Gérard Sennyey

Pentaalkylguanidines as etherification and esterification catalysts

Abstract Several pentaalkylguanidines have been prepared and found to be superior catalysts for the preparation of aryl and aralkyl ethers from carbonates and for the methylation of phenols with dimethylcarbonate. They also act as effective catalysts for esterification of acids with alkyl chloroformates but not for the acetylation of tertiary alcohols with acetic anhydride.

Amino acid fluorides : their preparation and use in peptide synthesis

Abstract Z or Fmoc amino acid fluorides have been prepared from the protected amino acids and cyanuric fluoride, and have been tested both in the condensation with simple amino acid esters and in Solid Phase Peptide Synthesis.

Grafting of 2-vinyl-4,4-dimethylazlactone onto electron-beam activated poly(propylene) films and fabrics. Application to the immobilization of sericin†

The grafting of 2-vinyl-4,4-dimethylazlactone (VDM) onto electron-beam activated poly(propylene) (PP) films and fabrics and subsequent reaction of the anchored azlactone groups with various nucleophiles was investigated. Surface graft polymerization was demonstrated by FTIR and X-ray photoelectron spectroscopy (XPS) analysis. Determination of azlactone loading of the PP-g-VDM films and fabrics was achieved by titration. It was confirmed that grafted poly(VDM) chains are reactive towards nucleophiles such as water, benzylamine, Jeffamine M600®, and poly- (β-benzyl aspartate) ω-benzylamide used as a model of peptidic chain. Sericin, a natural water-soluble protein issued from silk degumming, was immobilized onto PP-g-VDM fabrics. Mass uptake up to 10% was obtained at room temperature using the raw solution resulting from industrial degumming process. Immobilization of sericin onto PP-g- VDM fabrics was assessed by FTIR, XPS, and determination of amino acid content after acidic hydrolysis. The results suggest that this technique is useful for obtaining permanent altered surfaces and that PP-g-VDM films and fabrics could be used for deproteinization of aqueous solutions as well as in the field of combinatorial chemistry as scavengers or substrates.

Synthesis and use of dibenzylpyrocarbonate: preparation of dipeptide free N-benzyloxycarbonyl glycine

Le dicarbonate de benzyle synthetise reagit avec les glycine, valine, alanine et leucine en donnant les N-benzyloxycarbonyl α-aminoacides correspondants

Diallyl dicarbonate: a convenient reagent for the synthesis of allyl carbamates

Abstract Diallyldicarbonate was prepared and used for the amino protection of various compounds including amino acids, amino sugars and nucleosides.

New polyurethanes derived from amino acids: Synthesis and characterization of α,ω-diaminooligopeptides by ring-opening polymerization of glutamate N-carboxyanhydrides

Abstract Strictly aminotelechelic oligopeptides with γ-methylglutamate or γ-benzylglutamate units were synthesized by oligomerization of the corresponding N-carboxyanhydride initiated by ethylenediamine. The degree of polymerization (DP) was controlled by the ratio of NCA to ethylenediamine concentrations for reaction times of less than 1 h and DP=20. The aminotelechelic nature, which greatly depends on the conditions used during oligomerization, was confirmed by amino end-group quantification. Characterization was achieved by 1 H and 13 C NMR and IR spectroscopy.

2,2'-Carbonyl-bis(3,5-dioxo-4-methyl-1,2,4-oxadiazolidine). I: A new reagent for the preparation of carbamates and amides, application to the synthesis of dipeptides

Abstract 2,2′-Carbonyl bis(3,5-dioxo-4-methyl-1,2,4-oxadiazolidine) was prepared and used for the synthesis of various carbamates and dipeptides.

Simple, inexpensive routes to E and Z zeatine ribosides and derivatives useful for immunoassay.

Allylic oxidation of 6-N-(3,3-dimethylallyl)adenosine 1 gave trans (E) zeatine riboside 3, which was isomerized to the cis (Z) isomer 5 by u.v. irradiation. A method for the regiospecific 3′-O-succinoylation of these nucleosides is given.

Syntheses of the two epimeric 5′-methylcytidines, their 5′-phosphates and [5-3H]-5′-pyrophosphates, and the two 5′-methyldeoxycytidines. A novel cystosine anhydro-nucleoside with two oxygen bridges between the base and the sugar

In a series of experiments the starting materials were methyl 2,3-O-isopropylidene-β-D-alto- and -α-L-talofuranosides. These were converted in two steps into the corresponding 2,3,5-tri-O-benzoyl esters, (5) and (11), which were coupled with N-acetylbis(trimethylsilyl)cytosine in the presence of tin(IV) chloride, to the protected nucleosides (19) and (20). Alkaline methanolysis gave the free cytidine homologues, 1-(6-deoxy-β-D-alto- and -α-L-talo-furanosyl)cytosine (23) and (28), which were converted into the crystalline 5′-phosphates (24) and (29), and hence to the dilithium salts of the 5′-pyrophosphates, (25) and (30), by standard procedures. These were labelled at C-5 by bromination, followed by catalytic reduction in tritium gas. The same methyl furanoside starting materials were converted into the 3,5-dibenzoates, (3) and (9), by deacetalation followed by monobenzoylation by the stannylene procedure. Substitution of iodine via the 2-trifluoromethanesulphonates gave iodides which were reduced by tributylstannane to methyl 3,5-di-O-benzoyl-2,6-dideoxy-β-D-ribo- and -α-L-lyxo-hexofuranosides (7) and (13). Coupling of these in the same way as above, followed by alkaline methanolysis, gave the two deoxycytidine homologues, 1-(2,6-dideoxy-β-D-ribo- and -α-L-lyxo-hexofuranosyl)cytosine, (16) and (17), together with their anomers (14) and (15). In another approach to these nucleosides, 4-N-acetyl-2′,3′-O-isopropylidenecytidine was oxidized to the aldehyde (33) which was condensed with dimethylsuiphoxonium methylide to a mixture of epoxides (34) and (35). Hydrogen bromide opening, followed by tributylstannane reduction, converted these epoxides into 4-N-acetyl-1-(2,3-O-isopropylidene-6-deoxy-β-D-allo- and -α-L-talo-furanosyl)cytosine (36) and (37). Treatment of the same mixture dissolved in tetrahydrofuran (THF) by boron trifluorideether gave 4-acetamido-1-(2,5′; 2,6′-dianhydro-2′,3′-O-isopropylidene-α-L-talofuranosyl)-2H-pyrimidine (39), the first reported anhydro-nucleoside with two oxygen bridges between the base and the sugar, available in 18% overall yield from protected cytidine.

2,2'-Carbonyl-bis(3,5-dioxo-4-methyl-1,2,4-oxadiazolidine). II: Reagent for the direct esterification of carboxylic acids

Abstract Reaction of carboxylic acids including N-protected α-amino acids with 2,2′-carbonyl bis(3,5-dioxo-4-methyl-1,2,4-oxadiazolidine) and alcohols affords the corresponding esters under mild conditions.