Benzenesulfonamides, reduction

Benzenesulfonamide, Ar,AT-dibromo-4-methyl-(TsNBr2) bromohydrination with, 287 Benzenesulfonamides reductive cleavage, 247 synthesis of drugs, 301, 307-308 Benzenesulfonic acids. See Sulfonic acids Benzenesulfonic acid, 4-methyl-, esters (tosylates) alkyl a-synthons, 16, 24, 47, 93 fragmentation of, 89 rearrangement of, 32 reductive cleavage of, 114, 202-203 —, 4-methyl-, hydrazide (tosylhydrazine) hydrazones of fragmentation, 89 reduction, 109... 

Borohydride reduction of 3-aryl-l,2-benzisothiazole 1,1-dioxides gives the 2,3-dihydro compounds 73JMC1170). Reduction of either 2-methylsaccharin or 2-hydroxymethylsac-charin with lithium aluminum hydride gives the same product, iV-methyl-o-hydroxymethyl-benzenesulfonamide (73AHC(15)233). 

The reaction of nitro compound 337 with /-butyloxycarbonic anhydride in the presence of DMAP resulted in 2-nitro-benzenesulfonamide 338, which upon reduction with iron in AcOH gave 339 (Scheme 70). The latter when refluxed with 2,5-dimethoxytetrahydrofuran in AcOH afforded pyrrole sulfonamide 340 in good yield along with the fused 1,2,5-thiadiazepines 103 and 104, as a side product. Subsequently, 340 upon reaction with triphosgene afforded 103 and 104. 

The ability of mammalian tissue to reduce azo bonds is rather poor. With p-[2,4-(diaminophenyl)azo]benzenesulfonamide (Prontosil), in vivo reduction forms sulfanilamide. However, pretreatment with antibiotics destroys the intestinal bacteria, which results in a decrease in the formation of the amino compound. Generally, it would appear that both nitro and azo reduction as a function of specific tissues is of minor importance, and intracellular bacteria as well as intestinal bacteria are actually responsible for these reductions. 

The addition of A,V-dibromobenzencsulfonamidc to hexose-derived glycals afforded, after reduction of the N —Br bond of the initial adducts, a mixture of diastereomeric 2-bromo-l-phenylsulfonylamino derivatives913 b. In the case of tri-O-benzyl-D-glucal the diastereoselectiv-ity in favor of the diaxial adduct 7 was improved by the alternative procedure using iodonium di-.cyw-collidine perchlorate and benzenesulfonamide (see Section 7.2.6.1.4.). 

L.-M. Yang and co-workers designed and synthesized a new series of frans-stilbene benzenesulfonamide derivatives as potential antitumor agents.A common precursor diethylphosphonate was prepared from commercially available sulfanilamide in six steps. The aromatic nitrile-to-aldehyde reduction was affected by the modified Stephen reduction using Raney nickel alloy in aqueous formic acid. The corresponding aldehyde was obtained in high yield. 

Li, NH3, 75% yield or Na, NHs. Note that in the following example enone reduction is slower than benzenesulfonamide cleavage. ... 

SmL, DMPU, 50-97% yield. The reaction works well for alkyl-substituted aziridines benzenesulfonamides react faster than tosyl amides. Primary toluenesulfonamides do not give clean reductive cleavage, but benzenesulfonamides do. 

CDAA (N-N-diallyl-2-chloroacetamide) was reported to reduce mitosis in barley (Hordeum vulgare L.) roots nearly 90% after 96 h at 57 yM (38). Propachlor (2-chloro-N-isopropylacetanilide) totally inhibited mitosis in onion (Allium cepa L.) root tips after an 18 h treatment with 75 yM (3 ). At 20 yM cell division was reduced approximately 50% and cell enlargement was reduced 40% in oat coleoptiles (39). After 24 h, 100 yM ioxynil (4-hydroxy-3,5-diiodobenzonitrile) reduced the mitotic index in broad bean (Vicia faba L. ) and pea root tips ( ). Few herbicides that inhibit cell division have been studied in adequate detail to locate the site of the block. A notable exception is the herbicide chlorsulfuron (DPX 4189, 2-chloro-N- [(4-methoxy-6-methyl-l,3,5-triazin-2-yl)amino]carbonyl -benzenesulfonamide) ( ). Ray reported a 50% reduction in corn growth 3 h after treatment with 28 yM chlorsulfuron. Mitosis in broad bean root tips was significantly reduced by 2.8 yM, whereas in three different tests, cell enlargement was not influenced with concentrations of 28 yM. Thymidine incorporation into DNA was inhibited in corn root tips after a 1 h treatment with... 

Celecoxib (CEL), 4-[5-(4-methylphenyl)-3-(trifluoromethyl)-lH-pyrazol-l-yl]benzenesulfonamide, used for the relief from symptoms of ankylosing spondylitis, a chronic inflammatory disease of the axial skeleton, has been determined elecSrochemically by a PANI grafted NH2-MWCNT electrode [53]. Aniline was electrochemically polymerized in presence of NH2-MWCNTS on an indium tin oxide (ITO) electrode. The composite film had a lai e surface area and showed a stripping DPV signal from CEL reduction after an accumulation time of only 30 s at -0.5 V. With stripping SWV, ten times higher peak currents were detected. 

The other method for preparation of a derivative may be utilized for both aliphatic and aromatic nitro compounds. This involves the reduction of the nitro compound to the corresponding primary amine (Eq. 25.61), followed by conversion of the amine to a benzamide or benzenesulfonamide, as described in Section 25.14. The reduction is most often carried out with tin and hydrochloric acid. 

As seen in previous examples, the intermediate iminium salt produced by reductive amination need not be isolated, and reduction in situ is very common.52 A mixture of sodium cyanoborohydiide and ammonium acetate was used for the reductive amination of the aldehyde derived from acid hydrolysis of the dioxolane moiety in 1,94. In this example, the dioxolane moiety was hydrolyzed to release the aldehyde, which reacted with NaBH3CN/NH40Ac to produce an amine. The amine was then protected as its benzenesulfonate. The final product was methyl 9-amino-nonanoate benzenesulfonamide, 1.95 (20% overall yield).53... 

---