N-iodosuccinimide Research Articles

Synthesis of the pentasaccharide repeating unit with a conjugation-ready linker corresponding to the O-antigenic polysaccharide of Acinetobacter junii strain 65

A straightforward synthesis of the pentasaccharide with a readily available linker arm corresponding to the O-antigenic polysaccharide of Acinetobacter junii strain 65 has been achieved in good yield. The synthesis has been carried out using thioglycosides as glycosyl donor in the presence of a combination of N-iodosuccinimide (NIS) and trifluoromethanesulfonic acid (TfOH) as thiophilic activator. The yields of the glycosylation steps were very good with satisfactory stereochemistry at the glycosidic linkages. The pentasaccharide derivative has also been obtained using a one-pot iterative glycosylation strategy.

Synthesis of the pyruvic acid acetal containing tetrasaccharide repeating unit corresponding to the K82 capsular polysaccharide of Acinetobacter baumannii LUH5534 strain

An efficient synthetic strategy has been developed to achieve a pyruvic acid acetal containing tetrasaccharide repeating unit corresponding to the K82 capsular polysaccharide of Acinetobacter baumannii LUH5534 strain in very good yield. The synthetic scheme involves the use of suitably functionalized monosaccharide thioglycosides as glycosyl donors and a combination of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) as thiophilic glycosylation activator to furnish satisfactory yield of the products with appropriate stereochemistry at the glycosidic linkages. Incorporation of the (R)-pyruvic acid acetal in the D-galactose moiety was achieved in very good yield by the treatment of the diol derivative with methyl 2,2-bis(p-methylphenylthio)propionate in the presence of a combination of NIS and triflic acid.

Use of an oxazolidinone derivative of a sialyl thioglycoside as a useful glycosyl donor for α-favorable glycosidation with simple alcohols

An efficient synthesis of lauryl thioglycoside of oxazolidinones derived from N-acetyl neuraminic acid was accomplished from a known thioglycoside of Neu5Ac. The O-glycosidation reactivities of the oxazolidinones were evaluated by means of trimethylsilyl trifluoromethanesulfonate (TMSOTf) and N-iodosuccinimide (NIS) as a combined-mediator system. The glycosidation reaction of the lauryl thioglycoside with simple alcohols proceeded smoothly to yield the corresponding α-glycosides in good yields after isolation. The results suggested that the glycosylation reaction using the oxazolidinone derivative of sialic acid has excellent α-stereoselectivity and enables easy isolation of the desired product from the reaction mixture.

Convergent synthesis of the pentasaccharide repeating unit corresponding to the cell wall O-polysaccharide of Salmonella milwaukee (group U) O:43 strain

Synthesis of the pentasaccharide repeating unit of the cell O-polysaccharide produced by Salmonella milwaukee O:43 strain (group U) has been achieved in very good yield adopting a convergent stereoselective [3 + 2] block glycosylation strategy. Thioglycosides and glycosyl trichloroacetimidate derivative were used as glycosyl donors in the presence of a combination of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) as thiophilic activator and TMSOTf as trichloroacetimidate activator respectively. The stereochemical outcome of all glycosylation reactions was excellent.

Convergent Synthesis of a Pentasaccharide Containing a Rare Sugar 4‐amino‐4‐deoxy‐D‐fucose Related to the Cell Wall O‐polysaccharide of Acinetobacter baumannii 90

AbstractA convenient synthetic strategy has been developed for the synthesis of a pentasaccharide related to the cell wall O‐polysaccharide of Acinetobacter baumannii (A. baumannii) 90 in very good yield applying a stereoselective [3+2] block glycosylation reaction. The synthesis of the target pentasaccharide was challenging due to the presence of a rare sugar, 4‐amino‐4‐deoxy‐D‐fucose and several α‐glycosidic linkages in it. The construction of 1,2‐cis glycosyl linkages were achieved using a combination of copper(II) bromide and tetra‐n‐butylammonium bromide (TBAB) or a combination of N‐iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) as thiophilic glycosylation activator. Perchloric acid supported over silica (HClO4‐SiO2) mediated orthogonal glycosylation reaction has been carried out using glycosyl trichloroacetimidate derivative as donor and thioglycoside as acceptor.

Synthesis of the Pentasaccharide of the K14 Capsular Polysaccharide of Antibiotic Resistant ST25 Acinetobacter baumannii isolate, D46 and O‐Polysaccharide of Acinetobacter baumannii O11

AbstractSynthesis of the pentasaccharide corresponding to the K14 capsular polysaccharide from ST25 Acinetobacter baumannii isolate, D46 and O‐polysaccharide of Acinetobacter baumannii O11 has been achieved in very good yield using a convergent stereoselective [3+2] block glycosylation strategy. The synthetic scheme includes several regio‐ and stereose lective glycosylations as well as orthogonal glycosylation with high yield. Thioglycosides have been used as glycosyl donors using a combination of copper(II) bromide and tetra‐n‐butylammonium bromide (TBAB) as thiophilic activator for 1,2‐cis glycosylation and a combination of N‐iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf) as thiophilic activator for 1,2‐trans glycosylation. Glycosyl trichloroacetimidate derivative was used as glycosyl donor using perchloric acid supported on silica (HClO4–SiO2) as activator. A catalytic transfer hydrogenation reaction has been carried out for the removal of benzyloxy and benzylidene functional groups using triethylsilane as hydrogen source.

Regioselective Synthesis of Isoxazoles from Propargylic Alcohols via In‐situ‐formed α‐Iodo Enones/Enals

AbstractA regioselective synthesis of isoxazoles with propargyl alcohols, N‐iodosuccinimide (NIS), and N‐tert‐butyl hydroxylamine hydrochloride (t‐BuNHOH•HCl) as the reaction substrates is reported. Reaction scope investigations indicated that primary and secondary propargyl alcohols underwent this transformation smoothly to afford 5‐, 3‐, and 3,5‐substituted isoxazoles in moderate to good yields. The reaction most likely involves an electrophilic‐intercepted Meyer‐Schuster rearrangement of the propargyl alcohol, followed by intermolecular cyclocondensation of N‐tert‐butyl hydroxylamine and in‐situ‐formed α‐iodo enones/enals. This one‐pot method is regioselective and easy to perform, making it a valuable method for the construction of isoxazoles. Finally, its application was explored through the synthesis of valdecoxib.

Visible Light-Assisted Ring-Opening of Cyclic Ethers with Carboxylic Acids Mediated by Triphenylphosphine and N-Halosuccinimides.

The ring-opening of cyclic ethers (epoxide, oxetane, THF, and THP) by carboxylic acids was achieved by using N-iodosuccinimide (NIS) or N-bromosuccinimide (NBS) and triphenylphosphine under blue light. The corresponding ω-haloalkyl carboxylates were obtained under mild reaction conditions. The reaction is believed to work through a halogen bond complex between NIS (or NBS) and triphenylphosphine, which, upon irradiation with blue light, produces the key phosphine radical cation intermediate that initiates the ring-opening reactions.

Iodide-umpolung catalytic system for non-traditional amide coupling from nitroalkanes and amines.

An N-iodosuccinimide (NIS) catalyst was developed for use in the non-traditional synthesis of amide derivatives from nitroalkanes and amines. In contrast to traditional oxidative catalysis, this catalytic system involves reversing the polarities of two catalytic components (umpolung) by means of a hypervalent iodine reagent. A variety of functional groups were tolerated in the reaction, suggesting that they have the potential for use in other types of oxidative catalytic reactions.

Halogenation of aromatic compounds with N-halosuccinimides (NXS) catalysed by D-camphorsulfonic acid-BiCl3.

Aromatic bromination catalysed by 0.5-10 mol% of D-camphorsulfonic acid-BiCl3 with N-bromosuccinimides (NBS) was carried out in MeCN under air conditions, and the procedure was extended to the reactions with N-chlorosuccinimides (NCS) and N-iodosuccinimides (NIS). The halogenation of some drugs and natural products was also attempted. One-pot bromination/Suzuki-Miyaura cross-coupling and bromination/Sonogashira coupling reactions were achieved without the removal of the solvent.

Dual Function of N-Iodosuccinimide for C(sp3)-B Bond Activation.

A practical method for C(sp3)-B bond activation was developed. Using a combination of alkyl trifluoroborates and N-iodosuccinimide (NIS), various C(sp3)-heteroatom bonds were readily generated in an efficient manner. Mechanistic studies revealed the bifunctional ability of NIS: mediating the formation of reactive halogenated intermediates and activating them via halogen bonding. This electrophilic activation of the reaction center enables the utilization of general heteroatom nucleophiles, which are used in a limited capacity in traditional 1,2-metalate rearrangements.

Unusual Single Electron Transfer Reactions between Alkenes and Iodine Electrophiles†

Comprehensive SummaryThe electrophilic addition to an alkene with an electrophile has been widely studied and applied in organic synthesis. The organic chemistry textbook describes the classical reaction between an alkene and an iodine electrophile (such as elemental iodine and N‐iodosuccinimide (NIS)) as a typical ionic reaction, in which an iodonium ion is formed and then attacked by a nucleophile. However, in this article, we report a new and unusual reaction mode between an alkene and NIS; that is, a single electron transfer (SET) process occurs between these two reactants by forming an electron‐donor acceptor complex. Not only does this unusual single electron transfer reaction between an alkene and NIS add fundamentally important knowledge to organic chemistry, it also provides a valuable synthetic method as the new SET reaction mode with opposite regioselectivity as compared with the traditional ionic mode.

Expeditious Synthesis of the Hexasaccharide Repeating Unit of the Capsular Polysaccharide of Streptococcus pneumoniae Type 7A

AbstractThe hexasaccharide repeating unit corresponding to the capsular polysaccharide of Streptococcus pneumoniae type 7A has been synthesized in good yield using [3+2+1] block synthetic strategy. The synthetic strategy involved a number of challenging stereoselective glycosylation steps, which include β-selective glycosylation of l-rhamnosyl thioglycoside donor, α-selective glycosylations of 2-azido-2-deoxy-d-glucopyranosyl thioglycoside donor and d-galactopyranosyl donor together with the formation of β-glycoside of d-galactosamine moiety and α-glycoside of l-rhamnosyl moiety. Suitably functionalized thioglycosides have been used as glycosyl donors and a combination of N-iodosuccinimide (NIS) and trimethylsilyl trifluoromethanesulfonate (TMSOTf­) has been used as glycosylation promoter.

Three-Component Tandem Amidosulfenylation of Alkenes for the Synthesis of β-Succinimide Sulfides.

An environmentally benign multicomponent strategy for the amidosulfenylation of alkenes for the synthesis of β-succinimide sulfides is disclosed. In this process, common disulfides smoothly act as a sulfur-based source, and N-iodosuccinimide (NIS) is used not only as a free radical initiator but also as an N-nucleophile. A broad range of functional groups are tolerated in this reaction system.

Synthesis and molecular docking studies of novel tricyclic and angular tetracyclic benzothiadiazines via sp3‐C‐Hactivation as potential colon cancer inhibitors

AbstractThis paper describes the synthesis of tricyclic and tetracyclic benzothiadiazines and their derivatives, which are known for their versatility as bioactive agents. The starting materials were N‐cycloamino‐4‐substituted‐2‐nitrobenzenesulfonamides 8–16, which were prepared through the condensation of 4‐substituted‐2‐nitrobenzenesulfonyl chlorides 1–3 and cyclic amines 4–7. The intermediates, N‐cycloamino‐4‐substituted‐2‐sulfanilamides 17–25, were obtained through catalytic hydrogenation of N‐cycloamino‐4‐substituted‐2‐nitrobenzenesulfonamides 8–16 using a 10% palladium‐on‐charcoal catalyst. The potentially bioactive tricyclic and angular tetracyclic 1,2,4‐benzothiadizine dioxides 26–34 were then synthesized via metal‐free intramolecular N‐iodosuccinimide (NIS)‐mediated radical oxidative sp3‐C‐H activation aminative cyclization of N‐cycloamino‐4‐substituted‐2‐sulfanilamides 17–25. The yields were good to excellent (68–93%). Docking studies were conducted for N‐cycloamino‐4‐substituted‐2‐nitrobenzenesulfonamides 8–16, N‐cycloamino‐4‐substituted‐2‐sulfanilamides 17–25, and tricyclic and angular tetracyclic 1,2,4‐benzothiadizine dioxides 26–34 for colon cancer using five protein molecules. The results showed that most of the prepared ligands exhibited higher activity than the reference drugs capecitabine, capecitabine, and fluorouracil. Among the compounds synthesized, KS7, a benzothiadiazine, showed the best activity against 6KRO.

Concise synthesis of sialic acid containing hexasaccharide corresponding to group B Streptococcus type IX capsular polysaccharide

A convenient block [3 + 2+1] glycosylation strategy has been developed for the synthesis of sialic acid containing hexasaccharide repeating unit having a 2-aminoethyl linker at the reducing end corresponding to the capsular polysaccharide of Group B Streptococcus type IX strain. A disaccharide thioglycoside has been prepared applying “orthogonal latent-active” glycosylation of a thioglycoside acceptor with a thioglycoside donor. A specially designed sialic acid thioglycoside donor has been used to furnish α-glycosidic linkage. Thioglycosides were used as glycosyl donors throughout the synthetic strategy. A combination of N-iodosuccinimide (NIS) and perchloric acid supported over silica (HClO4–SiO2), a solid acid substitute, was used as a thiophilic promoter for the activation of thioglycosides.

Convergent Synthesis of the Octasaccharide Repeating Unit of the K55 Capsular Polysaccharide of Acinetobacter baumannii BAL_204 Strain

AbstractSynthesis of the octasaccharide repeating unit of the K55 capsular polysaccharide of Acinetobacter baumannii BAL_204 strain has been achieved in very good yield using a convergent [5+3] block glycosylation strategy. The pentasaccharide and trisaccharide components were synthesized using sequential stereoselective glycosylations. The p-methoxybenzyl (PMB) group was used as temporary alkyl protecting group, which was removed under the thiophilic glycosylation condition by raising the temperature. A late-stage TEMPO-mediated selective oxidation of primary hydroxyl group into carboxylic acid allowed getting the d-glucuronic acid moiety in the octasaccharide. A combination of N-iodosuccinimide (NIS) and perchloric acid supported over silica (HClO4­-SiO2) was used as a thiophilic promoter for the activation of thioglycosides. HClO4-SiO2 was also used as a solid acid activator for glycosyl trichloroacetimidate derivative.

Visible Light‐Assisted Direct C−H Acyloxylation of Polycyclic Aromatic Hydrocarbons using Carboxylic Acids

AbstractThe direct C−H acyloxylation of polycyclic aromatic hydrocarbons (PAHs) with carboxylic acids as the acyloxylating agents was achieved via the electron‐donor‐acceptor (EDA) complexes between PAHs and N‐iodosuccinimide (NIS). This visible light‐assisted metal‐free C−H acyloxylation reaction provides an easy access to the desired aryl carboxylates from readily available PAHs and aliphatic and aromatic carboxylic acids under mild reaction conditions.magnified image

An Intramolecular Radical C–N Coupling by N-Iodosuccinimide

AbstractA useful method for the formation of benzimidazole-fused phenanthridines through an intramolecular coupling of unactivated C(sp2)–H and N(sp3)–H bonds using N-iodosuccinimide (NIS) in trifluoroethanol (TFE) is presented. The synthesis of benzo[4,5]imidazo[1,2-f]phenanthridines from 2-([1,1′-biphenyl]-2-yl)-1H-benzo[d]imidazole derivatives is mild, efficient, and sustainable, with high yields and minimal waste generation. The control experiments and EPR studies were aimed at rationalizing the radical pathway of the reaction. Specifically, the use of 1,1-diphenylethylene, TEMPO, BHT, and DMPO as a free-radical spin-trapping reagent in EPR studies, allowed us to conceive a radical pathway. The gram-scale synthesis further supported the practical utility of the methodology for the field of synthetic chemistry.

Novel Benzylamine Derivatives: Synthesis, Anti-Mycobacterium Tuberculosis Evaluation and Predicted ADMET Properties

Background: Tuberculosis (TB), a disease caused by the bacillus bacteria Mycobacterium tuberculosis is one of the major contributors of ill health in the world. TB is ranked in the top 10 causes of death globally and it is the leading killer associated with a single infectious agent. According to the World Health Organization (WHO), global number of deaths associated with TB have been slowly declining with 1.3 million in reported 2016 and 2017, and 1.2 million reported in 2018 and 2019. Objective: The synthesis, characterisation, biological evaluations, and the prediction of ADMET properties of the novel benzylamine derivatives. Methods: Commercially available reagents and solvents were purchased from Sigma Aldrich and Merck (South Africa). All chemicals were used as received, unless otherwise stated. The synthesised crude compounds were purified by flash silica gel column chromatography (5 – 30% ethyl acetate in hexane). The successful formation and purity of the synthesised compounds was confirmed by NMR, HRMS and melting point. Results: The respective organic compounds were synthesised by treating 3-ethoxysalcyladehyde, 5-bromo-3-ethoxysalcyladehyde, 5-chloro-3-ethoxysalcyladehyde with various aromatic amines and the products were obtained in good to excellent yields. The 1H and 13C NMR spectra of all the products showed the appearance of the methylene signals ranging from 3.88 – 4.68 ppm and 42.25 – 52.57 ppm respectively. Additionally, most compounds showed anti-Mycobacterium tuberculosis activity that ranged between 20 and 28 µM. Conclusion: A total of 36 compounds were synthesised and successfully biologically evaluated against Mycobacterium tuberculosis (Mtb) H37RV strain. All compounds showed activity against Mtb at concentrations of > 20 µM < 28 µM with the exception of compound one that was active against Mtb at higher concentration (MIC90 > 125 µM).