Isothiocyanates, alkyl

Condensation of 2-phenyl-4-amino-5-benzoylthiazole with cyanamide yields the pyrimidothiazole (Scheme 88) (133) (49) 2-imino-3-aryl-4-amino-5-carbethoxy-4-thiazolines condense similarly with alkyl isothiocyanates (276). 

The reaction of 2-aminothiazoles with alkyl isothiocyanates yields 2-thiazolylthioureas (30.3, 490), otherwise usually obtained by direct heterocyclization (Chapter II. Section II.4). Other synthetic methods... 

Aryl and alkyl isothiocyanates are converted ia good yields by IF ia pyridine to thiohis(/V-trifluoromethy1 amines) (89,90) ... 

Fluotination of aromatic isothiocyanates occurs much more readily than that of alkyl isothiocyanates. Alcohols treated with IF ia DMF give 30—70% yields of their respective formates. 

Sulfoxides occur widely in small concentrations in plant and animal tissues, eg, aHyl vinyl sulfoxide [81898-53-5] in garlic oil and 2,2 -sulfinylbisethanol [3085-45-8] as fatty esters in the adrenal cortex (1,2). Homologous methyl sulfinyl alkyl isothiocyanates, which are represented by the formula CH3SO(CH2) NCS, where n = 3 [37791-20-1], 4 [4478-93-7], 5 [646-23-1], 8 [75272-81-0], 9 [39036-83-4], or 10 [39036-84-5], have been isolated from a number of mustard oils in which they occur as glucosides (3). Two methylsulfinyl amino acids have also been reported methionine sulfoxide [454-41-1] from cockroaches and the sulfoxide of i -methylcysteine, 3-(methylsulfinyl)alaiiine [4740-94-7]. The latter is the dominant sulfur-containing amino acid in turnips and may account in part for their characteristic odor (4). 

Diamines can also react with only one equivalent of isothiocyanate to form bi-functionnal amine-thiourea ligands 59-68% yields obtained for several alkyl isothiocyanates. However, reaction of phenyhsocyanate with 1,2-diamines could also lead to the formation of the guanidine derivative by cyclisation and elimination of H2S (Scheme 4) [42,43]. 

Compound 133 was synthesized by the one-pot intermolecular cyclization of ketene aminal 132 with alkyl isothiocyanate (Equation 15) <1995BML1541, 1997BML651, 2002BMC1275>. 

The cyclization to the desired head-to-tail linked bis-benzimidazoles could also be performed utilizing aryl or alkyl isothiocyanates with N, N -dicyclohexylcarbodiimidc (DCC) [82]. Upon completion, the insoluble N,N -dicyclohexylthiourea formed had to be removed by filtration and the desired PEG-bound products were precipitated by the addition of diethyl ether. The results were essentially the same as those of the cyclizations with the above mentioned aldehydes. 

The soluble polymer support was dissolved in dichloromethane and treated with 3 equivalents of chloroacetyl chloride for 10 min under microwave irradiation. The subsequent nucleophilic substitution utilizing 4 equivalents of various primary amines was carried out in N,N-dimethylformamide as solvent. The resulting PEG-bound amines were reacted with 3 equivalents of aryl or alkyl isothiocyanates in dichloromethane to furnish the polymer-bound urea derivatives after 5 min of micro-wave irradiation (Scheme 7.75). After each step, the intermediates were purified by simple precipitation with diethyl ether and filtration, so as to remove by-products and unreacted substrates. Finally, traceless release of the desired compounds by cyclative cleavage was achieved under mild basic conditions within 5 min of micro-wave irradiation. The 1,3-disubstituted hydantoins were obtained in varying yields but high purity. 

The anodic oxidation of alkyl isothiocyanates RNCS in wet acetonitrile (AN) involves the formation of two possible... 

The anodic oxidation of substituted allenes [76-79] and hetero-allenes [80-85] has been extensively studied by Becker and coworkers. Oxidation of secondary and tertiary alkyl isothiocyanates resulted in an ot-cleavage processes [77]. Primary alkyl isocyanates yielded amides and carbonyl compounds due to the nucleophilic involvement of either acetonitrile or water [80]. Primary alkyl isothiocyanates 48 afforded five-membered thiadiazolidine 49 and 50 and... 

Ammonium thiocyanate reacts with alkyl hahdes forming alkyl thiocyanates, RSCN, which may also rearrange to alkyl isothiocyanates, RNCS ... 

The experimental evidence as a whole suggests that both isothiocyanate oxides and sulfides, in the form of their salts, possess the dithiazolidine structures 153 and 155, respectively the lower alkyl isothiocyanate oxides when liberated rearrange to the 1,2,4-thiadiazolidines (152), but the higher homologs do not. In the isothiocyanate sulfides,... 

This reaction is general for the preparation of alkyl isothiocyanates in good yields thus, according to the submitters, ethyl isothiocyanate is obtained in yields of 60-70 per cent from ethylamine hydrochloride. 

This is a general method for the preparation of alkyl thioureas. Ethylthiourea, m.p. 103-106°, has been prepared from ethyl isothiocyanate in the same manner. Di- and tri-alkyl thioureas may be prepared from alkyl isothiocyanates in a similar manner by substituting an equivalent amount of an amine solution in place of the ammonium hydroxide. Thus, sym -dimethylthiourea is prepared from methyl isothiocyanate and methylamine solution. A solution of dimethylamine and methyl isothiocyanate gives trimethylthiourea. 

The reaction of 4,5-dihydro-4//-l,2,4-thiadiazine 1,1-dioxides 142, which have a leavable group in the 3-position (Y = OR1, SR1, NH2), with two molecules of an alkyl isocyanate (RNCO) produces the condensed system 143, while the alkyl isothiocyanate yields the different condensed system 145. The former reaction apparently proceeds through intermediate 144, i.e., by reaction at the 4-position. On the other hand, the first molecule of the isothiocyanate may, by analogy, react at the 2-position via a corresponding intermediate (74BSF1917). 

The reaction of alkyl isothiocyanates, RNCS, with diphenylphosphinic hydrazide (338) in benzene has been reported.308 The bis(diethylamino)[(methylthio)thiocarbon-yl]carbenium salts (339 X = I or BF4) display ambident reactivity and can react either at carbenium carbon (hard nucleophiles) or at the thiocarbonyl sulfur atom (soft nucleophiles).309 Electrochemically generated superoxide reacts with dithioic S,S -diesters (dicarbothiolates) (340 Ar = C5H3N or C6H4) to give the monocarboxylate anions in 100% yield before giving the dicarboxylate anions.310... 

Like other acid chlorides and cyanogen bromide, vinyl chloroformate brings about fission of benzylic and allylic amines e.g. hydrastine is converted into the enol lactone (145).169 Normorphine and norcodeine give substituted thioureas (146) with alkyl isothiocyanates.170... 

Rajappa and coworkers20 used isothiocyanates as a probe to examine the enaminic reactivity of nitro-substituted enamines and enediamines. The results were usually consistent with predictions based on the chemical shift of the vinyl proton and on extended Huckel calculations. However, cyclic enediamine 7 was found to be unreactive toward aryl and alkyl isothiocyanates (see Section II.A). Very recently, the same reaction has been re-examined21 and it has been found that cyclic enediamine 7 indeed reacts easily with aryl isothiocyanate to give the addition products 176 in 54-65% yield (equation 68). 

Methylsulfinyl-hexylisothiocyanate (alkyl isothiocyanate, R-N=C = S) From 6-Methylsulfinyl-hexylglucosinolate from Wasabi japonica (Japanese horseradish) (Brassicaceae) Induces GST [indirect AO]... 

Alizarin 8.1p, 9.5Ap, 13.6Dp Alizarinprimeveraside 12. Ip. Alkannin 5.7C, 9.3Fp, 9.3Gp. Alkyl-acetyl-glyceryl-phosphorocholine 5.7Gn Alkyl-isothiocyanates 13.8ZP Alkyl-lysophospholipid 8. In Allethrin I 4.2n Allethrin II 4.2n... 

By sequential treatment of the sodium alkoxides of allylic alcohols with an equimolar amount of an alkyl isothiocyanate, allylic thiocarbonimidates are obtained. These compounds undergo cyclization induced by iodine in tetrahydrofuran, or bis(collidine)bromonium perchlorate in dichloromethane, to give the corresponding Al-alkyl-2-oxazolidinones, precursors of amino alcohols, in good yield. The cyclization of thiocarbonimidates prepared from 2-cyclohexenols proceeded with total regio- and stereoselectivity and a single diastereomer was recovered from the reaction mixture138 140. 

Alkyl isothiocyanates also afford alkythioureidopyiimidines, usually by reaction in aqueous alkali, and these may be cyclized by hydrochloric acid to produce 9-alkyl-8-thioxopurines. In this manner 5-aminobarbituric acid furnished 9-alkyl-8-thiouric acids (2lLA(423)242). 8-Thiouric acid (300) was also obtained by formation of a thioureido-pyrimidine in situ from the cyanamidopyrimidine (301 Scheme 112) (02CB2563). 

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