Sulfonyl carbamates

Cottrell and Hey wood (1965) were the first to describe the herbicidal action of benzene sulfonyl carbamates. The most active member of this group is asulam, methyl 4-aminophenylsulfonyl carbamate (12). 

Asulam is readily soluble in polar solvents and slightly soluble in water (5 g/1). Its alkali and alkaline earth metal salts are readily soluble in water. The sulfonyl and ester groups enhance the acidity of the imino group so that it forms stable water-soluble salts with alkali hydrogen carbonates. Thus it is formulated as an aqueous solution of the sodium salt (400 g asulam per litre). 

Asulam is prepared from 4-aminobenzenesulfonamide and methyl chloroformate in the presence of an acid-binding agent. The amino group must be protected before the reaction. Reaction scheme  

Asulam is used pre- and postemergence as a selective herbicide. In plants it is translocated mainly basipetally with the nutrient stream. Absorption through the leaves can be considerably increased with surfactants. 

It is important in its action against deep-rooted grass weeds in the foat that asulam is only slightly adsorbed by the soil colloids and, because of its high water solubility is easily leached into the deeper layers of the soil. 

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Support-bound /V-sulfonyl carbamates, which can be prepared by N-sulfonylation of resin-bound carbamates, are susceptible to nucleophilic cleavage. These intermediates enable the solid-phase preparation of A-ary I- or /V-alkylsulfonamides using inexpensive hydroxymethyl polystyrene (Entries 8 and 9, Table 3.15). Polystyrene-bound carbamates can also be cleaved by treatment with acyl halides in the presence of Lewis acids (Entry 4, Table 3.16). 

Bromocyclization of the thiocarbamidate generated from f-butylisothiocyanate and 3-buten-2-ol gave oxazolidinone products with slight selectivity for the cis isomer (cis.trans 1.9 1),2271 while iodocycliza-tions of /V-sulfonylated carbamates gave somewhat higher stereoselectivity (equation 117).233... 

Using / -nitrobenzene sulfonyl carbamates as the source of nitrene, the reaction needs to be activated either by a carbonate in the presence of phase-transfer reagent or by sonication. Yields are only moderate and this reaction cannot be regarded as being preparatively useful.101,102... 

Figure 2. Gas chromatogram of the N-HFB Orpropyl derivatives of the hydrolysate of trypsin CVB hydrogel sulfonyl carbamate (3f). Conditions 12 ft. X 1/4 in. glass column packed with 3% OV-1 on Chromasorb-W initial temp was 100° ford min, programed to 250° at 4°/min.

Figure 4. Active site titration recorder trace of 17.0 mg trypsin CVB hydrogel sulfonyl carbamate (If) being titrated by 19.75 mL of 0.12 mM NPGB in pH 8.3 veronal buffer burst, 0.060 A.

The typical ring-opening reaction with alcohols, either neat,66 or in the presence of bases such as sodium alkoxide51 or triethylamine,50 leads to the corresponding iV-[(2-sulfanylphenyl)-sulfonyl]carbamates 1. 

Synonyms methyl[(4-aminophenyl)sulfonyl] carbamate Asilan Asulox... 

N-acyl sulfamic acid esters (or Thioester), n-acyl sulfonamides, and N-sulfonyl carbamic acid esters (or thioesters)... 

Synonyms 4-Aminobenzenesulfonyl methyl carbamate Methyl N-(4-aminobenzenesulfonyl) carbamate Methyl ((4-aminophenyl) sulfonyl) carbamate Methyl sulfanilyl carbamate Sulfanilylcarbamic acid, methyl ester Empiricai C8H10N2O4S Properties Colorless cryst. sol. in chlorinated hydrocarbons, petroi. oiis, many hydroxylic soivs. mod. sol. in water m.w. 230.26 m.p. 143-144 C Toxicoiogy LD50 (oral, rat) 2 g/kg, (oral, mouse) > 5 g/kg mod. toxic by ing. 

Synonyms Asilan Asulfox F Asulox Asulox 40 Jonnix MB 9057 Methyl A-(4-aminobenzenesulfonyl)carbamate Methyl((4-aminophenyl)sulfonyl)carbamate Methyl sulfanilylcarbamate. 

S-((5-Methoxy-2-oxo-l,3,4-thiadiazol-3(2//)-yl)methyl) 0,0-dimethyl phosphorodithioate, see Methidathion Methoxypropazine, see Prometon Methyl aldehyde, see Formaldehyde Methyl A/ -(4-aminobenzenesulfonyl)caibamate, see Asulam A -(((Methylamino)caiboityl)oxy)ethanimidothioate, see Methomyl A -(((Methylamino)caibonyl)oxy)ethanimidothioic acid methyl ester, see Methon l Methyl((4-aminophenyl)sulfonyl)carbamate, see Asulam Methylazinphos, see Azinphos-methyl... 

The related AABoc compound, tert-hutyl 7V (/>-toluene-sulfonyl) carbamate, is also used for the synthesis of protected secondary amines in a similar marmer. In this case, hoth of the amine protecting groups can be selectively removed (eq 3). The tosyl group is deprotected selectively hy sodium naphthalenide to give the (V Boc amino compound. Alternatively, selective depro-... 

Fot the use of SESCl in the synthesis of f-butyl [[2-(trimethylsilyl) ethyl]sulfonyl]carbamate, a useftil reagent in Mitsunobu reactions, see JV-(t-butoxycarbonyl)- >-toluenesulfonamide Campbell, J. A. Hart, D. J., J. Org. Chem. 1993,58, 2900. 

A mixture of p-toluenesulfonamide and tetraethyl orthocarbonate heated with stirring whereupon alcohol distils at 120-160° during 2 hrs. (after which a 67% yield of the intermediate diethyl N-(p-toluenesulfonyl)imidocarbonate can be isolated), the temp, allowed to reach finally 200-205° ->> ethyl ethyl-(p-toluene-sulfonyl) carbamate. Y 92%. R. F. Meyer, J. Org. Ghem. 28, 2902 (1963). 

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