Amine-Thiol

The dibenzosuberyl ether is prepared from an alcohol and the suberyl chloride in the presence of triethylamine (CH2CI2, 20°, 3 h, 75% yield). It is cleaved by acidic hydrolysis (1 N HCl/dioxane, 20°, 6 h, 80% yield). This group has also been used to protect amines, thiols, and carboxylic acids. The alcohol derivative can be cleaved in the presence of a dibenzosuberylamine. ... 

Me3Si)2NH, Me3SiCl, Pyr, 20°, 5 min, 100% yield. ROH is a carbohydrate. Hexamethyldisilazane (HMDS) is one of the most common sily-lating agents and readily silylates alcohols, acids, amines, thiols, phenols, hydroxamic acids, amides, thioamides, sulfonamides, phosphoric amides, phosphites, hydrazines, and enolizable ketones. It works best in the presence of a catalyst such as X-NH-Y, where at least one of the group X or Y is electron-withdrawing. ... 

TBDMSCl, imidazole, DMF, 25°, 10 h, high yields. This is the most common method for the introduction of the TBDMS group on alcohols with low steric demand. The method works best when the reactions are mn in very concentrated solutions. This combination of reagents also silylates phenols, hydroperoxides, and hydroxyl amines. Thiols, amines, and carboxylic acids are not effectively silylated under these conditions. ... 

Autocatalysis may arise when the nucleophilic atom of the reagent is bound to a hydrogen atom which is eventually eliminated during the reaction. This occurs with neutral reagents such as primary or secondary amines, thiols, and alcohols. If the displaced group (usually an anion) is a sufficiently weak base, the proton is effectively transferred to any basic reactant. Hence, the best known examples of autocatalysis involve chloro-A-heteroaromatic compounds as the substrates. 

Polyazetidine prepolymer may be cross-linked in aqueous solution by reaction with amine, thiol, hydroxyl, carboxylic add or other polyazetidine groups. Cross-linking occurs upon water removal, heating or by changing to a basic pH. The immobilised cell/polymer composition may be prepared in the form of membranes, fibres, tubes or beads. 

The nucleophilic displacement reactions with azide, primary amines, thiols and carboxylatc salts arc reported to be highly efficient giving high (>95%) yields of the displacement product (Table 9.25). The latter two reactions are carried out in the presence of a base (DBU, DABCO). Radical-induced reduction with tin hydrides is quantitative. The displacement reaction with phenolates,61j phosphines,6M and potassium phthalimide608 gives elimination of HBr as a side reaction. 

It may be noted that the additions of protonic molecules HA (alcohols, amines, thiols, etc. see Section III,C) to isocyanides may be related to these reactions, in the formalistic sense anyway, since they involve additions of A (in conjunction with H+) to the isocyanide. In a few instances the additions of HA can be accomplished by adding first A" and then H to the reactant species. However, no studies on HA additions have yet elucidated a mechanism for these reactions, so to draw a conclusion on the similarities of these reactions on mechanistic grounds is not appropriate. Because of this, and also for convenience, these subjects will be treated separately. 

In a similar way, lipases catalyze Michael addition of amines, thiols [110], and even 1,3-dicarbonyl derivatives [111, 112] to a,/ -unsaturated carbonyl compounds (Scheme 5.21). 

The syntheses described in the preceding section can be performed using as stabilizers the classical ligands of organometalhc chemistry (e.g., amines, thiols, or phosphines) instead of polymers. The amount of ligand added allows control of the particle growth and therefore the size. 

The organometalhc approach allows control of the surface. It is therefore possible to prepare species displaying a clean surface able to adsorb small molecules (CO, H2) or large Hgands (phosphines, amines, thiols, polyden-tate ligands, etc.). 

T. F. McCallum, III and B. Weinstein. Amine-thiol chain transfer agents. Patent US 5298585, 1994. 

There are a few isolated cases of the addition of amines, thiols, carboxylic acids, and a phosphorus ylide to doubly bonded germanium compounds. Again, the reactions are regioselective, with the nucleophilic portion of the weak acid adding to the germanium and the proton adding to the heteroatom. 

Amines, thiols, eOH (p. 226), etc., will also add to the 0-carbon atom of 0-unsaturated carbonyl compounds and esters, but the most important reactions of C=C—C=0 systems are in Michael reactions with carbanions reactions in which carbon-carbon bonds are formed. A good example is the synthesis of l,l-dimethylcyclohexan-3,5-dione (dimedone, 100) starting from 2-methylpent-2-ene-4-one (mesityl oxide, 101) and the carbanion 0CH(CO2Et)2 ... 

Figure 13.9 Epoxy-containing silane coupling agents form reactive surfaces that can be used to couple amine-, thiol-, or hydroxyl-containing ligands.

Glycosylation Alcohols/phenols Carboxylic acids Amines Thiols Glycosyltransferases a- or //-glycosides... 

Glucuronidation Alcohols or phenols Carboxylic acids Amines Thiols Glucuronyltransferases (UDP-glucuronic acid) a- or 8-Glucuronides... 

Glucosylation Alcohol or phenol Carboxylic acid Amines Thiols Glucosyltransferases (UDP-glucose) a- or j8-Glucosides... 

Nucleophilic displacement, for the synthesis of Amines, thiols, halides, azides, acetates [204, 205]... 

Nucleophilic additions of alcohols, amines, thiols, and selenols to Group 8 buta-trienylidene intermediates [M]=C=C=C=CR2 have also been used in the preparation of stable heteroatom-conjugated allenylidene complexes. Thus, activation of trimethylsilyl-l,3-butadiyne HC=C-C=CSiMe3 by the iron(II) complex [FeClCp (dppe)], in methanol and in the presence of NaBPh4, resulted in the high-yield formation of the methoxy-allenylidene [FeCp =C=C=C(OMe)Me ... 

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