From Isocyanide Dichlorides

The isocyanide dichlorides are particularly attractive 1,1-bielectrophiles, and the N-sulfonyl derivative (138) underwent reaction with the iV-hydroxythioamide (137) to give the 1,3,5-oxathiazole derivative (139) (71AP763). Yields varied from 62% for R = Me and were slightly less for R = Ph (57%) and R = p-MeOC6H4 (50%). 

A guanidine obtained from a pentafluorophenyl isocyanide dichloride and aniline is cyclized to a tetrafluorobenzimidazole [106] (equation 92). 

Thermolysis of the formamidrazone 590, obtained from the reaction of hydrazine 488 with Vilsmeier salt 589, at 200°C or on boiling in nitrobenzene led, by intramolecular transformation, to the triazolo[4,3-c]pyrimidine 591 (90T3897). Aryl isocyanide dichlorides reacted with 488 in the presence of Et2N to give 3-anilinotriazolopyrimidines (592) (Scheme 117). 

A direct approach to 3-aryl-2-chloro-4-iminothieno[2,3-d]pyrimidines 65a from A-aryl isocyanide dichlorides and o-aminocarbonitriles 48 was devised by Shishoo and Jain (92JHC883). 3-Aryl-4-imino-2-methylthieno [2,3-rf]pyrimidines 65b were obtained by heating a mixture of 2-acetyl-aminothiophene-3-carbonitriles 64a, phosphorus pentoxide, a primary ary-lamine hydrochloride, and /V,7V-dimethylcyclohexylamine hydrochloride in a molar ratio 1 6 4 4, at 160°C (88CS195 91EUP452002). Following similar reaction conditions but adding 8 parts of water to this reaction mixture... 

Isocyanide dichlorides, formally imines derived from phosgene, react in a manner similar to that of phosgene (above) except that 2-amino-l,3,4-oxadiazole derivatives, instead of oxadiazolin-5-ones, are produced (Scheme 15) (71CC1223,81AP193,73CHE1216). 

Syntheses from Acid Hydrazides with Phosgene, Thiophosgene, Carbon Disulfide, or Isocyanide Dichlorides... 

This phenomenon of these molecules was first discovered through derivatives of 1,3-4,6-tetraphosphahexa-l,5-diene. These derivatives can be synthesized from organyltrimethylsilylphosphanes and phosgene or isocyanide dichlorides. Primarily 1,3-diphosphapropenes, which can be isolated, are formed and then react further with phosgene or isocyanide dichlorides, eliminating CO or isocyanide, respectively, and halosilane, and through oxidative combination of the two phos-... 

A guanidine derivative 43 is obtained in 60% yield from pentafiuorophcnyl isocyanide dichloride (42) and aniline. ... 

Amidines with a more complicated substitution pattern have been prepared from amidines by alkylation—either at nitrogen or at nitrogen substituents. - Variations at these positions have been achieved by heteroarylation, acylation,vinylation or carboxylation with phosgene, thio-phosgene, isocyanide dichlorides or isothiocyanates. Some interesting amidines, e.g. (347)-(3S2) (Scheme 59), have been prepared in this manner. The amidine skeleton can also be varied by halogen-ation, - hydrolysis, isomerization or catalytic hydrogenation or other addition reactions if there are C=—C double bonds present as in (353 equation 173) for example. ... 

The scope of the synthesis is further extended by the use of isocyanide dichlorides (199) their condensation with iV-methyl-iV-thiobenzoyl-hydrazine (198) in boiling chloroform yields crystalline thiadiazolium chlorides (200), which are converted by ammonia in chloroform into the mesionic 1,3,4-thiadiazoles (201) e.g. anhydro-4-methyl-5-phenyl-2-phenylamino-l,3,4-thiadiazolium hydroxide). Isomerization to mesionic 1,2,4-triazoles (202) occurs in hot ethanol, or under the influence of phenyl isocyanate in benzene. The two mesionic systems (201) and (202) may be distinguished by their mass spectra. Both isomers show a molecular ion, and a common fragment ion, MeN CPh, but they are differentiated by the fragments Ph—C=NR arising from (202) and by Ph—C S from (201). ... 

A simplified procedure for the preparation of phenyl isoselenocyanate involves the reaction of phenyl isocyanide dichloride with sodium selenide, generated in situ from elemental selenium and sodium borohydride, followed by the addition of one equivalent of sodium hydroxide (Scheme 55)/ ... 

The same reaction products are obtained from epoxides and TMS-CN in the presence of aluminum al-koxides, samarium, cerium or lanthanum chlorides as well as titanium tetraisopropanoate, which may all be considered comparatively hard Lewis acids. On the other hand various groups demonstrated that softer Lewis acids like zinc, tin and palladium dichloride may give rise to isocyanides (Scheme 15). 

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