<b>Organic Sulfur Compounds. VIII. Addition of Thiols to Conjugated Diolefins</b>

Oswald, Alexis A.; Griesbaum, Karl; Thaler, Warren A.; Hudson, Boyd E.

doi:10.1021/ja00879a020

Cited by 66 publications

(26 citation statements)

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“…The order of reactivity 1,2->> 1,4-cis > 1,4-trans units was first observed by Serniuk et al; [13] a similar trend of the addition rates was especially confirmed by 'model reactions' between thiols and simple olefins resembling the structural units of PBL-type rubbers (for instance, internal cis-and trans-or terminal olefines). [13][14][15] This interesting order of reactivity was also observed in later studies on similar model compounds [16][17][18][19][20][21] or with unsaturated polymers. [16][17][18][19][20][21][22][23][24][25][26][27][28] Another remarkable mechanism aspect was a noticeable anti-Markovnikov behaviour of the addition reaction.…”

Section: Introductionsupporting

confidence: 63%

“…[16][17][18][19][20][21][22][23][24][25][26][27][28] Another remarkable mechanism aspect was a noticeable anti-Markovnikov behaviour of the addition reaction. [6,7,14,15,29,30] During the 1980s, Priola et al [27,28] obtained functionalised PBLs with 2-mercaptoethanol, TGA, 3-mercaptopropanoic acid or (mercaptopropyl)trimethoxy silane (MPTS) by using photoinitiators under UV lighting. Gorski and coworkers [19,24,25] used 8-mercaptooctan-1-ol or MPTS [24,25] with the same polymeric substrates to obtain a PB that, under particular conditions, could undergo a sol-gel process by creating a cross-linked resin.…”

Section: Introductionmentioning

confidence: 99%

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Thiol‐Ene Radical Addition of L‐Cysteine Derivatives to Low Molecular Weight Polybutadiene

Lotti

Coiai

Ciardelli

et al. 2009

Macro Chemistry & Physics

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The functionalisation of a low molecular weight, liquid 1,2‐polybutadiene (PBL) was performed by the addition of either N‐acetyl‐L‐cysteine or its methyl ester through the thiol‐ene radical reaction. The functionalisation runs were carried out in 1,4‐dioxane solution and in the presence of a free radical initiator (2,2′‐azobisisobutyrronitrile, AIBN). The initial feed ratio polymer/cysteine derivative/initiator was varied, in order to highlight the occurrence of side reactions and to understand their possible influence on the process. The 1H NMR determination of the functionalisation degree brought out high addition degrees of thiols, regardless of the initial thiol/double bonds ratio. This caused a drastic change in the macroscopic properties of the PBL with improved solubility in hydrophilic solvents (for instance in alkaline aqueous solutions) and impressive increase of the glass transition temperature. The propagation of chiral properties from the functionalising agents to the modified polymers was evaluated by polarimetry and circular dichroism in solution.magnified image

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Section: Introductionsupporting

confidence: 63%

Section: Introductionmentioning

confidence: 99%

Thiol‐Ene Radical Addition of L‐Cysteine Derivatives to Low Molecular Weight Polybutadiene

Lotti

Coiai

Ciardelli

et al. 2009

Macro Chemistry & Physics

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“…The photoaddition is regiospecific (1 1) in its orientation in which the piperidino group always attaches itself to the 1-position of the symmetrical diene system while the nitroso group goes to either the 2-position or the 4-position. A free radical addition to a conjugated diene generally gives more 1,4-adducts than 1,2-adducts (12)(13)(14) trend is reversed if a metal ion is involved during the addition (15,16). However, there is no predictable pattern on the mode of addition in an ionic mechanism (10).…”

Section: Discussionmentioning

confidence: 99%

Photochemistry of nitroso compounds in solution. XV. Configuration and conformation of the enone oximes obtained from photoaddition of N-nitrosopiperidine to conjugated dienes

Chow¹,

Colón²,

Chang³

1970

Can. J. Chem.

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In the presence of an acid, N-nitrosopiperidine photolytically adds to conjugated dienes to give 1 :1 adducts in excellent yield. While the major products are the syn-and anti-isomers of piperidino a,Punsaturated oxime derived from 1,4-addition, similar types of oximes derived from 1,2-addition are also obtained. The ratio of syr2-and anti-oximes is determined by the relative configurational and the conformational stabilities of the two forms. The nuclear magnetic resonance (n.m.r.) chemical shifts and coupling constants provide useful information for the determination of the configuration and conformation of the oximes. A comparison of the n.m.r. data from a$-unsaturated oximes indicates that the a-proton generally resonates at a lower field than the a-proton in contrast to the chemical shifts of a$-unsaturated carbonyl compounds. The photoaddition of nitrosopiperidine to cycloheptatriene gave tropone oxime, probably through the elimination of piperidine from the 1 :1 adduct.

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“…The phenoxyl radical can be reduced nonenzymatically by thiols (reaction 4) producing additional thiyl free radicals (Rao et al 1990). Although a number of different reactions with the thiyl free radical are possible, it is well known that thiyl free radicals will react nonenzymatically with alkenes (Oswald et al 1962), as described for 4-CA in reaction 5. The thiyl radical would attack the less hindered carbon atom of the alkene, forming a carbon-centered radical around the other carbon (reaction 5).…”

Section: Discussionmentioning

confidence: 99%

Peroxidase-mediated conjugation of glutathione to unsaturated phenylpropanoids. Evidence against glutathione S-transferase involvement

Dean¹,

Devarenne²

1997

Physiol Plant

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Dean, J. V. and Devarenne, T. P. 1997. Peroxidase-mediated conjugation of glutathione 10 unsaturated phenylpropanoids. Evidence against glutathione S-transferase involvement. -Physiol. Planl. 99: 271-278.A number of plant species are thought to possess a glutathione S-transferase enzyme (GST: EC 2.5.1.18) that will conjugate glutathione (GSH) to (ran.s-cinnamic acid (C.A) and para-coumaric acid (4-CA). However, we present evidence thai this activityis mediated by peroxidase enzymes and not GSTs. The N-lerminal amino acid sequence of the GSH-conjugating enzyme purified from etiolated com shoots exhihited a strong degree of homology to cylosolic ascorhate peroxidase enzymes (APX: EC 1.11.1.11) from a numher of planl species. The GSH-conjugating and APX activities of com could not he separated during chromatography on hydrophobic-interaction. anion-exchange, and gel filtration columns. Spectral analysis of the enzyme revealed that the protein had a Soret band at 405 nm. When the enzyme was reduced with dithionite, the peak was shifted to 423 nm with an additional peak at 554 nm. The spectmm of the dithionite-reduced enzyme in the presence of 0.1 mM KCN exhibited peaks at 430, 534 and 563 nm. These spectra are consistent with the presence of a heme moiety. The GSH-conjugating and APX activities of the enzyme were both inhibited hy KCN, NaN,, /)-chloromercuribenzoaie (pCMB), and iodoacetate. The APX specific activity of the enz\ me was 1.5-fold greater than the GSH-conjugating specific activity with 4-CA. In addition to the com enzyme, a pea recombinanl APX (rAPX) and horseradish peroxidase (HRP: EC 1.11.1.7) were also able to conjugate GSH to CA and 4-CA. The peroxidase enzymes may generate thiyi free radicals of GSH Ihat react with the alkyl douhle bond of CA and 4-CA resulting in the formation of a GSH conjugate.

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Organic Sulfur Compounds. VIII. Addition of Thiols to Conjugated Diolefins

Cited by 66 publications

References 0 publications

Thiol‐Ene Radical Addition of L‐Cysteine Derivatives to Low Molecular Weight Polybutadiene

Thiol‐Ene Radical Addition of L‐Cysteine Derivatives to Low Molecular Weight Polybutadiene

Photochemistry of nitroso compounds in solution. XV. Configuration and conformation of the enone oximes obtained from photoaddition of N-nitrosopiperidine to conjugated dienes

Peroxidase-mediated conjugation of glutathione to unsaturated phenylpropanoids. Evidence against glutathione S-transferase involvement

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