- Axinellamines as broad-spectrum antibacterial agents: Scalable synthesis and biology
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Antibiotic-resistant bacteria present an ongoing challenge to both chemists and biologists as they seek novel compounds and modes of action to out-maneuver continually evolving resistance pathways, especially against Gram-negative strains. The dimeric pyrrole-imidazole alkaloids represent a unique marine natural product class with diverse primary biological activity and chemical architecture. This full account traces the strategy used to develop a second-generation route to key spirocycle 9, culminating in a practical synthesis of the axinellamines and enabling their discovery as broad-spectrum antibacterial agents, with promising activity against both Gram-positive and Gram-negative bacteria. While their detailed mode of antibacterial action remains unclear, the axinellamines appear to cause secondary membrane destabilization and impart an aberrant cellular morphology consistent with the inhibition of normal septum formation. This study serves as a rare example of a natural product initially reported to be devoid of biological activity surfacing as an active antibacterial agent with an intriguing mode of action.
- Rodriguez, Rodrigo A.,Barrios Steed, Danielle,Kawamata, Yu,Su, Shun,Smith, Peter A.,Steed, Tyler C.,Romesberg, Floyd E.,Baran, Phil S.
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supporting information
p. 15403 - 15413
(2015/01/09)
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- Mechanistic studies on the chlorination of phenols with N-chlorobenzene sulphonamide
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The effects of substituents on the kinetics and reaction mechanism of chlorination of twenty three meta-, para- and ortho-substituted phenols by N-chlofobenzenesulphonamide (CAB) are reported. The variable order dependence on the substrate concentration for the substituents can be described by the rate equation, -d[CAB]/dt = k′[Ph] [CAB] [H+] + k″ [H 2O] [CAB] [H+]2. The reaction is acid catalysed and its dependence on H0 function suggests the presence of water molecule as a nucleophile in the rate-limiting step. The concave Hammett plot shows a transition in the rate-limiting step with varying nature of the substituents. The linear relation in the Exner plot suggests the operation of a similar mechanism in all the substituted phenols.
- Meenakshisundaram,Selvaraju
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p. 608 - 615
(2007/10/03)
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- Kinetics and mechanism of the reaction of α-phenoxypropanoic acids with sodium salt of N-chlorobenzene-sulphonamide: EDTA catalysis
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EDTA smoothly catalyses the oxidation cum chlorination of some 17 α-phenoxypropanoic acids with sodium salt of N-chlorobenzenesulphonamide in acidic solution. A ternary intermediate can be envisaged for describing the enhanced reactivity. Imperfections are observed in the linear Hammett relationship in the case of-NO2 substituents, irrespective of the position. The susceptibility constant, p(≈ + 1) indicates the development of an electron-rich transition state.
- Meenakshisundaram, Subbiah,Selvaraju
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- Reaction of N,N-dichloroarenesulfonamides with propargyl alcohol
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The reaction of N,N-dichloroarenesulfonamides with propargyl alcohol gives 3-hydroxy-2,2-dichloro-1,1-di(N-arenesulfonamido)propanes and N-(3-hydroxy-2,2-dichloropropylidene)arenesulfonamides. The latter were obtained due to the transformation of intermediate products, N-chloro-N-(3-hydroxy-2-chloro1-propenyl)arenesulfonamides, by the 1,3-migration of the halogen atom. The addition of arenesulfonamides formed in the reaction to N-(3-hydroxy-2,2-dichloropropylidene)arenesulfonamides results in the formation of 3-hydroxy-2,2-dichloro-1,1-di(N-arenesulfonamido)propanes.
- Drozdova,Kozyreva,Mirskova
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p. 243 - 245
(2007/10/03)
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- REACTION OF N,N-DICHLOROBENZENESULFONAMIDE WITH 3-CHLORO-1-PROPYNE
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The reaction of N,N-dichlorobenzenesulfonamide with 3-chloro-1-propyne gives 2,2,3-trichloro-1,1-di(benzenesulfonamido)propane and N-(2,3-dichloro-1-propenyl)benzenesulfonamide. These are the products from consecutive transformations, i.e., addition of N,N-dichlorobenzenesulfonamide to 3-chloro-1-propyne with the formation of N-chloro-N-(2,3-dichloro-1-propenyl)benzenesulfonamide, its reduction to N-(2,3-dichloro-1-propenyl)benzenesulfonamide or transformation by 1,3-migration of a chlorine atom to N-(2,2,3-trichloropropylidene)benzenesulfonamide, and addition of benzenesulfonamide to the latter with the formation of 2,2,3-trichloro-1,1-di(benzenesulfonamido)propane.
- Drozdova, T. I.,Kozyreva, O. B.,Levkovskaya, G. G.,Mirskova, A. N.
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p. 409 - 412
(2007/10/02)
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- Structure-activity considerations in kinetics and mechanism of chlorine exchange between chloramine-T and secondary amines
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To study the mechanism of N-chlorination of secondary amines by chloramine-T, the kinetics of the reactions of some aromatic-substituted analogues of N-chlorobenzenesulfonamide with various secondary amines were determined. The importance of amine basicity and reactivity of the N-Cl bond of the N-chlorobenzenesulfonamide was also assessed. The results indicate that a mechanism involving the un-ionized species of both reactants (i.e., a molecular mechanism), rather than an ionic mechanism, is operating and that the reaction most likely proceeds via a six-membered-ring transition state that incorporates a water molecule.
- Dannan,Hussain,Crooks,Dittert
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p. 657 - 660
(2007/10/02)
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