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Sulfur nucleophile

Displacement Reactions with Carbon, O.xygen. and Sulfur Nucleophiles... [Pg.244]

Reaction with Sulfur Nucleophiles, Because sulfai is highly nucleophilic, reactions of aziridines with sulfur nucleophiles generally proceed rapidly (111) and with good yields. The reaction of hydrogen sulfide [7783-06S-J with ethyleneimine yields cysteamine [60-23-1] (2-mercaptoethylamine) or bis(2-aminoethyl)sulfide [871-76-1] (2,112) depending on the molar ratio of the reactants. The use of NaHS for the synthesis of cysteamine has also been described (113). [Pg.5]

Reaction with Selenium Nucleophiles. The reactions of selenium nucleophiles are similar to those of the sulfur nucleophiles selenophosphates can be aminoaLkylated (135). A dihydroselenazine has been obtained by reaction of diethyl ketone, elementary selenium, and ethyleneimine (136). [Pg.5]

This addition is general, extending to nitrogen, oxygen, carbon, and sulfur nucleophiles. This reactivity of the quinone methide (23) is appHed in the synthesis of a variety of stabili2ers for plastics. The presence of two tert-huty groups ortho to the hydroxyl group, is the stmctural feature responsible for the antioxidant activity that these molecules exhibit (see Antioxidants). [Pg.61]

Nitrogen nucleophiles used to diplace the 3 -acetoxy group include substituted pyridines, quinolines, pyrimidines, triazoles, pyrazoles, azide, and even aniline and methylaniline if the pH is controlled at 7.5. Sulfur nucleophiles include aLkylthiols, thiosulfate, thio and dithio acids, carbamates and carbonates, thioureas, thioamides, and most importandy, from a biological viewpoint, heterocycHc thiols. The yields of the displacement reactions vary widely. Two general approaches for improving 3 -acetoxy displacement have been reported. One approach involves initial, or in situ conversion of the acetoxy moiety to a more facile leaving group. The other approach utilizes Lewis or Brmnsted acid activation (87). [Pg.32]

In forcing conditions with excess of reagents the 5,8-bis derivative was obtained in the above cases, with hydrazine and with sulfur nucleophiles. Other authors have also observed selective reactions in the pyrido[2,3-[Pg.242]

Many other examples are known of non-selective reactions of halo groups in pyridopyridazines with amines, alkoxides, sulfur nucleophiles such as hydrosulfide and thiolate ions, or thiourea, hydrazine(s), cyanide ion and dimethyl sulfoxide, or on catalytic reduction. [Pg.242]

The action of sulfur nucleophiles like sodium bisulfite and thiophenols causes even pteridines that are unreactive towards water or alcohols to undergo covalent addition reactions. Thus, pteridin-7-one smoothly adds the named S-nucleophiles in a 1 1 ratio to C-6 (65JCS6930). Similarly, pteridin-4-one (73) yields adducts (74) in a 2 1 ratio at C-6 and C-7 exclusively (equation 14), as do 4-aminopteridine and lumazine with sodium bisulfite. Xanthopterin forms a 7,8-adduct and 7,8-dihydropterin can easily be converted to sodium 5,6,7,8-tetrahydropterin-6-sulfonate (66JCS(C)285), which leads to pterin-6-sulfonic acid on oxidation (59HCA1854). [Pg.287]

Data on reactions of sulfur nucleophiles with azoles are sparse. Oxazoles are transformed in low yield into the corresponding thiazoles over alumina with HiS at 350 °C (74AHC( 17)99). Sulfur nucleophiles such as SH or RS add to 1,3-dithiolylium salts at the 2-position... [Pg.66]

Very little is known about nucleophilic attack on an unsubstituted carbon atom of pyrazoles and their aromatic derivatives (pyrazolones, pyrazolium ions). The SwAr reaction of halogenopyrazoles will be discussed in Section 4.04.2.3.7. Sulfur nucleophiles do not attack the ring carbon atoms of pyrazolium salts but instead the substituent carbon linked to nitrogen with concomitant dequaternization (Section 4.04.2.3.lO(ii)). The ring opening of pyrazolium salts by hydroxide ion occurs only if carbon C-3 is unsubstituted the exact mechanism is unknown and perhaps involves an initial attack of OH on C-3. [Pg.243]

Thiirane 1-oxide undergoes acid-catalyzed ring opening by ethanethiol to give ethyl 2-ethylthioethyl disulfide. Treatment of thiirane 1,1-dioxide with thiolate anions, sodium sulfide or thiourea gives /3-mercaptosulfinic acid derivatives (75S55). Thiiranium ions are attacked at carbon by most sulfur nucleophiles (79ACR282), but see Section 5.06.3.4.3 for exceptions. [Pg.161]

When 6-diazopenicillanates are irradiated in the presence of sulfur nucleophiles, predominantly 6/3-substitution products are obtained (77JOC2224). When BFs-EtiO is used to catalyze the reaction with nucleophiles, however, the products are primarily the 6a-isomers (78TL995). The use of rhodium or copper catalysis led primarily to ring-opened thiazepine products, presumably by way of the intermediate (56 Scheme 39) (80CC798). [Pg.320]

The biological activity of calicheamicin 4 (simplified structure) is based on the ability to damage DNA. At the reaction site, initially the distance between the triple bonds is diminished by an addition reaction of a sulfur nucleophile to the enone carbon-carbon double bond, whereupon the Bergman cyclization takes place leading to the benzenoid diradical 5, which is capable of cleaving double-stranded DNA." ... [Pg.40]

Thiols are usually prepared from alkyl halides by Snj2 displacement with a sulfur nucleophile such as hydrosulfide anion, SH. [Pg.667]

With Sulfur Nucleophiles N-Carboxy-protected aziridine-2-carboxylates react with thiols to give P-mercapto-ot-amino acid derivatives. The reaction is usually catalyzed by BF3 and the yields range from fair to excellent [15, 16, 108-111]. With N-unprotected 3-substituted aziridine-2-carboxylates, the ring-opening with thiols usually takes place with anti stereoselectivity, especially in the case of the C-3 aliphatic substituted substrates. In cases in which C-3 is aromatic, however, the stereoselectivity has been found to be a function of the substitution pattern on the aromatic ring 3-p-methoxy ph eri yl-su bs li In led aziridines 143a (Scheme 3.51) and... [Pg.93]


See other pages where Sulfur nucleophile is mentioned: [Pg.384]    [Pg.242]    [Pg.140]    [Pg.24]    [Pg.153]    [Pg.160]    [Pg.616]    [Pg.618]    [Pg.698]    [Pg.751]    [Pg.754]    [Pg.755]    [Pg.755]    [Pg.756]    [Pg.887]    [Pg.924]    [Pg.164]    [Pg.209]    [Pg.367]    [Pg.391]    [Pg.101]    [Pg.189]    [Pg.189]    [Pg.189]    [Pg.197]    [Pg.223]    [Pg.242]    [Pg.37]    [Pg.193]    [Pg.489]    [Pg.439]    [Pg.495]   
See also in sourсe #XX -- [ Pg.117 ]




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Addition of Carbon, Oxygen, Nitrogen, and Sulfur Nucleophiles

Addition of Sulfur Nucleophiles

And sulfur nucleophiles

Carboxylic acid derivatives with sulfur nucleophiles

Cascade reactions sulfur nucleophiles

Conjugate addition of sulfur nucleophiles

Conjugate sulfur nucleophiles

Displacement reactions, nucleophilic on sulfur atoms

Glutathione-Mediated and Other Reactions Involving Nucleophilic Sulfur

Halides, aryl reaction with sulfur nucleophiles

Intermolecular reactions sulfur nucleophiles

Nucleophiles sulfur compounds

Nucleophiles sulfur-based

Nucleophiles sulfur-stabilized

Nucleophiles, sulfur

Nucleophiles, sulfur

Nucleophilic Attack at Ring Sulfur

Nucleophilic Attack on Sulfur

Nucleophilic Substitution at the Nitrogen, Phosphorus, and Sulfur Centers

Nucleophilic addition reactions with sulfur nucleophiles

Nucleophilic addition sulfur nucleophiles

Nucleophilic attack at sulfur

Nucleophilic reactions conjugate additions, sulfur/selenium

Nucleophilic reactivity of sulfur compounds

Nucleophilic substitution sulfur/selenium nucleophiles

Nucleophilic sulfur

Nucleophilic sulfur

Oxygen and Sulfur as Nucleophiles

Oxygen and sulfur as nucleophiles ethers, esters, thioethers, epoxides

Penicillin sulfoxide sulfur nucleophiles

Phosphorus and Sulfur Nucleophiles

Polyglymes sulfur nucleophiles

Reaction with Oxygen and Sulfur Nucleophiles

Reactions of Sulfur-Based Nucleophiles with Halogenated Aliphatics

Reactions with sulfur nucleophiles

Rearrangement sulfur nucleophiles

Ring with sulfur-based nucleophiles

Sulfonyl sulfur, nucleophilic

Sulfonyl sulfur, nucleophilic substitution

Sulfur Ylides and Related Nucleophiles

Sulfur Ylides and Related Species as Nucleophiles

Sulfur as nucleophile

Sulfur dioxide nucleophiles

Sulfur nucleophile equilibrium constant

Sulfur nucleophile, definition

Sulfur nucleophiles Group

Sulfur nucleophiles addition

Sulfur nucleophiles allylic compounds

Sulfur nucleophiles aromatic nucleophilic substitution

Sulfur nucleophiles asymmetric allylation

Sulfur nucleophiles containing

Sulfur nucleophiles formation

Sulfur nucleophiles in natural waters

Sulfur nucleophiles regioselectivity

Sulfur nucleophiles stereochemistry

Sulfur nucleophiles substitution reactions

Sulfur nucleophiles, addition with

Sulfur nucleophiles, reaction

Sulfur nucleophiles, reaction with arene oxides

Sulfur nucleophilic substitution

Sulfur, nucleophiles substituted cyclopropanes

Sulfur, nucleophiles ylides

Sulfur, nucleophiles ylids

Sulfur, selenium and phosphorus nucleophiles

Sulfur-based nucleophile

Sulfur-based soft nucleophiles

Sulfur-centered Nucleophiles

Sulfur-stabilized nucleophile

Sulfuric acid Sulfur nucleophiles

Sulfuric acid derivatives, nucleophilic substitution

The Addition of Sulfur Nucleophiles

The Synthesis of Chiral Sulfoxides through Nucleophilic Displacement at Sulfur

Transformations with Sulfur-Containing Nucleophiles

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