Ethanesulfonamide

An improved synthesis of 3,4-dihydro-2,l-benzothiazine 2,2-dioxide was reported by Togo and co-workers using photochemical conditions . Treatment of A-alkyl 2-(aryl)ethanesulfonamides 18 with (diacetoxyiodo)arenes under irradiation with a tungsten lamp at 20-30 °C afforded 2,1-benzothiazines 19 and 20. Chemical yields and selectivities were dependent upon the choice of solvents and the reactant s substituents 18 (Table 1). When THF and EtOH were used as solvents, the reactions failed to give the cyclized products, since their a-hydrogen was abstracted by the intermediate sulfonamidyl radical. Compound 20 was obtained as a major product when 1,2-dichloroethane was employed as a solvent. In contrast, in the case of EtOAc as solvent, compound 19 was obtained as the major product. 

In 2003, Togo and co-workers described a radical cyclization and ionic cyclization onto the aromatic rings of 2-(aryl)ethanesulfonamides 21 to produce 3,4-dihydro-2,l-benzothiazine 2,2-dioxides with polymer-supported hypervalent iodine reagents in good yields <03ARK11>. 

Chemical Name lH-Indole-5-ethanesulfonamide, N-methyl-3-(l-methyl-4-piperidinyl)-... 

Irradiation of the / -(aryl)ethanesulfonamides 190 in the presence of DAIB-I2 provides access to the dihydrobenzothiazine dioxides 191 and 192 (Scheme 55) (OOJOC926). In these reactions, formation of the thiazine ring by the radical cyclization pathway to give 191 is followed by electrophilic iodination of the arene nucleus to give 192. 

Amino sugars. Glycals undergo addition with the iodonium perchlorate and 2-(trimethylsilyl)ethanesulfonamide to afford 2-iodo-l-sulfonamide adducts which are transformed into the protected aminoglycosides on alcoholysis. 

Intramolecular cycloaddition leads to the formation of 2-azabicyclo [4.3.0] nonane 207 (equation 106). When AT-sulfmyl-2-(trimethylsilyl)ethanesulfonamide (208) is used in the imine Diels-Alder reaction, the 2-(trimethylsilyl)ethanesulfonyl group of 210 can be readily removed by cesium fluoride in DMF (equation 107). 

Trimethylsilyl)ethanesulfonamides are usually prepared by reaction of the amine with 2-(trimethylsilyl)ethanesulfonyl chloride in the presence of a suitable base. An improved large scale preparation of this reagent has been published in Organic Syntheses [Scheme 8.142]. In the first step sodium bisulfite is added to trimethylvinylsilane in the presence of the catalytic amount of ten-butyl perbenzoate. The resulting crude sodium sulfonate is then treated with... 

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