Dimeric isothiocyanate

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... 

A typical cyclization reaction starting from a 3-aminopyrazole is the transformation of 255 <2000BML821 >. This compound was treated first with ethoxycarbonyl isothiocyanate followed by sodium methoxide to yield a cyclic intermediate which was methylated by methyl iodide to give the stable product 256. In the cases of the synthesis of 257 <1995PHA675>, the dimeric 258 <2005JHC975>, the azo-substituted 259 <2001JCM439>, and the diaryl... 

In the case of thiazoline-2(3//)-thiones, the mesoionic thiazolo[2,3-h][l,3,4]thiadiazoles are obtained by two different routes (Scheme 65). On the one hand, thione 166 reacts with isothiocyanate via intermediate 167 and with a second equivalent isothiocyanate to afford the mesoionic 168 on the other hand, in the presence of isocyanate, the thione preferentially dimerizes 167 with the open-chain carbodiimide 169 to give the mesoionic 170. Addition of acid with removal of an amine group converts 170 into the symmetric heteroaromatic amine (171) (88CB1495 92T1285). The related transformation of an imidazoline into 1,3,4-thiadiazoles has also been described (90T4353). 

Treatment of diarylphthalins, obtained by reduction of diarylphthalides, with sulfuric acid results in rearrangement to yield a mixture of benzo[c]furans and anthrones (34JA1406). When diarylphthalins (441) were reacted with sulfuric acid the benzo[c]furans (442) were isolated. A dimeric benzo[c]furan (443) was obtained when the phthalin (444) was treated with acetic anhydride or phenyl isothiocyanate. 

Heterocyclic substituted carbodiimides can undergo dimerization by a [2-1-4] cycloaddition process. For example, di-2-pyridylcarbodimide 194, generated in situ in the reaction of an iminophosphorane with CS2 and an isothiocyanate, affords the cyclodimer 195,... 

Another goitrogenic compound in cabbage is thiocyanate ion (107) which results from breakdown of indolylmethyl isothiocyanate produced from the corresponding glucosinolate, glucobrassicin (97,106,108) (reaction G). The 5-hydroxymethylindole thus produced can dimerize to 3,3 -diindolylmethane or form a complex (ascorbigen) with ascorbic acid (perhaps a novel type of feedback inhibition of ascorbate-dependent... 

PAHs polycyclic aromatic hydrocarbons. FITC fluorescein isothiocyanate. DNS dansyl halide. OPA o-phthaldialdehyde. NBD 4-clair-7-nitrobenz-2-oxa-1,3-diazole. YOYO-1 benzoxazolium-4-quinolinium dimer. NAD" nicotinamide adenine dinucleotide. 

In the case of the reaction of 1 with COS the intermediate silathione dimerizes to the dithiadisiletane derivative III. In the reaction of 1 with RNCS the silathione does not dimerize, but it is trapped by the respective isothiocyanate in form of the formal [2+2] cycloaddition product IV. The intermediates Cp 2Si=X (X = O, S) (2) could not be isolated but derivatized by trapping reactions. In the presence of t-butyl methyl ketone the silanone (Cp 2Si=0) reacts in an ene-type reaction [9] to give the addition product 5 the silathione (Cp 2Si=S) is transformed in a first step to an addition product analogous to 5, in a further step this species reacts with 1 in an oxidative addition process to form the final product 4 (see Scheme 2). 

Cycloaddition of a,3-unsaturated ketones, acyl ketenes, acyl, thioacyl, imidoyl and vinyl isocyanates, as well as the corresponding isothiocyanates, to the C=C bond of vinylidenephosphoranes leads to the formation of six-membered heterocycles carrying an exocyclic ylide function e.g. equation 117). In some instances the mentioned thioisocyanates, however, may undergo [2 + 2] cycloaddition at the C=S bond. Interestingly N-aryliminovinylidenetriphenylphosphoranes dimerize in a [4 2] cycloaddition on heating alone. 

Aminothienopyrimidinones 41 were synthesized by cyclization of vic-cyanothienylureas 42 generated in situ by the reaction of 2-amino-3-cyanothiophenes 30 with isothiocyanates (1985CB4473) or urea (1990MI1). Compound 41 with R3 = H exists predominantly as the tautomeric 4-NH form. The reactions with isothiocyanates are accompanied by dimerization as a side process (1991JPR229). 

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