Methyl isothiocyanate, reaction with

Contrasting with the reported formation of fused [l,3,4]thiadiazole rings in the course of the reaction of 3-substituted-4-amino-5-thio-47/-[l,2,4]triazoles 83 with various isothiocyanates (cf. Section 11.07.8.3, Table 3), the reactions with methyl isothiocyanate and with phenylisocyanate afford 3,7-disubstituted-6,7-dihydro-57/-[l,2,4]triazolo[4,3-f] [l,2,4]triazole-6-thiones 110 and -triazole-6-ones 111, respectively (Equation 29) <1986MI607, 1992IJB167>.The same reaction of 4-amino-l-methyl-3,5-bis(methylthio)[l,2,4]triazolium iodide 112 with aryl isothiocyanates yields the mesoionic compounds 113 (Equation 30) <1984TL5427, 1986T2121>. 

Nitenpyram, from Takeda Chemical Industries, is accessible by starting from l,l-bis-(methylsrdfanyl)-2-nitroethene via sequential aminolysis with methyl-amine and 2-chloro-5-(ethylaminomethyl)pyridine, in either order (a). [150, 151] Alternatively, 2-chloro-5- (ethylaminomethyl)pyridine may also be reacted with methyl isothiocyanate, to give the corresponding thiourea this then gives the active agent by S-methylation and reaction with nitromethane (b). 

The reaction of aliphatic isothiocyanates with alkylene oxides is more complex. For example, methyl isothiocyanate reacts with ethylene oxide in the presence of a tertiary amine catalyst at 20-90 °C to give trimethylthioisocyanurate. When the reaction is conducted at 90 °C, in the presence of tetraethylammonium bromide, the spirotriazine derivative 88 is obtained . 

A phenyl guanidine analogue is readily prepared by first I i acting 2-imino-]i-methylpyrrolidine with phenyl isothiocyanate III give synthon 21, This is next -methylated with methyl io-illcle to give 16 which itself, on reaction with pyrrolidine, is... 

In the reaction of 1 with methyl or phenyl isothiocyanate, the dithiasiletanes 76 or 77 were formed, following a pathway comparable to that observed for the reaction of 1 with carbon dioxide (see Scheme 28). In the case of the reaction with phenyl isothiocyanate, more drastic conditions... 

Similarly, the reaction of cyclic nitrones 187 with methyl isothiocyanate gives tetrahydroimidazo[l,5- ][l,2,4]oxa-diazol-2(l//)-thiones 129 (Equation 81) <2003PS(178)881, 2004MI7>. 

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]. 

Amidines are converted into 1,2,4-thiadiazoles by reaction with isothiocyanates, iminosulfenyl chlorides, di- and trichloromethyl sulfenyl chlorides, and carbon disulfide in the presence of sulfur <82AHC(32)285> for example, 5-mercapto-3-methyl-l,2,4-thiadiazole (205) is obtained by the treatment of acetamidine with carbon disulfide and sulfur under basic conditions (Equation (29)) <85JAP85255783>. A useful method for the synthesis of 5-chloro-l, 2,4-thiadiazole (206) (R = 6-methyl-2-pyridyl) involves the reaction of amidines with trichloromethylsulfenyl chloride (Equation (30)) <91JAP9183590>. 

Oxathiazolidin-3-imine (93) possesses a thioimidate moiety similar to 4-methyl-5-phenyl-imino-l,2,3,4-thiatriazoline (70) and is capable of undergoing cycloaddition-elimination reactions with isothiocyanates to give identical products, however at a much higher rate. Acetone can therefore be used as solvent to catalyze this kind of reaction of thiatriazolines. 

A successful method for preparing 1,3-thiazetidines is the cycloaddition of carbodiimides with isocyanates. The cycloadduct 151 was derived by the interaction of carbodiimide 152 and tosyl isothiocyanate . Reaction of 152 with methyl or phenyl isothiocyanate preferentially leads to iminotriazine-thiones. Cycloaddition between aryl isothiocyanates and dicyclohexylcar-bodiimide produced 153. ... 

Phenyl isothiocyanate reacts less readily with alkynyllithium than methyl isothiocyanate. The thioamide from the reaction of CHjC=CLi with PhN=C=S is not easy to obtain in a crystalline state. 

Zirconium and hafnium dialkylamides are highly reactive compounds. They undergo (i) protolytic substitution reactions with reagents such as alcohols, cyclopentadiene and bisftrimethylsilyOamine 63 64 (ii) insertion reactions with C02, CS2, COS, nitriles, phenyl isocyanate, methyl isothiocyanate, carbodiimides and dimethyl acetylenedicarboxylate 69-72 and (iii) addition reactions with metal carbonyls.73 These reactions are summarized with reference to Zr(NMe2)4 in Scheme 1. 

Methyl isothiocyanate has been prepared from methyl thiocyanate by rearrangement with heat1 and from A, A /-dimethyl-thiuramdisulfide by the action of iodine 2 or by heating with water or alcohol.3 The most useful method of preparation has been the reaction of methylamine with carbon disulfide to form methyl-... 

Silanethione 80 was also postulated as an intermediate in the reaction of silicocene 41 with isothiocyanates (room temperature/toluene/16 h for methyl isothiocyanate and 65 °C/toluene/5 h for phenyl isothiocyanate), which resulted in the formation of the corresponding intermolecular [2 + 2] cycloadducts (82 and 83) of 80 with the isothiocyanates (Scheme 30)41a b. Under even more drastic conditions (100°C/toluene/20 h), the reaction of 41 with phenyl isothiocyanate gave the five-membered heterocycles 84, which is most likely produced by a second attack of the silicocene 41 on the initially formed [2 + 2] cycloadduct 83 (Scheme 30). 

The, S n2 reaction between lithium isothiocyanate ion pair and methyl fluoride has been calculated at the MP2(full)/6-31H-G //HF/6-311- -G level of theory in the gas phase and in acetone using the PCM model.108 Both the gas phase and acetone reactions occur with inversion, rather than retention, of configuration. However, the transition states and products are different in the gas phase and in solution methyl thiocyanate is formed in the gas phase by transition state (72) whereas methyl isothiocyanate is formed much more slowly in acetone via the looser transition state (73). 

In general, benzimidazole-2-methyl carbamate derivatives (28) can be synthesized by the reaction of an appropriate diamine (26) with 1,3-dicarbo-methoxy-5-methylisothiourea (27) [43], This is the most general and economic synthesis for benzimidazole carbamates. However, the same reaction was less than satisfactory when the aza analogues of o-phenylenediamines (29) were used. In order to synthesize the aza analogues of mebendazole (2) or flubendazole (3), the reactions of methoxycarbonyl isothiocyanate (30) with a wide variety of diamines such as 3,4-diaminopyridines, 4,5-diaminopyrimi-dines, o-phenylenediamines have been investigated in the presence of dicyclo-hexylcarbodiimide [44, 45] and were found to be quite successful in the synthesis of carbamates (31). 

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