Green synthesis and antioxidant activity of new PEGylated ferulic acids

in Tetrahedron Letters (2012), 53(19), 2402-2405

PEGylation of ferulic acid is described through a green esterification process involving poly(ethylene glycol) (PEG) with three different average molecular weights (200, 400 and 1000 g/mol) as both ... [more ▼]

PEGylation of ferulic acid is described through a green esterification process involving poly(ethylene glycol) (PEG) with three different average molecular weights (200, 400 and 1000 g/mol) as both reactive and solvent. Esterification with PEG400 and PEG1000 leads to original compounds soluble in all proportions in water. These new compounds display an antioxidant activity similar to that of ferulic acid. [less ▲]

Fast production of highly concentrated reactive [18F] fluoride for aliphatic and aromatic nucleophilic radiolabelling

in Tetrahedron Letters (2010), 51

The use of a polymeric solid support loaded with a long alkyl chain quaternary ammonium allows the rapid and efficient recovery of cyclotron produced [18F]F- from [18O]water to a low water content organic ... [more ▼]

The use of a polymeric solid support loaded with a long alkyl chain quaternary ammonium allows the rapid and efficient recovery of cyclotron produced [18F]F- from [18O]water to a low water content organic solution compatible with fast nucleophilic labelling of most precursors for PET radiopharmaceuticals in high yield. [less ▲]

Imidazol(in)ium carboxylates as N-heterocyclic carbene ligand precursors for Suzuki-Miyaura reactions

in Tetrahedron Letters (2006), 47(48), 8529-8533

Simple catalysts formed in situ from palladium acetate and a variety of imidazolium and imidazolinium carboxylates and dithiocarboxylates have been screened in the coupling of aryl halides with trans-2 ... [more ▼]

Simple catalysts formed in situ from palladium acetate and a variety of imidazolium and imidazolinium carboxylates and dithiocarboxylates have been screened in the coupling of aryl halides with trans-2-phenylvinylboronic acid. Imidazol(in)ium carboxylates show an excellent activity, which compares to that displayed by the parent imidazol(in)ium chlorides, whereas imidazol(in)ium dithiocarboxylates are poorly efficient. Interestingly, the base employed exerts a profound influence on the trans/cis stereochemistry of the coupling product. (c) 2006 Elsevier Ltd. All rights reserved. [less ▲]

A Chemoselective Ligation For The Synthesis Of Amino Acid Derivatives Of Virginiamycin M-1

in Tetrahedron Letters (2005), 46(43),

Formation of upper rim acylated calix[4]arenes using a sacrifici al zinc anode

in Tetrahedron Letters (2005), 46(44), 7499-7502

A straightforward electrosynthetic method is described, which allows upper rim acylation of non-p-halogenated calix[4]-arenes. For example, a solution of tetrapropoxycalix[4]arene 4 was electrolysed in ... [more ▼]

A straightforward electrosynthetic method is described, which allows upper rim acylation of non-p-halogenated calix[4]-arenes. For example, a solution of tetrapropoxycalix[4]arene 4 was electrolysed in the presence of ZnBr2, in an undivided cell fitted with a sacrificial zinc anode using pure acetonitrile as solvent, yielding an organozinc species, which was then treated with acetyl chloride in the presence of a palladium catalyst to afford 5,11-diacety1-25,26,27,28-tetrapropoxycalix[4]arene 5 in ca. 35% yield after workup. (c) 2005 Elsevier Ltd. All rights reserved. [less ▲]

New 1-alk(en)yl-1,3,5-trihydroxycyclohexanes from the Dufour gland of the African ant Crematogaster nigriceps

in Tetrahedron Letters (2003), 44(7), 1383-1386

The Dufour gland of the African ant Crematogaster nigriceps contains a mixture of at least eight 1-heptadec(en)yl- and 1-nonadec(en)yl-1,3,5-trihydroxycyclohexane derivatives, the mono-unsaturated ... [more ▼]

The Dufour gland of the African ant Crematogaster nigriceps contains a mixture of at least eight 1-heptadec(en)yl- and 1-nonadec(en)yl-1,3,5-trihydroxycyclohexane derivatives, the mono-unsaturated components being the major ones (about 65%). They are accompanied by small amounts of (Z,Z)-dienic derivatives (<10%). The structures, the relative and absolute configurations, and the preferred conformation of these new compounds have been established by spectroscopic and chemical methods, whereas the positions of the double bond in the alkenyl chains were determined by DMDS derivatisation followed by linked scan EIMS. [less ▲]

Strychnohexamine from Strychnos icaja, a naturally occurring trimeric indolomonoterpenic alkaloid

in Tetrahedron Letters (2002), 43(18), 3387-3390

A reinvestigation of Strychnos icaja roots has resulted in the isolation, from the EtOAC extract, of one tertiary trisindole alkaloid, named strychnohexamine. Its structure has been investigated by means ... [more ▼]

A reinvestigation of Strychnos icaja roots has resulted in the isolation, from the EtOAC extract, of one tertiary trisindole alkaloid, named strychnohexamine. Its structure has been investigated by means of spectroscopic data interpretation (UV. IR. HRESIMS. 1D and 2D NMR). This is the first time that a natural trimeric indolomonoterpenic alkaloid has been isolated directly from a plant species. This compound is one of the largest alkaloids ever discovered. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

A biomimetic synthesis of coelenterazine analogs

in Tetrahedron Letters (2002), 43(17), 3161-3164

N-(Trifluoroacetyl)dehydrodipeptides 2–3 were coupled to aminomethylene dimethylacetal derivatives 4–5. The resulting pseudo-tripeptides 6 were stepwise deprotected (carbonyl function (7) then amine ... [more ▼]

N-(Trifluoroacetyl)dehydrodipeptides 2–3 were coupled to aminomethylene dimethylacetal derivatives 4–5. The resulting pseudo-tripeptides 6 were stepwise deprotected (carbonyl function (7) then amine function) and in situ cyclized into imidazolopyrazines 1. [less ▲]

Electrophile induced rearrangement of 1-alkynylaluminium ate complexes

in Tetrahedron Letters (1999), 40(32), 5943-5944

The title species have been shown to rearrange under the influence of the electrophile PhSCl to give tetrasubstituted vinylaluminium compounds protonolysis of which led to the corresponding vinyl sulfides ... [more ▼]

The title species have been shown to rearrange under the influence of the electrophile PhSCl to give tetrasubstituted vinylaluminium compounds protonolysis of which led to the corresponding vinyl sulfides in a highly stereoselective manner. [less ▲]

Lyngbyapeptin A, a modified tetrapeptide from Lyngbya bouillonii (Cyanophyceae)

in Tetrahedron Letters (1999)

Lyngbyapeptin A 1, a novel tetrapeptide containing the rate 3-methoxy-2-butenoyl moiety was isolated from the cyanobacterium Lyngbya bouillonii, collected in Papua New Guinea. Its structure (without ... [more ▼]

Lyngbyapeptin A 1, a novel tetrapeptide containing the rate 3-methoxy-2-butenoyl moiety was isolated from the cyanobacterium Lyngbya bouillonii, collected in Papua New Guinea. Its structure (without stereochemistry) was established by mass spectral- and two-dimensional NMR studies. [less ▲]