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Mercaptan adducts

The 6-deoxy-6-methylenetetracyclines and their corresponding mercaptan adducts possess typical characteristics tetracycline activity and illustrate further the level of modification feasible at C-6 with the possible retention of biologic activity. [Pg.776]

Both antimony tribromide and antimony ttiiodide are prepared by reaction of the elements. Their chemistry is similar to that of SbCl in that they readily hydroly2e, form complex haUde ions, and form a wide variety of adducts with ethers, aldehydes, mercaptans, etc. They are soluble in carbon disulfide, acetone, and chloroform. There has been considerable interest in the compounds antimony bromide sulfide [14794-85-5] antimony iodide sulfide [13868-38-1] ISSb, and antimony iodide selenide [15513-79-8] with respect to their soHd-state properties, ferroelectricity, pyroelectricity, photoconduction, and dielectric polarization. [Pg.204]

The latter compounds are of biological importance—cysteine, glutathione, and proteins are examples—and a novel antihypertensive drug, Captopril (Figure 9), also contains this functionality (59). Mercaptans can be prepared by the solvolysis of the thiolacetic acid adducts to olefins. [Pg.107]

Further routes of cyclizations have been studied in parallel in the case of cis- and rra/J5-2-hydroxymethyl-l-cyclohexylamine (106) (880PP73). The preparation of thiourea or urea adducts 107 and 108 with phenyl isothiocyanate or phenyl isocyanate proceeds smoothly. The reaction of 107 with methyl iodide and subsequent alkali treatment, by elimination of methyl mercaptan, resulted in the iminooxazine 109 in high yields. The ring closures of both cis and trans thiourea adducts to 1,3-oxazines proceed with retention. Cyclodesulfuration of the adduct 107 by mercury(II) oxide or N,N -dicyclohexylcarbodiimide resulted in the iminooxazine 109, but the yield was low and the purification of the product was cumbersome. The ring closure of 108 with thionyl chloride led to the iminooxazine 109 in only moderate yield. [Pg.366]

Ethyl mercaptan reacts with DMAD to give a 1 1 adduct through a trans mode of addition. WeibulP has reported that a mixture of both fumarate and maleate is formed from cyclohexyl mercaptan with propiolic acid. A similar observation has been made in the reaction of cyclohexyl mercaptan with acetylenedicarboxylic acid. ... [Pg.341]

Mercaptoacetone reacts with methyl propiolate to give a 1 1 adduct, which then cyclizes to a substituted thiophene. Similar addition reactions of mercaptans with acetylenic acids have also been reported by Owen and Sultanbawa. ... [Pg.342]

Organosulfur compounds such as alkene- and arine-thiols apparently stabilize nickel-sulfur bonds as indicated by the complexes which were reported to have mercaptans as unique ligands. The tetrahedral tetrakis adduct with benzenethiolate, (Ph4P)2[Ni(SPh)4] (267 /weB =... [Pg.167]

Fluorinated alkylisocyanates and isothiocyanates add alcohols, mercaptans, and amines to yield stable 1 1 adducts [76]. When the reaction is performed with carboxylic acids, the anhydrides first formed decompose to give A -fluoroalky-lated amides [77]... [Pg.844]

Base-catalyzed condensation of 2-(acetyl)thioindoxyl with aromatic aldehydes affords compounds with the general formula 330, which give the adducts 331 with aryl mercaptans in the presence of piperidine.582... [Pg.355]

The 2,3-double bond in benzo[6]thiophene-1,1-dioxides undergoes addition reactions with nucleophiles in a manner comparable to that of other a,/9-unsaturated sulfones no aromatic properties are detectable in this way for the thiophene ring.718-723 For example, thiophenol and p-thiocresol give the adducts (340 R = H or Me) in the presence of base.723 However, if the aryl mercaptan and the sulfone are heated together, a radical reaction occurs to give the corresponding 2-substituted compound.723 In contrast to the behavior of aryl mercap-... [Pg.359]

A further example of the use of copolymers of acrylonitrile and Cinchona alkaloids in asymmetric synthesis has been reported 127 thus these polymers catalyse the addition of benzyl mercaptan to w-nitrostyrene to give consistently an excess of the (+)-enantiomer of the adduct. [Pg.197]

While there were proposals in the literature claiming that FAD-requiring oxidations which are believed to take place via carbanion intermediates also proceed by covalent adducts with FAD, a careful examination of the evidence led Bruice to conclude that this need not be the case152. On the other hand, the covalent interaction with mercaptans is generally accepted. [Pg.1292]

Typically, electron transfer is preceded by the formation of an encounter complex. In the case of dissolution of solid, higher valence oxides, usually by organic reductants, this is usually a surface complex (see Figure 13.10). Here we briefly illustrate that the reduction of Cr(VI) by alcohols, a-hydroxycar-boxy lates, a-carbonyl carboxylates, and mercaptans occurs through formation of a Cr(VI) reductant adduct, A mechanism proposed by Stone (1994) for... [Pg.719]

In addition to observations on the ketone and adduct it is possible to measure the anodic waves of mercaptans. [Pg.25]

Claasz generated the mercaptan in situ from the disulfide. Claasz also treated a-bromo esters with the thiol and subjected the adducts to reductive cyclization, which produced the benzothiazinones.127... [Pg.160]

Synthesis of disulfides. Diethyl azodicarboxylate reacts with a mercaptan (ether, room temperature) to give a 1 1 adduct (a diethyl N-alkanesulfenylhydrazodicar-boxylate, 1). The adduct reacts in refluxing benzene (5 hrs.) with another equivalent of a mercaptan to give a disulfide. The method is particularly useful for syntheses of unsymmetrical disulfides. [Pg.341]

R2 = Me Librium). Dimethylamine, on the other hand, produced a mixture of the diazepine oxide (106 R1 = R2 = Me) together with the normal substitution product (107 R = NMe2), and piperidine, cyclohexylamine, and mercaptans formed the normal products (107 R = piperidyl, NHC6H, and SR1). The polarizability of the nucleophile appeared to be more important than its steric properties.238 The reverse transformation was brought about by dilute aqueous acid, which in the presence of an aliphatic aldehyde converted 106 (R1 = H R2 = Me) into the aldehyde adduct of 6-chloro-2-methylamino-4-phenylquinazoline 3-oxide.239 In the absence of an aldehyde, or with nitrous acid, 106 (R1 = H R2 = Me) produced 6-chloro-4-hydroxy-2-hydroxyiminomethyl-3-methyl-4-phenyl-3,4-dihydroquinazoline.240 Simi-... [Pg.51]

Tolgyesi and Fang [68] have found that alkaline amine solutions react differently with human hair. With human hair, all amines examined, including pentyl amine, compete less effectively with the amino and mercaptan residues of the hair for the dehydroalanine intermediate. As a result, more lanthionine and lysinoalanine cross-links form than amine adduct, when human hair is the substrate. This is probably because diffusion rates are slower into human hair, decreasing the effective concentration of free amine in the fibers. Therefore, these species cannot compete as effectively for the dehydroalanine intermediate therefore, lanthionine and lysinoalanine are formed. [Pg.127]

During study of the chiral thiourea 12-catalyzed sulfa-Michael addition of aliphatic thiols to nitroolefins, benzylic mercaptans were subjected to the reaction with nitrodienes (Scheme 8) [17]. Exclusive formation of 1,4-adducts was observed in moderate to good chemical yield with moderate to fair enantioselectivity. [Pg.61]


See other pages where Mercaptan adducts is mentioned: [Pg.376]    [Pg.228]    [Pg.40]    [Pg.197]    [Pg.185]    [Pg.251]    [Pg.204]    [Pg.1190]    [Pg.67]    [Pg.57]    [Pg.54]    [Pg.3090]    [Pg.311]    [Pg.35]    [Pg.51]    [Pg.57]    [Pg.1190]    [Pg.424]    [Pg.4644]    [Pg.229]    [Pg.503]    [Pg.504]    [Pg.395]    [Pg.62]    [Pg.373]   
See also in sourсe #XX -- [ Pg.776 ]




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