Sulphamic acids synthesis

A convenient synthesis of the triethylamine-sulphur trioxide complex Et3NS03 (129) has been reported by Nair and Bernstein177. A 75% yield of 129 was obtained by the reaction of triethylamine with chlorosulphonic acid. Reaction of quinuclidine N-oxide with SO2 yield a stable colourless, non-hygroscopic material which was identified by X-ray and elemental analysis to be the quinuclidine-sulphur trioxide complex 130178. The complex was exceedingly stable and its hydrolysis in water even at 86 °C was very slow, 280 times slower than the analogous rate for triethylamine-sulphur trioxide (129). A single X-ray structure determination of the complex showed a sulphamic acid type coordination of SO3 to the quinuclidine nucleus [N-S =1.831 (6) A]. 

The synthesis of esters of sulphamic acids is generally achieved by the reaction of the corresponding sulphamoyl halides with an alkoxide or alcohol according to equation 20. A large variety of such esters have been prepared and the synthetic procedures and their properties have been reviewed1. The present work describes the synthetic procedures which have been developed since 1980 to incorporate the sulphamoyl ester moiety (NS03R) into molecules and to look at the general reactivity of sulphamate esters. 

Unsubstituted sulphamide NH2S02NH2 has recently been reported to be useful in functional group synthesis. Reaction of sulphamide with acid chlorides leads to a one-pot synthesis of nitriles 402378 (equation 132). The reaction is successful for a large variety of aliphatic and aromatic acid chlorides with electron-withdrawing and electron-donating substituents. Sterically hindered as well as heterocyclic nitriles are also obtained in high yields. The reaction is considered to proceed via the iV-acylsulphamide, which is further enolized and cleaved to yield the nitrile 402 and sulphamic acid. 

Ozyilmaz, A.T., Ozyilmaz, G., and Yigitoglu, O. (2010) Synthesis and characterization of poly(aniline) and poly (o-anisidine) films in sulphamic acid solution and their anticorrosion properties. Prog. Org. Coat., 67, 28-37. 

R. S. Rao, K. Nagaiah, A. R. Prasad, Cat. Commun. 2006, 7, 797-801. Sulphamic acid an efficient, cost-effective and recyclable solid acid catalyst for three-component synthesis of homoaUyhc amines. Zirconyl chloride (ZiOClj) (d) B. Das, B. Ravikanth, K. R. Reddy, B. V. Rao, Helv. Chim. Acta 2007, 90, 105-109. Zirconyl chloride (=dichlorooxozir-conium) as an efficient catalyst for one-pot multicomponent synthesis of homoallylic amines. Sohd-supported perchloric acid (HClO -SiOj) (e) L. Nagarapu, V. Paparaju, G. Pathuri,... 

The phase transfer catalysis process has also been extended to synthesize the alkyl and aryl esters (170) of N-aryl sulphamic acids212 (equation 23). If the ratio of aliphatic alcohol (169) to sulphamoyl chloride (168) is increased from 1 1 to 2 1, then N-alkyl-iV-arylsulphamate esters (171) with similar alkyl groups are obtained together with considerable amounts of iV-arylsulphamic acid esters (170). The exclusive formation of the iV-alkyl-iV-arylsulphamate esters (171) can be achieved by employing longer reaction times. A second approach to the synthesis of 171 would be to react the iV-methyl-iV-phenyl sulphamoyl chloride (172) with the alcohol. This was attempted, but the ester failed to form even under forcing conditions. The corresponding AT-alkyl iV-arylsulphamate ion (173) was isolated (equation 24) hydrolysis to the acid was considered to occur as opposed to nucleophilic displacement of the chloride by the methanol. 

A facile stereospecific synthesis of 3-amino-2-oxoazetidine-l-sulphonic acids (67) has been achieved by the cyclization of acyl sulphamates (derived from P-hydroxyamino-acids) under basic conditions. Barrett and Quayle have shown... 

---