Isothiocyanates reaction with amines

It appears, then, that isocyanate and isothiocyanate CDAs are useful in LC resolutions of amines. Several of these agents are commercially available, and many others can be readOy prepared from a variety of commercially available optically active primary amines. The stereochemical stability of these CDAs is excellent, their reaction with amines is rapid and convenient, and the derivatives are readily and sensitively detected. These reagents are likely, therefore, to enjoy continued popularity. 

Succinimidyl esters are an excellent first choice to activate amine-reactive probes, but their low solubility has led to the alternative use of sulphonyl chlorides (Figure 4.17). The resultant sulphonamide link is extremely stable, even more stable than an amide link, and will survive even complete protein hydrolysis - a property that can be exploited in protein analysis. The disadvantage of sulphonyl chlorides is that they are unstable in aqueous buffers under mildly alkaline conditions (typically the pH required for the reaction with aliphatic amine ). Hence extreme care must be taken to perform bioconjugations with sulphonyl chlorides at low temperatures (approx 4 °C). Alternatively, amine-reactive probes may be equipped with isothiocyanate traps , from which thiourea links are formed post-reaction with amine functional groups, or with aldehydes, from which Schiff sbase links can be formed with amine functional groups (Figure 4.17). 

A general scheme for synthesis of isocyanate and isothiocyanate derivatives is the reaction with amines (equation 39). This yields derivatives of urea or thiourea, however, the methods should be developed in accordance with the intended application as an analytical tool. 

Routine syntheses of glycosyl isothiocyanates, involving reaction of the corresponding hexopyranosyl bromides with potassium thiocyanate, and then-subsequent conversion to thiourea and thiosemicarbazide derivatives on reaction with amines and hydrazine, respectively, have been reported. Partially protected -D-galactopyranosylamine derivatives, e g. (25) and (26), have been obtained by reaction of the corresponding galactosyl isothiocyanate with a-aminoaceto-phenones and a-aminoacetone, respectively. In acetic anhydride, the thiourea (25) qrclised to compound (27). ... 

Chemical Properties The formation of salts with acids is the most characteristic reaction of amines. Since the amines are soluble in organic solvents and the salts are usually not soluble, acidic products can be conveniendy separated by the reaction with an amine, the unshared electron pair on the amine nitrogen acting as proton acceptor. Amines are good nucleophiles reactions of amines at the nitrogen atom have as a first step the formation of a bond with the unshared electron pair of nitrogen, eg, reactions with acid anhydrides, haUdes, and esters, with carbon dioxide or carbon disulfide, and with isocyanic or isothiocyanic acid derivatives. 

Thiophosgene reacts with alcohols and phenols to form chlorothionoformates or thiocarbonates. The most studied reactions of thiophosgene are with primary amines to give isothiocyanates and with secondary amines to give thiocarbamyl chlorides ... 

Since chiral amines are much more available than chiral isocyanates, ureas have often been obtained from reaction of an amine used as the chiral source with a stoichiometric amount of a non-chiral isocyanate [41]. Similarly, thioureas are obtained by reacting isothiocyanates with amines. The corresponding ureas and thioureas (examples in the following sections) are... 

Aminopyridotriazinones 123 were obtained from guanidines 122 in hot hydrochloric acid-dioxane solution however, yields were moderate. The intermediates 122 could be obtained from the reaction of 2-aminopyridine 120 with ethoxycarbonyl isothiocyanate, followed by treatment of thioureas 121 with amines in the presence of HgCl2 (Scheme 12) <2002JHC1061>. 

Isothiocyanates react with nucleophiles such as amines, sulfhydryls, and the phenolate ion of tyrosine side chains (Podhradsky et al., 1979). The only stable product, however, is with primary amine groups, and so TRITC is almost entirely selective for modifying s- and N-terminal amines in proteins. The reaction involves attack of the nucleophile on the central, electrophilic... 

Thioureas are most commonly prepared from reaction of isothiocyanates with amines. Also there are some reports on reactions of anime or carbodiimides with several thionating reagents. AA -Disubstituted thioureas bearing double NH groups have been developed as sensors, and as catalysts because of their hydrogen bonding ability. A,A -Disubstituted thiourea-linked sugar chains have been prepared by the reaction of isothiocyanate with amine. 

Reaction of isothiocyanate with amine gives the corresponding thioureas. Many reports are appeared.102 111 The thiourea derivatives have been prepared by reactions of isothiocyanates with arylamines (Scheme 39) and reacted with some substrates to afford heterocyclic compounds, such as 2-amino-4//-ben-zothiazine, 1,3-thiazine, 1,3-thiazinone and l,3-thiazolidin-4-one.112 115... 

Cyclic thiourea derivatives having three different types of cyclophane structure (ortho-meta, meta-meta and meta-para) and a lariat-type thiourea have been synthesized, using reaction of isothiocyanate with amine.230 Cyclic thioureas have been obtained from formaldehyde aminals and sulfur (Sg) (Scheme 77).231... 

Thus, (dimorpholinophosphoryl)formonitrile oxide undergoes 1,3-addition reactions with HC1, HI, primary and secondary amines, acylhydrazines, and even with thiourea or thiosemicarbazide (Scheme 1.13) (98). The former gives (dimor-pholinophosphoryl)isothiocyanate and urea. Those products might arise from a retro destruction of the unstable 1,3,5-oxathiazoline. The latter transforms to the isothiocyanate, the product of addition of a second molecule of thiosemicarbazide. (98). 

Saccharidic templates bearing an amino group in C-2, C-6, C-3, C-5. Generally, an amine located on non-anomeric position reacts similarly through the condensation reaction with carbon disulfide or thiophosgene, the preliminary formed isothiocyanate leads to spontaneous or base-induced cyclization into 1,3-oxazolidine- or l,3-oxazine-2-thiones, as previously mentioned. Several extensive studies are reported about the selective introduction of thionocarbamate moieties on carbohydrate scaffolds.3 22 23 320 34 38... 

A series of solid-state reactions has been explored by Kaupp et al., in which gaseous amines were reacted with aldehydes to give imines. Analogous reactions with solid anhydrides, imides, lactones or carbonates, and isothiocyanates were used to give, respectively, diamides or amidic carboxylic salts or imides, diamides, carbamic acids, and thioureas [24]. In general the yields were found to be quantitative. Ammonia and other gaseous amines, in particular methyl-amine, have also been shown to aminolyse thermoplastic polycarbonates [25]. 

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