- LDA-promoted decomposition of benzenesulfenamides. A route to aminyl radicals by dioxygen oxidation of lithium amides
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The LDA-promoted decomposition of N-monosubstituted sulfenamides 1a-d occurs through the formation of thioaminyl anions, which undergo oxidation either at sulfur, with formation of sulfonamides, or at nitrogen, with formation of thioaminyl radicals, depending on the nature of the 4'-substituent. The reaction of N,N-disubstituted sulfenamides 1e-h proceeds through the intermediacy of a lithium complex capable of generating aminyl radicals via sulfenyl group transfer to the di-iso-propylamido anion and subsequent aerial oxidation of the resulting lithium amides 3e-h.
- Barbieri, Anna,Montevecchi, Pier Carlo,Nanni, Daniele,Navacchia, Maria Luisa
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p. 13255 - 13264
(2007/10/03)
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- SULFENAMIDES AND SULFINAMIDES VIII. THE CHROMATOGRAPHY OF ARYL SULFENAMIDES
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Substituent effects with respect to position and extent of substitution in a series of N-aryl benzenesulfenamides (ArSNHAr') have been examined over several chromatographic systems.In normal phase TLC, although methyl substitution in either ring leads to
- Chan, Christopher,Cole, Edward R.,Southwell-Keely, Peter T.
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- SULFENAMIDES AND SULFINAMIDES III. CONJUGATIVE AFFINITY AND pKa VALUES OF ARYL SULFENAMIDES
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Relationships are discussed between the pKa values determined spectroscopically in aqueous media and the conjugative affinity of the sulfur atom in transmitting substituent effects in a series of aryl sulfenamides. - Key words: Sulfenamides; pKa values; c
- Bayfield, Raymond F.,Cole, Edward R.
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p. 237 - 242
(2007/10/02)
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- Alkyl- and Arylsulfenanilides by Cycloelimination of Propene from N-Aryl-S-isopropyl-sulfimides
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A series of N-aryl-S-isopropyl-S-alkyl- or aryl-sulfimides has been prepared and transformed into alkyl- or arylsulfenanilides, respectively, by thermal cycloelimination of propene. - Keywords: Sulfimides; Sulfenanilides; Thermolysis; Cycloelimination.
- Claus, Peter K.,Silbernagel, Waltraud,Franek, Walter,Rieder, Werner
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p. 841 - 850
(2007/10/02)
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- Acid-promoted Decomposition of Benzenesulphenanilides and N-Aryl Bis(benzenesulphen)amides
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The decomposition of 4'-substituted benzenesulphanilides (1a-d) in the presence of trifluoroacetic acid (0.6 equiv.) leads to N-arylbis(benzenesulphen)amides (6a-d) in variable yields, depending on the 4'-substituent, in addition to disulphide (4) and anilines (3a-d), whereas products arising from sulphenylation of the N-aryl ring result from 3'-methoxybenzenesulphenanilide (1g).The 4'-nitro- and 3'-nitro-benzenesulphenanilides (1e,f) react with a slight excess of trifluoroacetic acid to give only (4), the thiosulphonate (5), and aniline (3e,f).The findings are interpreted in terms of possible nucleophilic attack at the S-N bond of a protonated sulphenanilide by the nitrogen or the N-aryl ring of another sulphenanilide unit, according to the nature of the substituent and its position, with displacement of aniline (3).The reaction of (1a-d) with 1.5 equiv. of trifluoroacetic acid leads to complete disappearance of the initially formed amides (6a-d) with concomitant formation of phenazines (9) and/or p-quinone di-imines (8).Similar results are obtained by using boron trifluoride-diethyl ether.Di-imines (8) and phenazines (9) are explained on the basis of a mechanism initially involving nucleophilic attack by (1) and/or (6) and/or (3) at the ortho and para positions of an intermediate cation, possibly (18A) or (18B), and loss of the disulphide (4).
- Benati, Luisa,Montevecchi, P. Carlo,Spagnolo, Piero
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p. 2261 - 2266
(2007/10/02)
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