Acyl isothiocyanate

The reaction of the enamines of cyclic ketones with alkyl isocyanates, acyl isocyanates, phenyl isothiocyanates, and acyl isothiocyanates has also been reported 112). The products are the corresponding carboxamides. The products from the isothiocyanates have been utilized as intermediates in the preparation of various heterocyclic compounds 113). 

N-Substituted amides can be prepared by direct attack of isocyanates on aromatic rings.The R group may be alkyl or aryl, but if the latter, dimers and trimers are also obtained. Isothiocyanates similarly give thioamides. The reaction has been carried out intramolecularly both with aralkyl isothiocyanates and acyl isothiocyanates.In the latter case, the product is easily hydrolyzable to a dicarboxylic acid this is a way of putting a carboxyl group on a ring ortho to one already there (34 is... 

Other thietane derivatives have been obtained by isomerization of nitrogen-containing heterocycles. The reaction of an acyl isothiocyanate (RCONCS) with diphenyldiazomethane gave 20 and this isomerized in solution to the tetraphenyl-3-thietanone 21 <96BSB253>. Additionally, the isoxazolidine 22 was converted into 23 by the action of trimethylsilyl iodide and zinc iodide <96H1211>. 

Biphilicylides 117 can enter in cyclocondensations with carboxylic acid chlorides, carbon disulfide, and acyl isothiocyanates [126]. Certain corresponding heterocychc products 118 obtained are described for the first time (Y =N(CO)Ph Y=S) and are precursors of the new l-(2-phenylthiazol-5-yl)-5-phenyltetrazole 119 (Scheme 33). 

Wilson LJ, Klopfenstein SR, Li M. A traceless linker approach to the solid phase synthesis of substituted guanidines utilizing a novel acyl isothiocyanate resin. Tetrahedron Lett 1999 40 3999 -002. 

In this case, the acidic species RCOX is a hard acid and reacts with the nitrogen end of SCN to form an acyl isothiocyanate. The soft methyl group bonds to the S atom and forms methyl thiocyanate. Consider the reactions of NC)2 ... 

The conversion of acyl isothiocyanates 47 with sodium azide leads to thiol-functionalized tetrazole derivatives such as 48 (Scheme 9) <1995PJC1022>. The reaction of 48 with chloro acetonitrile leads to an intermediate 49 that reacts in... 

The reactions of Meldrum s acid (421) and acyl isothiocyanates in DMSO in the presence of lithium hydride at ambient temperature for 2-3 hr gave the lithium salts (457), which were alkylated by treatment with alkyl halide for 5 hr to afford isopropylidene (acylamino)(alkylthio)methy-lenemalonates (458) in 20-90% yields (87ZC68). 

Alkyl and glycosyl isocyanates and isothiocyanates are produced in good yield under phase-transfer catalytic conditions using either conventional soluble catalysts or polymer-supported catalysts [32, 33]. Acyl isothiocyanates are obtained under similar conditions [34]. A-Aryl phosphoramidates are converted via their reaction with carbon disulphide under basic conditions into the corresponding aryl isothiocyanates, when the reaction is catalysed by tetra-n-butylammonium bromide [35]. 

Aqueous KSCN (33%, 33 ml, ca. 0.11 mol) is added dropwise over ca. 25 min to the acid chloride (43 mmol) and TBA-Br (0.55 g, 1.7 mmol) in PhH (20 ml) and the mixture is stirred at room temperature for ca. 2 h. The aqueous phase is separated and extracted with PhH (3x5 ml). The dried (MgS04) organic solutions are fractionally distilled to yield the acyl isothiocyanate. 

Acyl isothiocyanates (RCON=C=S) and sulfenes (RCH=S02) react with thiatriazolines to give C=S adducts following path (b) <78JOC495i>. 

Aryl and acyl isothiocyanates were also found to react with alkyl azides, but yield thiatriazoline-5-imines only as elusive intermediates which are transformed in situ into a series of bisadducts after loss of nitrogen. Interestingly, L abbe et al. have found that picryl isothiocyanate is an exception to this and reacts smoothly with alkyl azides to yield 4-alkyl-5-picrylimino-l,2,3,4-thiatriazolines (177) which are stable below 100°C <90JHC1059>. Kinetic experiments indicate that the reaction between picryl isothiocyanate and alkyl azides most likely is concerted as no significant solvent effect was observed. 

A second type of synthetic route to meso-ionic l,3,4-thiadiazol-2-imines (247) is based on the acid-catalyzed reaction of N-thioacylhydrazines (232) with aryl isothiocyanates (Ar-NCS). " This reaction yields the s ts (248) as precursors of the meso-ionic heterocycles (247). An interesting variant upon this route involves the reaction between IV-thioacylhydrazines (232) and acyl isothiocyanates (RCO-NCS). This leads to the meso-ionic heterocycles 247, R = COzEt, CONMej, COMe, COCMe, COAr, and SOjPh. The investigation of these compounds by X-ray photoelectron spectroscopy is a good example of the application of this physical method for the examination of meso-ionic compounds. 

Wilson, L. J. Lin, M. A Traceless Linker Approach to the Solid Phase Synthesis of Substituted Guanidines Utilizing a Novel Acyl Isothiocyanate Resin, Tetrahedron Lett. 1999, 40, 3999-4002. 

Isothiocyanates can be prepared from support-bound primary amines by treatment with thiophosgene [14] or synthetic analogs thereof (Entry 5, Table 14.2). In an alternative two-step procedure, the amine is first treated with CS2 and a tertiary amine to yield an ammonium dithiocarbamate, which is subsequently desulfurized with TsCl or a chloroformate (Entry 6, Table 14.2 Experimental Procedure 14.1). Highly reactive acyl isothiocyanates have been prepared from support-bound acyl chlorides and tetra-butylammonium thiocyanate (Entry 7, Table 14.2). These acyl isothiocyanates react with amines to give the corresponding 7V-acylthiourcas, which can be used to prepare guanidines on insoluble supports (Entry 6, Table 14.3). 

Reaction of various aromatic or heteroaromatic diamines with iV-acyl isothiocyanates gave the corresponding benzo- or heterocycle-fused l,3,5-triazepine-2-thiones, for example, 16 (Figure 3) from 5,6-diamino-1,3-dimethyl-uracil and D-gluconyl isothiocyanate <1981CPB1832>. Cycloaddition of iVjiV -disubstituted ethylenediamines with bis(isocyanato)dimethylsilane or bis(isothiocyanato)dimethylsilane followed by treatment with 1,1 -carbonyldi-imidazole or 1,1 -thiocarbonyldiimidazole afforded a series of 1,5-disubstituted l,3,5-triazepine-2,4-diones, -2,4-dithiones, and 4-oxo-l,3,5-triazepine-2-thiones <1980AGE327>. 

Acyl isothiocyanates react with alkyl azides, presumably to give the primary products (45) which have not been isolated so far (equation 20). Reaction of (45) with a second mole of acyl isothiocyanate affords 1,2,4-dithiazolidine (46) and 1,2,4-thiadiazole (47). The formation of these products may be rationalized along the same principles as discussed above (79BSB245). 

Alkyl (or acyl) isothiocyanates have proved to be useful intermediates for thioxopurine synthesis and can also be used to produce guanine derivatives. Methyl isothiocyanate and... 

Oximes have been formed from l,2-dithiole-3-thiones and hydroxyl-amine.240 l,2-Dithiole-3-thiones react with acyl isothiocyanates to give 165.241... 

Triazolo[3,4-Z>]thiadiazolium salts (450) are prepared by three methods (1) acidic cyclization of N-acylaminothiones 449, (2) the action of PCI5 on Schiff bases 451, and (3) interaction of phosphazo compounds 452 with acyl halogenides. On the basis of phosphazo compounds and acyl isothiocyanates, betaines 453 have also been synthesized (86LA1540). 

Dihydro-1,3-oxazines (398) are cyclic intermediates in the synthesis of a-amino-y-oxo acid esters by reaction of acyliminoacetates with enamines derived from six-membered ketones . Sulfur-containing heterocycloadducts 399 and 400 have been prepared by [4 -I- 2] cycloaddition of enamines to heterocumulenes like thioacyl isocyanates and acyl isothiocyanates . 

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