Arylsulfonyl isocyanates

Oligomers of phosgene, such as diphosgene [503-38-8] (COCl2)2, have found use in the laboratory preparation of isocyanates. Carbamoyl chlorides, A[,A/-disubstituted ureas, dimethyl- and diphenylcarbonates, and arylsulfonyl isocyanates have also been used to convert amines into urea intermediates, which are subsequendy pyroly2ed to yield isocyanates. These methods have found appHcations for preparation of low boiling point aUphatic isocyanates (2,9,17). 

Both chlorsulfuron and sulfometuron methyl can be prepared by the reaction of the appropriate arylsulfonyl isocyanate and the substituted heterocyclic amine as shown in Fig. 2. 

In contrast to the acylation with carboxylic acid chlorides, secondary 1,1-enediamines react with isocyanates and isothiocyanates to give cleanly the /7-carbon acylated products. Carbamoyl-substituted enediamines (175) have been obtained from 174 and arylsulfonyl isocyanates (equation 67)140,141. 

Arylsulfonyl isocyanates (e.g. R = Ph, Me-4-CgH, F-4-CgH or Cl-4-CgH ) have been prepared under milder conditions, however, by addition of catalytic quantities of an Isocyanate to the corresponding sulfonamide/phosgene mixture [2087a]. 

While alkyl and aryl isocyanates are only converted to carbonimidoyl dichlorides by phosphorus pentachloride, arylsulfonyl isocyanates can be directly chlorinated to produce arylsulfonylcarbonimidoyl dichlorides. For example, chlorination of benzenesulfonyl isocyanate at 60 C yields benzene-sulfonylcarbonimidoyl dichloride (XXIX) in unspecified yield ( ). 

Arylsulfonyl isocyanates were formed via the carbonylation of selenilimines and (arylsulfonyliminoiodo)benzenes (eqs 6 and T)P... 

Alkyl azides readily undergo 1,3-dipolar cycloaddition to arylsulfonyl isothiocyanates (375) to yield thiatriazolines (376). Thermolysis of (376) in the presence of isocyanates or carbodiimides produces 1,2,4-thiadiazole derivatives (378) and (379), respectively. The intermediate formation of a thiaziridinimine (377) has been postulated as indicated in Scheme 137 (75JOC1728, 75S52). The use of isothiocyanates as dipolarophiles produces dithiazolidines (380) instead of the thiadiazole derivatives. In these reactions the intermediate thiazirine (377) functions as a 1,3-dipole with the positive charge primarily localized on sulfur. It was recently proposed that the reaction of oxaziridines (381) with isothiocyanates produces a similar thiazirine intermediate (382) which reacts in a different regiospecific manner with isothiocyanates to produce 1,2,4-thiadiazole derivatives (383) and (384 Scheme 138) (74JOC957). 

N-l and 0. Other acylating agents used have been arylsulfonyl chlorides1199 and alkylchloroformates.61 Isocyanates react with N-l of 2-pyrazolin-5-ones having no 1-substituent to form 5-oxo-2-pyrazolin-1-carboxanilides. Treatment of l-acyl-5-acyloxypyrazoles with piperidine in ethanol removes the 0-acyl to give l-acyl-2-pyrazolin-5-ones.1898... 

Alkylenebis(3-arylsulfonyl ureas) react readily with phosgene in a similar way to produce the corresponding sulfonyl isocyanate and diisocyanate [2087a] ... 

Preparation of Hydrogel Arylsulfonyl Carbamates. To a solution of hydrogel (1-4.0 g) in dry pyridine (20-40 mL) was added eitherp-toluenesulfonyl Isocyanate (pTSI), 3.0 g, or p-nitro-benzenesulfonyl Isocyanate (p-NBSI), 0.5-3.0 g and the mixture was heated at 70 under nitrogen for 4 hr. The adduct was isolated by precipitation in benzene or ethanol. Repreclpltatlon from acetone or DMF yielded the desired products, IR (film) 3170 cm (-NH), 1530 cm" (-NO2), 1340, 1180 cm" (-SOj). The precise degree of substitution was determined by non-aqueous titration (Table II). 

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