Benzylsulfonyl chloride

E)-l-Trimethylsilyl-l-alkenes.1 These alkenes can be prepared by reaction of the lithium anion (1) of trimethylsilyldiazomethane with primary alkyl halides followed by decomposition with CuCl (86-96% yield). (E)-2-Aryl-l-trimethylsi-lylethylenes are obtained directly by reaction of trimethylsilyldiazomethane with benzylsulfonyl chlorides and triethylamine. 

Benzylsulfonyl chloride is prepared in similar manner by the following procedure. A mixture of 76 g. (1.0 mole) of thiourea, 126 g. (1.17 mole) of benzyl alcohol, and 150 ml. of ethanol is refluxed for 30 minutes, the initial exothermic reaction being controlled by external cooling. After the addition of 1 1. of water the mixture is chlorinated as described above. The solid product (155 g.) is removed several times during the chlorination, and the combined product is recrystallized from benzene to give benzylsulfonyl chloride, m.p. 91-92°. 

The reaction of aromatic nitrile oxides with methanesulfonyl and benzylsulfonyl chloride in the presence of triethylamine yields the sulfonate esters of hydroxamoyl chlorides XII ( ). 

Resin 23 was first swollen in CH2CI2 and, in a manner that parallels the route employed in the solution-phase synthesis, was reacted with a selected benzylsulfonyl chloride and t-BuOLi as a base to afford the corresponding sulfonamide resin 28, containing the first diversity element R. The sulfonamide resin 28 was then reacted under Mitsunobu conditions (PPha (triphenyl phosphine), DIAD (diisopropyl azodicarboxylate), THE, room temperature) with the appropriate alcohols. This process efficiently produced resin 29 and introduced the second diversity element R. Cyclization reaction of resin 29 was promoted by sodium hydride in DMF and led to the formation of the desired thiazolo[4,5-c] [l,2]thiazine resin 30. Treatment of resin 30 with mCPBA in CH2CI2 generated the resin-bound cyclic sulfonamide 31. Finally, the thiazolo[4,5-c][l,2]thiazine derivatives 5 were formed and cleaved from the resin (in a traceless manner" ) by treatment of resin 31 with the corresponding amines (R R" N diversity elements) in respectable yields (34 examples, from 11% to 29% for seven linear steps starting with Merrifield resin 1, Table 10.4). 

This is an elimination-addition (E-A) pathway involving a transient, highly reactive, sulfene intermediate. " An illustrative example is provided by the reaction of benzylsulfonyl chloride 9 with isopropanol in the presence of a base, triethylamine, to yield the isopropyl sulfonate 10 (Equation 11). 

In the nucleophilic substitution reactions of alkylsulfonyl chlorides and ring-substituted benzylsulfonyl chlorides, the operation of two competing reaction pathways has been established (a) E-A (sulfene) mechanism and (b) direct nucleophilic substitution at sulfur (general base catalysis). The relative significance of these competing mechanisms depends on the nature of the substrate and the precise reaction conditions. In the hydrolysis of cyclopropane-sulfonyl chloride 11 with tertiary amines in organic media, the sulfene 12 appears to be the crucial intermediate in the formation of cyclopropanesulfonic acid 13 (Equation 12). ... 

Cerfontain and co-workers suggested that the last step of the reaction, namely proton removal from the complex, was not rate-contributory, but this argument may not be valid since a more recent publication reported a higher value of the kinetic isotope effect (kn kxi) of 1.9-2.5. In sulfonylation using alkylsulfonyl chlorides, there is competing alkylation the latter is enhanced by increasing stability of the alkyl cation. Thus reaction of isopropyl, tertiary butyl and benzylsulfonyl chlorides caused facile alkylation of aromatic substrates in the presence of aluminium chloride in nitromethane at 25 °C. ... 

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