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The preparation of diaryl and alkyl aryl sulfides via acid-mediated coupling of thiols and thioethers with diaryliodonium salts is reported. The scope, limitations, and mechanism of the transformation are discussed.

Depending on the solvent, MeOH or water, the microwave-assisted rearrangement of propargyl vinyl ethers affords alkenes bearing a malonate unit, or an ester/free acid group at the allylic position.

In the course of our investigations, we have discovered that the anodic dissolution of Pd in 1Mh 2 SO 4 solution is actually catalyzed by the presence of a single layer of chemisorbed iodine atoms even if the sulfuric acid solution does not contain halide anions. The results which demonstrate the adsorbate-catalyzed corrosion in halide-free acid solutions are the subject of this communication

(2R,3S)-3-(4-Methoxyphenyl)glycidic esters were efficiently synthesized by the optical resolution of the racemic acid and esterification of the optically active acid thus obtained, in the form of its alkali metal salt.

Symmetrical dinucleoside 5'-pyrophosphates have been synthesized from the corresponding nucleoside 5'-phosphate free acid in high yield. The one-pot procedure is carried out in DMF or DMSO using triphenylphosphine and 2,2'-dipyridyldisulfide as the coupling agents, and 1-methylimidazole as the catalyst.

The crystal and molecular structures of 2-amino-2-deoxy-α/ β-D-glucopyranose 3-sulfate (1) and 2-amino-2-deoxy-β-D-glucopyranose 6-sulfate (2) have been determined by direct methods. The sugar rings have the expected 4C1 conformation and the geometries of the sulfate groups are comparable with those found in previous investigations except for a significant shortening of the CO bond and closing of the COS bond angle in 2.

The title compounds were synthesized by cyclizing 3-dimethylaminomethylene-4-chromanone with creatine to give the acid 2 that was successively converted into the corresponding amides 3a-f via diphenylphosphorylazide and the relevant amines. The free acid 2 and some of 3a-f showed antiinflammatory, hypotensive and antiarrhythmic properties.

An acylative C(3)–C(4)-bond cleavage of ethyl 4,5-disubstituted 2-(trimethylsilylmethyl)penta-2,4-dienoate occurred to give an ethyl 2-(2-oxoalkyl)acrylate by treatment with trifluoromethanesulfonic acid in nitriles. A self-cyclization also occurred to give a 5,5-disubstituted 3-methylenetetrahydrofuran-2-one when the reactions were carried out in bulky nitriles. Only self-cyclization proceeded when the corresponding 4,5-disubstituted 2-(trimethylsilylmethyl)penta-2,4-dienoic acid was treated in acetonitrile. The reaction mechanism is described.

The CuBr-promoted coupling reaction of [(diethoxyphosphinyl)difluoromethyl]zinc bromide 6 with aryl iodides in either DMF or DMA was examined to give a series of aryl(difluoromethyl)phosphonates. The coupling reaction was applicable to the selective synthesis of α,α-difluoro-4- iodobenzylphosphonale 11e, a useful intermediate for the preparation of F2Pmp. 1-[(Diethylphosphono)difluoromethyl] naphthalene 15 and the regioisomer 16 were obtained in high yields from 1- and 2-iodonaphthalene, respectively. The phosphonate 16 was transformed to the free acid 4a, a low molecular-mass inhibitor of protein phosphatases.

Reaction of diethylenetriamino pentaacetic acid (dtpa) dianhydride with aromatic/heterocyclic sulfonamides possessing a free amino/imino/hydrazino/hydroxy group afforded bis-sulfonamides containing metal-complexing, polyamino-polycarboxylic acid moieties in their molecule. The corresponding mono-sulfonamide derivatives of dtpa were also obtained by an alternative method, from the free acid. Zn(II) complexes of these new sulfonamides were then prepared. Many of these derivatives showed nanomolar affinity towards isozymes I, II and IV of carbonic anhydrase (CA). Some of the best inhibitors were applied as 2% water solutions/suspensions into the eye of normotensive or glaucomatous albino rabbits, when strong and long-lasting intraocular pressure (IOP) lowering was observed.

A total synthesis of the biaryl antibiotic biphenomycin B is reported which makes use of three independent building blocks (key steps were a clean Suzuki-Miyaura coupling of a free acid iodide, a novel 4-hydroxyornithine synthesis, and a high-yielding macrolactamization); a practical deprotection protocol allowed isolation of the target compound with excellent recovery and purity.

The preparation and structural characterization of a novel molecular solid Bronsted acid based on the Dawson-type sandwich polyoxometalate (POM) are described. The free-acid form of POM, i.e., 8H+-...

Bovine d -galactosyltransferase was found to transfer d -galactose from UDP-galactose to 6-O-substituted 2-acetamido-2-deoxy-β- d -glucopyranosides. The resulting 6-O-substituted N-acetyllactosamines were readily synthesized in milligram amounts and conveniently isolated on a reverse-phase support when prepared as the 8-methoxycarbonyloctyl glycosides. The 6-O-substitution tolerated by the enzyme include an α- l -fucopyranosyl group and the methyl ester of α-linked N-acetylneuraminic acid, but not the free acid itself. The product trisaccharides were characterized by 1H-n.m.r. spectroscopy and fast-atom-bombardment mass spectrometry.

p- Nitrobenzyl (2R,3R)-2-(benzothiazol-2′-yldithio)-α-isopropylidene-4- oxo-3-phenoxyacetyl-aminoazetidine-1-acetate (7), readily prepared from penicillin V, can be converted into the corresponding 2-allylthio compound (2) by addition of allyl bromide and sodium borohydride at a low temperature. This compound (2) on treatment with ozone, followed by cyclization with trimethyl phosphite, produces a 3H-ceph-3-em ester (4). The ester can be easily de-esterified to the free acid (1b).

Benzyl 5,6-dihydroxyindole-2-carboxylate 3 and the free acid 4 were synthesized by oxidative cyclization of dopa benzyl ester with ceric ammonium nitrate and subsequent removal of the benzyl group by hydrogenation.