Azirines, reaction with isothiocyanates

Azirines, reaction with isothiocyanates, 15 Azo dye, 156-168. See also Dyes Azothiazoles, 105, 153, 170, 271-274 analytical applications, 107 by diazo coupling, 105 dyes, 107 IR spectra of, 107... 

In the reaction of 3-dialkylamino-2,2-dimethyl-2H-azirines 143 with isothiocyanates carbodiimides 144 are formed in high yields. The obtained carbodiimides are in equilibrium with a zwitterionic form 145. ... 

The reaction of azirines (114) with benzoyl isothiocyanate has been discussed in terms of a (2 + 2)-cycloaddition of the azirine with the carbon-sulfur double bond, followed by rearrangement to the 2-benzamidothiazole (116).IU Experimental evidence for the formation of the (2 + 2)-cycloadduct (115) has not been provided. Reactions of azirines with other heterocumulenes such as thiobenzoyl isocyanate and... 

In the reaction of 3-(dialkylamino)-2//-azirines with isothiocyanates, a similar [2+2] cycloaddition across the C=N bond occurs however in this case the strained bicyclic adducts undergo further transformation to give carbodiimides 54 which are in equilibrium with the dipolar heterocycle 53. ... 

Alky]-5-imino-3-methy -A2-l,2,4-thiadiazoIines react exotherm ally at 0°C with dibenzoy] or dimethoxy carbonylacetylenes in tetrahydrofuran to give the 2-alkylaminothiazoles in high yields (1564). The cycio addition reaction of 2-pyridyl isothiocyanates with 1-azirines results in the formation of 2-pyridylaminothiazoles (1565). 

Triphenyl-4,7-dihydro-l,3,5-thiadiazepin-4-one was prepared in 1974 by the reaction of thiobenzoyl isocyanate with 2,3-diphenyl-l-azirine <74JOC3763>. The second examples of this ring system, 1,3,5-thiadiazepin-6-ones (112), were prepared by the reaction of the isothiocyanate derivatives (110) with methanol or isopropylthiol. The initially formed adducts (111) were readily converted into the final products (112) upon treatment with a base, such as sodiiun methoxide (Scheme 18) <86S817>. 

In the reaction of 3-(dialkylamino)-2//-azirines with trimethylsilyl isothiocyanate the initially formed [2+2] cycloadduct 59 again is transformed into the five-membered ring compound 60, which on treatment with methanol to remove the silyl group is converted into 4-(dialkylamino)imidazoline-2-thiones 61 (yield 26-80... 

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