Electrophilic Addition and Substitution Reactions of Bis((trifluoromethyl)sulfonyl)amide and Its N-Chloro Derivative

Abstract

Lithium bis((trifluoromethyl)sulfonyl)amide (1) reacts with S2O6F2 to form FSO2ON(SO2CF3)2 (2). Reaction of 2 with KF results in the cleavage of the S-N bond with the concomitant formation of CF3SO2F. The ease of electrophilic addition reactions of HN(SO2CF3)2 (3) with CH2=CHF, CH2=CF2, and CHF=CF2 depends upon the hydrogen content of the olefin. Addition occurs in a unidirectional fashion according to Markovnikov's rule to form CH3CHFN(SO2CF3)2 (4), CH3CF2N(SO2CF3)2 (5), and CH2FCF2N(SO2CF3)2 (6), respectively. Cleavage of the CF3-N bond in 5 by reaction with CsF leads to the formation of CH3CF3 in about 12% yield. The major product formed is CF3SO2F. The reactivity of fluorine atoms of the difluoromethylene group of 5 is shown by its reaction with (CH3)3SiN(CH3)2 in the presence of CsF under mild conditions where CF3SO2F, (CH3)3SiF, and CH3C[N(CH3)2]=NSO2CF3 (7) are formed. AgN(SO2CF3)2 is formed by the reaction of Ag2CO3 with an aqueous solution of 3 and undergoes metathetical reactions readily with compounds containing active halogen atoms to introduce the N(SO2CF3)2 group. Strong Lewis acids such as ZN(SO2CF3)2 [Z = R3Sn, R = CH3 (8), n-C4H9 (9), and C6H5 (10); Z = (CH3)3Si (11)] can thus be conveniently prepared. The vinyltin(IV) compound (CH3)3-SnCF=CF2 (12) is synthesized by the reaction between (CH3)3SnCl and CF2=CFBr in hexaethylphosphorus triamide and benzonitrile. Multinuclear NMR studies of the trialkylstannyl/silyl derivatives suggest a quasitetrahedral structure around the central silicon or tin atom as reflected by their very low 29Si (55.9 ppm) and 119Sn (∼250 ppm) NMR chemical shifts and 1J(119Sn-13C) and 2J(119-1H) coupling constants. Compounds 8, 9, and 11 can also be isolated by reaction of ClN(SO2CF3)2 (13) with the respective alkylmetal chlorides in a noncoordinating solvent. However, 13 fails to add across the perfluorovinyl group in CF2=CFSn(CH3)3 (12) and forms CF2=CFCl and 8 instead. Reactions of 13 with a variety of per/polyfluoroolefins, such as CF2=CFX [X = H, F, CF2CF2CF2CF2N- and CF2CF2OCF2CF2N-], CH2=CXY [X = H ; Y = F, CF3; X = Y = F] result in uni- or bidirectional addition to give 14-23. Insertion of ClCN into the N-Cl bond of 13 results in the formation of an azaalkene, CCl2=NN(SO2CF3)2 (24). Reaction of CFCl2S(O)Cl with 13 forms CFCl2S(O)N(SO2CF3)2 (25) with concomitant evolution of chlorine. © 1994, American Chemical Society. All rights reserved.