Presence Of Vinyl Ether Research Articles

ChemInform Abstract: Regioselective (3 + 2)Annulations with Rhodium(II)-Stabilized Vinylcarbenoids.

Abstract Construction of two series of cyclopentenes with predictable regiochemistry was achieved by means of rhodium(lI)-catalyzed decomposition of vinyldiazomethanes in the presence of vinyl ethers.

Palladium-Catalyzed Dimerization of Vinyl Ethers to Acetals

(Alpha-diimine)PdCl(+) species catalytically dimerize alkyl and silyl vinyl ethers to beta,gamma-unsaturated CH(2)=CHCH(2)CH(OR)(2) acetals, and they cyclize divinyl ethers to analogous cyclic acetals. A plausible mechanism comprises in situ generation of an active PdOR alkoxide species, double vinyl ether insertion to generate Pd{CH(2)CH(OR)CH(2)CH(OR)(2)} species, and beta-OR elimination to generate the acetal product. In the presence of vinyl ethers, (alpha-diimine)PdCl(+) species can be used to initiate ethylene polymerization.

Photoinduced Three-Component Reaction: A Convenient Access to 3-Arylacetals or 3-Arylketals

A mild and versatile method for the photoinduced three-component synthesis of 3-arylacetals and ketals is presented. Desired targets are smoothly obtained by irradiating aromatic halides or esters in alcohols, in the presence of vinyl ethers.

A new efficient tetraphosphine/palladium catalyst for the Heck reaction of aryl halides with styrene or vinylether derivatives

cis, cis, cis-1,2,3,4-Tetrakis(diphenylphosphinomethyl)cyclopentane/[PdCl(C 3H 5)] 2 system efficiently catalyses the Heck reaction of aryl halides with styrene and vinylether derivatives. High turnover numbers can be obtained for the reaction of several aryl halides with styrene and styrene derivatives. Lower turnover numbers have been observed in the presence of vinylethers.

Interaction of epoxy and vinyl ethers during photoinitiated cationic polymerization

A kinetic study of the independent and simultaneous photoinitiated cationic polymerization of a number of epoxide and vinyl (enol) ether monomer pairs was conducted. The results show that, although no appreciable copolymerization takes place, these monomers undergo complex interactions with one another. These interactions are highly dependent on the epoxide monomer employed. In all cases, the rate of epoxide ring-opening polymerization is accelerated, whereas that of the vinyl ether is depressed. When highly reactive cycloaliphatic epoxides are subjected to photoinitiated cationic polymerization in the presence of vinyl ethers, the two polymerizations proceed in a sequential fashion, with the vinyl ether polymerization taking place after the epoxide polymerization is essentially complete. A mechanism involving an equilibration between alkoxy-carbenium and oxonium ions has been proposed to explain the results. In addition, the free-radical-induced decomposition of the diaryliodonium salt photoinitiator also takes place, leading to a decrease in the induction period. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 4007–4018, 1999

Solvent effects on photocycloadditions of dibenzoylmethanatoboron difluoride with enol ethers

The photolysis of dibenzoylmethanatoboron difluoride (DBMBF 2) in the presence of vinyl ethers in acetonitrile gave dimers of the latter from acid catalysis or electron transfer sensitization, but, it contrast, gave cycloaddition products in an efficient reaction in less polar solvents such as tetrahydrofuran (THF) and benzene.

Synthesis of Ether Analogues of (±)-Acetomycin

Short syntheses of (±)-2a-c, ether analogues of acetomycin (1a) are described. The approach is based on a novel entry to furanones by rearrangement of tert-butyl 1-vinylcyclopropane-1-carboxylates. The cyclopropanes are stereoselectively formed by the rhodium(II) catalyzed decomposition of vinyldiazomethanes in the presence of vinyl ethers

Regioselective [3 + 2] annulations with rhodium(ii)-stabilized vinylcarbenoids

Construction of two series of cyclopentenes with predictable regiochemistry was achieved by means of rhodium(lI)-catalyzed decomposition of vinyldiazomethanes in the presence of vinyl ethers.

THE PHOTOCYCLOADDITION OF 9-CYANOPHENANTHRENE AND 9-CYANOANTHRACENE WITH VINYL ETHERS AND FURAN

Abstract The photocycloaddition of 9-cyanophenanthrene with a vinyl ether affords a (2 + 2) cycloadduct, 1-cyano-8-alkoxy-2,3;4,5-dibenzobicyclo[4.2.0] octa-2,4-diene (I), but no 1:1-adduct can be obtained with furan, whereas irradiation of 9-cyanoanthracene in the presence of furan gives a (4 + 4) cycloadduct, 1-cyano-7,8;9,10-dibenzo-11-oxatricyclo[4.2.2.12,5] undeca-3,7,9-triene (III), but no 1:1-adduct is given by the irradiation in the presence of vinyl ethers.