Unsaturated thioethers

In another method for the coupling of two different allylic groups, a carbanion derived from a P,y-unsaturated thioether couples with an allylic halide. The... 

Treatment of a-(benzotriazol-l-yl)alkyl thioethers 831 with ZnBr2 weakens the bond with benzotriazole, and the obtained complex 832 may partially dissociate to thionium cation 835 that can be trapped by even mild nucleophiles. Thus, trimethylsilyl cyanide added to the reaction mixture causes substitution of the benzotriazole moiety by the CN group to give a-(phenylthio)carbonitrile 834. In a similar manner, treatment with allylsilane leads to y,S-unsaturated thioether 833. Addition of species 835 to the double bond of a trimethylsilyl ot-arylvinyl ether followed by hydrolysis of the silyloxy group furnishes (i-(phenylthio)alkyl aryl ketones 836 (Scheme 132) <1996TL6631>. 

Unsaturated thioethers represent a valuable alternative to organic halides as electrophilic partners in nickel-catalyzed cross-coupHng reactions with C(sp )-organozincs [284]. As in the case of aryl- and heteroarylzinc hahdes, high-yielding cross-coupling between an array of thiomethylated N-heterocycles and benzyl- or... 

However, more recent experiments of V. Macho [135,136] and L. Marko et al, [137-144, 829, 913, 953-955] showed that these assumptions have to be corrected. They proved that some sulfur compounds (e.g. saturated thioethers and thiophene) are practically of no harm to the hydroformylation, but that other compounds (e. g. COS, HgS, unsaturated thioethers, mercaptans, mercaptals, disulfides, CSg and elementary sulfur) inhibit the 0X0 reaction by forming sulfur-containing cobalt carbonyls which are inactive as oxo catalysts and less soluble than carbonyls. In the course... 

The urine of the red fox contains a scent marker that is an unsaturated thioether. Classify the degree of substitution of the double bond of the scent marker. 

On the other hand, the enantioselective 1,4-addition of carbanions such as enolates to linear enones is an interesting challenge, since relatively few efficient methods exist for these transformations. The Michael reaction of p-dicarbonyl compounds with a,p-unsaturated ketones can be catalysed by a number of transition-metal compounds. The asymmetric version of this reaction has been performed using chiral diol, diamine, and diphosphine ligands. In the past few years, bidentate and polydentate thioethers have begun to be considered as chiral ligands for this reaction. As an example, Christoffers et al. have developed the synthesis of several S/O-bidentate and S/O/S-tridentate thioether... 

The base-catalysed addition of thiols to Jt-electron-deficient alkenes is an important aspect of synthetic organic chemistry. Particular use of Triton-B, in place of inorganic bases, has been made in the reaction of both aryl and alkyl thiols with 1-acyloxy-l-cyanoethene, which behaves as a formyl anion equivalent in the reaction [1], Tetra-n-butylammonium and benzyltriethylammonium fluoride also catalyse the Michael-type addition of thiols to a,P-unsaturated carbonyl compounds [2], The reaction is usually conducted under homogeneous conditions in telrahydrofuran, 1,2-dimethoxyethane, acetone, or acetonitrile, to produce the thioethers in almost quantitative yields (Table 4.22). Use has also been made of polymer-supported qua-... 

Bromination of the enol ether product with two equivalents of bromine followed by dehydrobromination afforded the Z-bromoenol ether (Eq. 79) which could be converted to the zinc reagent and cross-coupled with aryl halides [242]. Dehydrobromination in the presence of thiophenol followed by bromination/dehydrobromination affords an enol thioether [243]. Oxidation to the sulfone, followed by exposure to triethylamine in ether, resulted in dehydrobromination to the unstable alkynyl sulfone which could be trapped with dienes in situ. Alternatively, dehydrobromination of the sulfide in the presence of allylic alcohols results in the formation of allyl vinyl ethers which undergo Claisen rearrangements [244]. Further oxidation followed by sulfoxide elimination results in highly unsaturated trifluoromethyl ketonic products (Eq. 80). 

Phenylthiotrimethylsilane adds to propenoyl trimethylsilane under the influence of Lewis acid to give l,3-bis(phenylthio)-l-trimethylsilylprop-l-ene (18). This enol thioether may be deprotonated with f-butyl lithium and alkylated with any of a large range of electrophiles. Subsequent hydrolysis-elimination with mercuric chloride in aqueous acetonitrile provides -substituted a,/J-unsaturated acyl silanes (vide supra, Section III.D.3)132. It should be noted that, in this transformation, the /1-substituent has... 

Pd),99 and quasi-symmetrical MCipSo and MCortho contacts (2.019(3)/2.081 (3) A for Ni, and 2.198(4)/2.325(4) A for Pd). The preference for ip -BCC vs. ri1-B bonding of the PSB ligand in these complexes was attributed to the coordinatively unsaturated nature of the metal fragments (formal 14e counts when only the coordination of the phosphine and thioether moieties are taken into account). 

The thioether ligand L36 and CuCN in their separate solid-state forms feature emissions at 549 and 400 nm, respectively. The most intense emission of polymer 36 is observed red shifted at 614 nm, which is ascribed to the different packing of the L36 linkers as well as the electronic interaction of across the L36 unsaturated molecules and the Cu—CN—Cu chains. 

T.R. Juneja et al., Effect of various alkyl and unsaturated substituents on the mutagenicity of some nitrophenyl thioethers. Mutat. Res. 495, 97-102 (2001)... 

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