Sulfonamide Bond Research Articles

Excited-State Proton Transfer in Hydroxynaphthaldehydes Covalently Bound to Proteins

The kinetics and equilibrium of excited-state proton transfer (ESPT) in 2-hydroxynaphthaldehyde-1 (HNA-2.1) bound to proteins (bovine serum albumin, cytochrome c, and lysozyme) by an alkylamino bond was studied by means of fluorimetric steady-state and time-resolved methods. The results were compared to analogous data for 1-hydroxy naphthaldehyde-4 (HNA-1.4) bound to proteins and for other 2-naphthol derivatives bound to proteins by a sulfonamide bond, Conclusions concerning the influence on ESPT of the mode of binding and of intramolecular hydrogen bonds occurring in the case of HNA-2. 1 were drawn. An intramolecular hydrogen bond enhances the rate of ESPT but the molecular environment in the protein leads to an opposite effect by increasing reorganization energy during proton transfer. The results obtained prove that the mode of binding and the kind of group linking fluorophores to proteins influence considerably the rate and mechanism of ESPT. In naphthol groups bound to proteins by an alkylamino bond, proton dissociation depends strongly on the molecular environment in the macromolecule. This is due to the short length of the alkylamino bridge and its small interaction with electronic orbitals of the aromatic system. Fluorophores bound to proteins by a sulfonamide bond show a higher rate of ESPT, which is due partly to the electron withdrawing effect of the linking arm. The efficiency of ESPT for naphthol groups bound to proteins by a sulfonamide bond is, in most cases, sufficient for acidification of the medium and influence of the proton gradient in biological membranes.

Synthesis of β-aminosulfonopeptides activated through selective N-nitration of a taurine amide unit

β-Sulfonopeptides bearing a taurine in place of a penultimate amino acid unit were designed and synthesized as inhibitors of D-alanyl-D-alanine transpeptidases; N-nitration of the sulfonamide bond in the presence of multiple carboxamide groups was selectively accomplished through use of NO 2BF 4.

Amide-Based Rotaxanes with Terephthal, Furan, Thiophene and Sulfonamide Subunits

The synthesis and characterization of new amide-based rotaxanes 6b-d containing terephthal, furan and thiophene subunits is described. Furthermore, the first rotaxanes ever obtained with sulfonamide bonds 6e, f are reported. These mechanically bonded compounds can be prepared in only few simple steps in nonstatistical high yields (up to 41%), which demonstrates that it is possible to significantly modify the structure of these species and of their components without disturbing the non-ionic template-effect responsible for the formation of their mechanical bonds.

Synthesis of 6,7,8,9‐tetrahydro‐N,N‐di‐n‐propyl‐1H‐benz[g] indol‐7‐amine, a potential dopamine receptor agonist

AbstractIn this work, the synthesis of 6,7,8,9‐tetrahydro‐N,N‐di ‐n‐propyl‐1H‐benz[g]indol‐7‐amine (1) is described. This compound was designed as an indole bioisostere to the known dopamine receptor agonist 5‐OH‐aminotetraline 2. The key step of the synthesis was a Mukaiyama type aldol condensation between the dimethyl acetal of 1‐(p‐toluenesulfonyl)pyrrole‐3‐acetaldehyde (4) and 4‐di‐n‐propylamino‐1‐trimethylsilyloxycyclohexene (8) followed by cycloaromatization to afford 1‐p‐toluenesulfonyl‐6,7,8,9‐tetrahydro‐N,N‐di‐n‐ propyl‐1H‐benz[g]indol‐7‐amine (10). Scission of the sulfonamide bond in 10 gave the target compound 1. A byproduct which was isolated was assigned to the structure of 1‐(p‐toluenesul‐fonyl)‐6‐[3‐[1‐(p‐toluenesulfonyl)]pyrrolyl]indole (11). This compound was also synthesized in good yield by an acid catalyzed dimerization of the dimethyl acetal of 1‐(p‐toluenesulfonyl)pyrrole‐3‐acetaldehyde (4). Preliminary screening of 1 indicated that it possesses central dopamine receptor agonist properties.

Mode of action, crop selectivity, and soil relations of the sulfonylurea herbicides

AbstractThe sulfonylurea herbicides are characterized by broad‐spectrum weed control at very low use rates (c. 2–75 g ha−1), good crop selectivity, and very low acute and chronic animal toxicity. This class of herbicides acts through inhibition of acetolactate synthase (EC 4.1.3.18; also known as acetohydroxyacid synthase), thereby blocking the biosynthesis of the branched‐chain amino acids valine, leucine and isoleucine. This inhibition leads to the rapid cessation of plant cell division and growth. Crop‐selective sulfonylurea herbicides have been commercialized for use in wheat, barley, rice, corn, soybeans and oilseed rape, with additional crop‐selective compounds in cotton, potatoes, and sugarbeet having been noted. Crop selectivity results from rapid metabolic inactivation of the herbicide in the tolerant crop. Under growth‐room conditions, metabolic half‐lives in tolerant crop plants range from 1–5 h, while sensitive plant species metabolize these herbicides much more slowly, with half‐lives > 20 h. Pathways by which sulfonylurea herbicides are inactivated among these plants include aryl and aliphatic hydroxylation followed by glucose conjugation, sulfonylurea bridge hydrolysis and sulfonamide bond cleavage, oxidative O‐demethylation and direct conjugation with (homo)glutathione. Sulfonylurea herbicides degrade in soil through a combination of bridge hydrolysis and microbial degradation. Hydrolysis is significantly faster under acidic (pH 5) than alkaline (pH 8) conditions, allowing the use of soil pH as a predictor of soil residual activity. Chemical and microbial processes combine to give typical field dissipation half‐lives of 1–6 weeks, depending on the soil type, location and compound. Very short residual sulfonylurea herbicides with enhanced susceptibility to hydrolysis (DPX‐L5300) and microbial degradation (thifensulfuron‐methyl) have been developed.

Photoeffects in thin film chromophore-quencher assemblies: variations in the light absorber

The abilities of a variety of inorganic and organic compounds to act as electron transfer quenchable light absorbers in thin polymeric films have been examined. The compounds, each of which contains a primary amine, were chemically bound in precast chlorosulfonated polystyrene films by sulfonamide bond formation. Visible photolysis of the films in the presence of an oxidative quencher and a reductive scavenger leads to a sustained photocurrent response from 14 of the 18 compounds studied. Differences in the photocurrent output as the chromophore is changed can be explained qualitatively based on a kinetic model whose key steps are optical excitation of the absorber followed by excited state electron transfer.

Amino acids and peptides. V. Synthesis of amino acid derivatives containing a sulfonamide bond.

Amino acid derivatives containing a sulfonamide bond were synthesized and their biological activities were examined. Some sulfonyllysine derivatives exhibited fibrinolytic activity. N4-Lysylsulfanilamide was also prepared and treated with trypsin. The results suggest that a drug acylated with an amino acid might have improved solubility in water and might act as a kind of prodrug.

Chemistry of Exciplex and Its Synthetic Applications. Synthesis of Oxindoles and Tetrahydroisoquinolones and Photocleavage of Sulfonamide Bonds

Chemistry of Exciplex and Its Synthetic Applications. Synthesis of Oxindoles and Tetrahydroisoquinolones and Photocleavage of Sulfonamide Bonds

Photolysis of dansyl amino acids and dansyl peptides

Dansyl amino acids and dansyl peptides have been shown to undergo ready photolysis. The major photolysis products identified from neutral or basic solution were dansylic acid, the corresponding amino acid or peptide, and ammonia. In acidic solutions, the yield of amino acid and/or peptide was good while that of ammonia was low or negligible. The highest quantum yields attained for cleavage of the sulfonamide bond were seen in acid. Dansyltryptophan and dansylated peptides containing tryptophan were cleaved at slower rates and generally with less specificity than other derivatives examined. The rate of photolysis at a given light flux was dependent on acid concentration; the process may be a hydrolysis of the derivative in an excited state.

Photolytic cleavage of sulfonamide bonds.

It has been found that the sulfonamide bond is relatively susceptible to photolytic cleavage. The breakdown was effected either by irradiation with a source having a continuous emission above the wavelengths of 1800 angstroms or by another source emitting principally at 2537 angstroms. Less destruction of the amino acids was seen with the latter relative to the sulfonamide bond cleavage. The cleavage was not effected by irradiation at wavelengths greater than about 3000 angstroms. Side reactions were noted involving decarboxylation, demination, and destruction of certain susceptible amino acids such as tryptophan. In only one case was a product found that arose from cleavage of a carboxamide bond; glycyltyrosine gave glycine and tyrosine upon irradiation. A yield of 75 percent of the corresponding amino acid has been obtained by irradiation of tosylhistidine; yields of 75 to 100 percent have been obtained from sulfamic acid (NH(2)SO(3)H). A qualitative method for identifying sulfonylated amino acids is described.

Protein conformation in solution: cross-linking of lysozyme.

The cross-linking of lysozyme by reaction with phenol-2,4-disulfonyl chloride has been effected. The cross-linked protein retained enzymatic activity, has approximately the same molecular weight as native lysozyme, and has essentially the same conformation as native lysozyme as judged by optical rotatory dispersion analysis. The positions of sulfonylation were assigned by a standard degradation sequence; the presence of sulfonamide bonds was confirmed by infrared spectroscopy. Cross-links may thus be introduced without incurring major structural changes in the protein, and certain intramolecular distances that are allowed in the active enzyme may be deduced.