Tosyl isothiocyanate

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. ... 

Tosyl isothiocyanate adds to the dimethylamine or piperidine enamines of isobutyr-aldehyde to form isolable betaines 4, which in non-polar solvents are in equilibrium with (tosylimino)thietanes 520 (equation 3). 

S-alkyl-N,N,N -trialkylisothioureas 10 react with tosyl isothiocyanate to give ionic adducts 11, which sometimes undergo a [2+2] cycloreversion reaction to give N-sulfonylcarbodiimides 12 and dimethylthiourea. " ... 

Substituted quinazoline-4(3/7)-thiones 1 react with tosyl isothiocyanate with elimination of carbon disulfide to give the corresponding 4-tosylimino-3,4-dihydroquinazoline derivatives 2. ... 

In the reaction of tosyl isothiocyanate with enamines, having substituents at the j8-carbon,... 

At-Alkylimidocarbonates and imidothiocarbonates react with tosyl isothiocyanate to give crystalline ionic linear 1 1 adducts 46. Some of the adducts are labile and dissociate in solution back to the starting materials . 

Likewise, imidoyl ketenimines 153 react as 1-aza-1,3-dienes in [4-1-2] cycloaddition reactions with phenyl isocyanate to give the cycloadducts 154 (62-67 % yields) or with tosyl isothiocyanate to give the cycloadducts 155 (62-69 % yields) . ... 

Most 1,3-diazepine syntheses employ the insertion of a single carbon fragment between the two nitrogen atoms. This is further exemplified by the use of tosyl isocyanate and methyl isothiocyanate in the preparation of the bicyclic imidazo[4,5-e][l,3]diazepines 46 and the imidazo[4,5-rf][l,3]diazepines 47 respectively <96JHC855, 96JCS(P1)2257>. 

Fairly complex approaches have been used to construct thiazoles substituted with an enamine group. The cyclocondensation of l-tosyl-2,2-dichloroethenyl isothiocyanate 21 with various enamines such as 22 affords enamino substituted thiazoles such as 23 in high yields <00MI109>. 

When acrylonitrile or ethyl acrylate was used as the dipolarophile, the azomethine adducts (134) and (135) were formed no thiocarbonyl ylide addition products were isolable in refluxing toluene or xylene, although the isoindoles (136a) and (136b) derived from them were isolated. In contrast to the reactions with fumaronitrile or AT-phenylmaleimide, the azomethine adducts (134) and (135) were still present at higher reaction temperatures — almost 50% in toluene and 4-5% in xylene. Under the same reaction conditions other electron-deficient dipolarophiles like dimethyl fumarate, norbornene, dimethyl maleate, phenyl isocyanate, phenyl isothiocyanate, benzoyl isothiocyanate, p-tosyl isocyanate and diphenylcyclopropenone failed to undergo cycloaddition to thienopyrrole (13), presumably due to steric interactions (77HC(30)317). 

A related series of 5-substituted-2-amino-oxadiazole compounds have also been prepared in a one-pot procedure using a microwave-assisted cyclisation procedure (Scheme 6.26)164. Rapid preparation of the pre-requisite ureas from the mono acyl hydrazines and various isocyanates (or the isothiocyanate) was easily achieved by simple mixing. The resulting products were then cyclo dehydrated by one of the two procedures either by the addition of polymer-supported DMAP and tosyl chloride or alternatively with an immobilised carbodiimide and catalytic sulphonic acid. Purity in most cases was excellent after only filtration through a small plug of silica but an SCX-2 cartridge (sulphonic acid functionalised - catch and release) could be used in the cases where reactions required additional purification. 

A paper by Muller and Wilhelms describes the simple introduction of thiocyanate residues into the primary alcohol groups by the reaction of potassium thiocyanate with the tosyl derivative, or onto the carbonyl carbon by using the acetobromo compound. Tosyl esters of the secondary alcohols do not react under these conditions. The isothiocyanates, on treatment with sodium methoxide, yield the disulfides. 

Isothiocyanates (105) are very reactive molecules, but rather less so than isocyanates. Some are physiologically active and occur as natural products for example, allyl isothiocyanate (105) (R=CH2CH=CH2) is a major component of mustard oil and horseradish root. Isothiocyanates can be prepared by thermal rearrangement of the analogous thiocyanates (111) the latter are obtained by treatment of alkyl halides or tosylates with potassium thiocyanate (110) (Scheme 60). 

The competitive elimination (ET) and substitution (iSn2) reactions of cyclohexyl tosylate with triphenylphosphine have been examined. Triphenylphosphine is considered to be representative of neutral weak bases which have good nucleophilic afiinity for carbon, but it is a poor reagent for elimination when compared with anionic weak bases that are also good carbon nucleophiles. The reaction of triphenylphosphine with cyclohexyl bromide occurs with almost complete substitution. Tertiary phosphines react with fluorosulphonyl isocyanate and with isothiocyanates to form the zwitterionic adducts (56) and (57). 

Formation of heterocycles. Five membered heterocycles Phenacylmalononitrile underwent cyclization in acidic media to yield substituted furans 136164 and 137166. Cyclization with anilines afforded pyrroles 138166. Benzylmalononitriles have been cyclized with hydrazine or hydroxylamine to yield 3,5-diaminopyrazoles or isoxazoles, respectively 6. Aminomalononitrile tosylate can be reacted with aliphatic or aromatic isothiocyanates to yield 2,5-diaminothiazole-4-carbonitrilesi6. ... 

Tosyl isocyanate added dropwise at -5° to a soln. of dimethyl hydrogenphospho-nate in anhydrous ether, and allowed to ward to room temp, with stirring during 11 hrs. -> dimethyl p-toluenesulfonylcarbamoylphosphonate. Y 72%. F. e. s. K. D. Berlin and L. Merritt, J. Chem. Eng. Data 14, 130 (1969) diemistry cf acyl- and sulfonyl-isocyanates, isothiocyanates, and isoselenocyanates, review s. M. O. Lo-zinskii and P. S. PePkis, Russ. Chem. Rev. 37, 363 (1968),... 

The more reactive tosyl-, alkoxycarbonyl- and mercaptocarbonyl isothiocyanates undergo a [2+2] cycloaddition reaction with azomethines (R = i-Pr, CeHn, Ph) across their C=S bonds to give 1,3-thiazetidine derivatives 42 (R = 4-MePhS02-, MeSCO-, EtOCO-)22. 

Thiaziridinimines may be intermediates in the reaction of alkyl azides with aryl isothiocyanates. Thiaziridine intermediates have been suggested in the reaction of A -tosyl-suIphilimines with cyanide ion, in the decomposition of... 

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