Isothiocyanation reagents

A-Thiazolyl a-amino acids 56 have been prepared. The preferred route to these compounds would utilise the Hantzsch synthesis, however in this case the in situ formation of the required thiourea derivatives of a-aminoacids 52 failed. A variety of isothiocyanate reagents were tried, with the result being either no reaction, decomposition or the corresponding thiohydantoin 53. A modified version of the Hantzsch synthesis was developed. If the bromoketone 54 is initially treated with sodium thiocyanate an a-thiocyanatoketone 55 is formed, subsequent addition of the amino acid ester 51 yields A-thiazolyl a-amino acids 56 <00T3161>. 

Baxendale et al. (2008) reported a bifurcated approach to the synthesis of thiazoles and imidazoles by coupling a glass microreactor and a packed-bed reactor to achieve a base-mediated condensation reaction. As Scheme 32 illustrates, reactions focused on the use of ethyl isocyanoacetate 123, as the cyanide source, with variations made via the isothiocyanate reagent, as illustrated in Table 13. 

N-terminal amines in proteins. The reaction involves the attack of a nucleophile on the central electrophilic carbon of the isothiocyanate group. The resulting electron shift creates a thiourea linkage between FITC and the biomolecule. FITC is water soluble above pH 6.0, and isothiocyanate reagents are reasonably stable in aqueous solution for short periods but degrade over time. The main applications of FITC are as follows ... 

Rydberg, P. Method for analyzing N-terminal protein addncts nsing isothiocyanate reagents. PCX Int. Appl. WO 2005101020, 2005 Chem. Abstr. 2005,143,418626. 

Formamidinoyl isothiocyanates (157) combine with 2-aminothiazoles the ring nitrogen attacks the spC part of the electrophilic reagent (312) further reaction then yields aza-condensed thiazolo-s-triazines (158) (Scheme 99) (313). Mesoionic S-alkvlthiazolo[3.2-fl]-i-tria2ine-5,7-diones (159) are obtained when 2-alkylaminothiazoles react with phenoxycar-bonyl isocyanate (304). 

The most used EIA reagents conjugate a fluotophote such as fluorescein-isothiocyanate (EITC) or thodarnine—isothiocyanate to antibody (or antigen) free amino groups. Examples of other commonly used fluotophotes for EIA and their spectral characteristics ate presented in Table 3. EIA assays ate available in sandwich and competitive formats similar to EIAs. Unlike EIA kits which can be used directly with visual color deterrnination, EIAs require a fluorometer, and thus ate primarily laboratory-based. 

AletalHydrides. Metal hydrides can sometimes be used to prepare amines by reduction of various functional groups, but they are seldom the preferred method. Most metal hydrides do not reduce nitro compounds at all (64), although aUphatic nitro compounds can be reduced to amines with lithium aluminum hydride. When aromatic amines are reduced with this reagent, a2o compounds are produced. Nitriles, on the other hand, can be reduced to amines with lithium aluminum hydride or sodium borohydride under certain conditions. Other functional groups which can be reduced to amines using metal hydrides include amides, oximes, isocyanates, isothiocyanates, and a2ides (64). 

Aryl isothiocyanates can be prepared by the action of thio-phosgene on the arylamine (this reaction fails with naphthyl compounds), by fission of a 5ym-diaryIthiourea with acidic reagents (this reaction involves the loss of half the amine used), and by the decomposition of an ammonium aryldithiocar-bamate (low yields are reported for naphthyl and other compounds).The procedure described here is that of Baxter, Cymerman-Craig, Moyle, and White. ... 

The use of UV adsorption enhancers as reagents that introduce a UV chromaphore into a molecule that is transparent in the UV wavelength range has already been briefly discussed. The two most common reagents are the phenyl and methyl isothiocyanates. These reagents react with amino acids to form thiodantoins. 

When the reagent is the thiocyanate ion, S-alkylation is an important side reaction (10-43), but the cyanate ion practically always gives exclusive N-alkylation. ° Primary alkyl halides have been converted to isocyanates by treatment with sodium nitrocyanamide (NaNCNN02) and m-chloroperoxybenzoic acid, followed by heating of the initially produced RN(N02)CN. ° When alkyl halides are treated with NCO in the presence of ethanol, carbamates can be prepared directly (see 16-7). ° Acyl halides give the corresponding acyl isocyanates and isothiocyanates. For the formation of isocyanides, see 10-111. 

Isonicotinic acid hydrazide reagent 318 Isoprenaiine 395,396 Isoprenoid compounds 44 Isopulegol 59 Isoquercitrin 279, 280, 323 Isoquinoline alkaloids 46, 66, 262 Isorhamnetin 323 Isothiazolones, microbiocidal 45 Isothiocyanates 75 Isotopes, j8-radiation-emitting 41 -, detection limits 41 Itaconic acid 61... 

The phosphinic isocyanates (116) and isothiocyanates (117) react with oxygen, nitrogen, and phosphorus nucleophiles by attack at carbon rather than phosphorus. Phenyl phosphonodichloridate has been recommended as a useful reagent for the activation (presumably by mixed anhydride formation) of carboxylic acids for conversion to amides and hydrazides. ... 

R)-(+)-a-methoxy-p-nitrobenzylamine (VIII), acid chloride form of (VII) (IX), (+)-camphor-lO-sulfony. hloride and (X), (+)-neomenthyl isothiocyanate. Where not ex.,. i.icitly stated the reagent must be in a single enantiomeric form to be of use as a resolving agent. 

Muramoto K, Nokihara K, Ueda A, Kamiya H (1994) Gas-phase microsequencing of peptides and proteins with a fluorescent Edman-type reagent, fluorescein isothiocyanate. Biosci Biotechnol Biochem 58 300-304... 

Along with epi-eudesmanes, 25-27, alloaromadendranes 58-60 were separated from the chloroform solubles of a methanol extract of A. cannabina [36], As was the case with axisonitrile-2 (53), extensive spectroscopic analyses including Eu(fod)3 shift reagent experiments in XH- and 13C NMR permitted assignment of relative stereochemistry. Acanthella pulcherrima was also a source of isothiocyanate 59, although both isonitrile and formamido compounds appear to be absent [20],... 

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