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Electron-rich thiophenes were trifluoroacetylated by trifluoroacetic anhydride with different nitrogen bases in dichloromethane at room temperature in good yields. Trifluoroacetylation without a base gave significantly lower yields. Trifluoroacetylation of electron-rich thiophenes

(Z)-5-(Bromomethylene)thiophen-2(5H)-one reacts in a Michael-type addition across the methylene side chain with nucleophiles followed by elimination of bromide. The reaction was done at room temperature and the yields were good. The aromatic sulfur substitution products showed potent activity as biofilm inhibitors.

Electron-rich thiophenes were trifluoroacetylated by trifluoroacetic anhydride with different nitrogen bases in dichloromethane at room temperature in good yields. Trifluoroacetylation without a base gave significantly lower yields.

Oxo-substituted α-chloro ethers have been prepared by cleavage of the corresponding O,Sacetals with sulfuryl dichloride. Some of these α-chloro ethers give hydroxysubstituted oxygen heterocycles when reacted with samarium diiodide.

(Z)-5-(Bromomethylene)thiophen-2(5H)-one reacts in a Michael-type addition across the methylene side chain with nucleophiles followed by elimination of bromide. The reaction was done at room temperature and the yields were good. The aromatic sulfur substitution products showed potent activity as biofilm inhibitors.

The disulfide bridge in cystine has formally been replaced by substitution of two α-alanines at the β-carbon into the 2,3-positions in 1,3-butadiene. The key reactions are stereoselective alkylation of lithiated (2S)-2,5-dihydro-3,6-dimethoxy-2-isopropylpyrazine with 2,3-dibromopropene. The alkene-alkene bond formation was effected by Pd-catalysis either with the 2′-bromoallyl products from the alkylation as substrate or with the corresponding amino acid appropriately protected.

Carbosubstitution in halogenoazines with alkyl groups is readily effected under the influence of Pd-catalysis with alanes as the donor of the alkyl group.

A method for α-alkylation of saturated 5-, 6-, 7- and 8-membered aza-heterocycles is described. The auxiliary is an o -iodobenzyl group attached at the nitrogen. A radical introduced in the o -position is transferred to the amine α-position which subsequently leads to an addition reaction with pentan-3-one.

A method for α-alkylation of saturated 5-, 6-, 7- and 8-membered aza-heterocycles is described. The auxiliary is an o -iodobenzyl group attached at the nitrogen. A radical introduced in the o -position is transferred to the amine α-position which subsequently leads to an addition reaction with pentan-3-one.

Pyrimidines have been stannylated in the activated 4-position by thermal decar☐ylation of the corresponding car☐ylic organotin esters. The decar☐ylation can be catalyzed by bis(acetonitrile)palladium(II) dichloride. 4-Iodopyrimidines are 4-stannylated either by substitution reactions with tri-n-butyltin-copper or by coupling reaction with hexamethyl- or hexa-n-butyl-ditin and Pd(II) catalysis. The stannylated pyrimidines form new carbon-carbon bonds by Pd(II)-catalyzed cross-couplings, tert-Butyldimethylsilyl-, dimethylthexylsilyl- and tert-butyldiphenylsilyl-oxymethyl (tri-n-butyl)tin have been synthesized and used in Pd(II)-catalyzed cross-coupling reactions with 4-chloropyrimidines. The silyi groups were not cleaved off during exposure to fluoride ions in aqueous media but were readily removed by fluoride ions in THF to yield the 4-hydroxymethylpyrimidine.

An epithermal energy neutron irradiation facility has been used to perform instrumental activation analysis for iodine, silicon, nickel, zirconium, uranium and thorium. The facility, which is adjacent to the fuel of the University of Virginia 2.0 MW pool reactor, consists of a dry sample region surrounded by a fixed cadmium shield. A boron nitride capsule can be used to hold the sample in the cadmium facility to further enhance the reduction of thermal neutron activation. The neutron fluence rate is 2.2×1016 n·m−2·s−1 for fission spectrum energy neutrons (measured with Ni(n,p)Co) and 8.2·1015 n·m−2·s−1 for resonance energy neutrons (measured with gold).

Synthese en particulier de bromo-2, chloro-2 acetophenones, bromo-1, chloro-1 heptanone-2, chloro-5, bromo-5 oxo-4 valerate de methyle et [chloro(bromo) methyl cyclohexyl) cetones