Novel amide-functionalized chloramphenicol base bifunctional organocatalysts for enantioselective alcoholysis of meso-cyclic anhydrides

• Lingjun Xu,
• Shuwen Han,
• Linjie Yan,
• Haifeng Wang,
• Haihui Peng and
• Fener Chen

Beilstein J. Org. Chem. 2018, 14, 309–317, doi:10.3762/bjoc.14.19

• development of chiral bifunctional urea 1 [35], thiourea 2 and 3 [36][37], sulfonamide 4 [38][39][40] and squaramide 5 [38][39][40] catalysts derived from chloramphenicol base (Figure 1), which showed excellent reactivity and enantioselectivity for this asymmetric transformation. A typical example of the

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation and chlorination. Part 2: Use of CF₃SO₂Cl

• Hélène Chachignon,
• Hélène Guyon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2800–2818, doi:10.3762/bjoc.13.273

• nature of the substituents of the sulfonamide group showed little influence on the efficiency of the process. On the contrary, better results were obtained when realising the reaction on substrates featuring electron-donating groups on the phenyl ring directly bound to the nitrogen atom. It was also

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• using a chiral sulfonamide as chiral auxiliary afforded 99 (de > 98:2). Finally, group manipulations, i.e., deprotection of the amine, Fmoc reprotection and oxidation gave the isostere 100. Then, Pannecoucke’s group proposed a modified and more versatile approach where the monofluoroalkene 102 was

Synthesis of benzannelated sultams by intramolecular Pd-catalyzed arylation of tertiary sulfonamides

• Valentin A. Rassadin,
• Mirko Scholz,
• Anastasiia A. Klochkova,
• Armin de Meijere and
• Victor V. Sokolov

Beilstein J. Org. Chem. 2017, 13, 1932–1939, doi:10.3762/bjoc.13.187

• formation of a 2,3-diarylindole was observed under the same conditions. Keywords: arylation; fused-ring systems; indole formation; palladium catalysis; sultams; Introduction The sulfonamide functional group stands out as one of the most important pharmacophores. At the same time, cyclic sulfonamides

• methyl iodide (Scheme 2). Unfortunately, this apparently simple transformation yielded a mixture of C-, N- and C,N-methylation products due to similar reactivities of the C- and N-nucleophilic centers in 3a. At best, the tertiary sulfonamide 5 was isolated in 32% yield. In contrast to the behavior of 3a

• problem in the alkylation of the sulfonamide 3a, the sequence of steps was reversed. Thus, 2-iodo-N-(4-methoxybenzyl)anilines 7a–g were prepared by reduction of the Schiff bases obtained from 2-iodoanilines 1a–g and 4-methoxybenzaldehyde with sodium cyanoborohydride in a mixture of glacial acetic acid and

Mechanochemical synthesis of thioureas, ureas and guanidines

• Vjekoslav Štrukil

Beilstein J. Org. Chem. 2017, 13, 1828–1849, doi:10.3762/bjoc.13.178

• potassium carbonate as the base was necessary to deprotonate the sulfonamide and thus increase its reactivity. After milling for 2 hours with the corresponding iso(thio)cyanate, the sulfonyl (thio)ureas 42a–c were isolated in excellent yields, for example the drug tolbutamide (1) in 92% (Scheme 17a

• sulfonamide–isocyanate coupling. The mechanochemical EDC-mediated amide bond formation [50] was successful and provided the intermediate 43 in 74% yield. In the second step, coupling of the sulfonamide intermediate 43 with 1.2 equivalents of cyclohexyl isocyanate in the presence of 5 mol % of CuCl and

Chiral phase-transfer catalysis in the asymmetric α-heterofunctionalization of prochiral nucleophiles

• Johannes Schörgenhumer,
• Maximilian Tiffner and
• Mario Waser

Beilstein J. Org. Chem. 2017, 13, 1753–1769, doi:10.3762/bjoc.13.170

• conditions [90]. Key to success in this spectacular report was the use of the systematically optimized sulfonamide-containing phosphonium salt J1. With this catalyst, they were able to achieve high selectivities in the α-chlorination of 1 with N-chlorophthalimide (13) as the Cl-source under H2O-rich

Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds

• M. Fernanda N. N. Carvalho,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122

• ], or oxidised to oxaziridines used as efficient chiral oxidising reagents [13][17][18][19]. The reaction of the oxoimide 3 with two equivalents of the lithium salt of a terminal alkyne leads to compounds 4 where two alkynyl substituents, a sulfonamide and a hydroxy group are found in vicinal positions

• coincide in 13 but are approximately 2 ppm apart in 12. Compounds 12 show a signal for the C=O near 206 ppm and one for the sulfonamide carbon at about 65 ppm. In compounds 13, there is a signal for the C=N around 194 ppm and one for the tertiary alcohol carbon near 73 ppm. All other signals of the camphor

• in the presence of Zn/HOAc, as shown in Scheme 4. The product shows an IR stretching vibration at 1760 cm−1 and a 13C NMR signal at 209.7 ppm for the unreacted C=O group. The presence of the sultam can be deduced from the NH stretching vibration at 3180 cm−1, a 13C signal of the sulfonamide carbon at

DMAP-assisted sulfonylation as an efficient step for the methylation of primary amine motifs on solid support

• Johnny N. Naoum,
• Koushik Chandra,
• Dorit Shemesh,
• R. Benny Gerber,
• Chaim Gilon and
• Mattan Hurevich

Beilstein J. Org. Chem. 2017, 13, 806–816, doi:10.3762/bjoc.13.81

• introduction of the o- or p-nitrobenzenesulfonyl groups to primary amines in the first step. The semi-protected sulfonamides can then undergo a selective mono-methylation via Mitsunobu reaction or by direct methylation. The reaction is completed by the selective removal of the sulfonamide group. Miller and

Chromium(II)-catalyzed enantioselective arylation of ketones

• Gang Wang,
• Shutao Sun,
• Ying Mao,
• Zhiyu Xie and
• Lei Liu

Beilstein J. Org. Chem. 2016, 12, 2771–2775, doi:10.3762/bjoc.12.275

• ) was selected as the model reaction for optimization employing Kishi’s oxazoline/sulfonamides as the chiral ligands. A series of oxazoline/sulfonamide ligands (L1–L8) were tested and the results were summarized in Table 1. Four subgroups of R1 were studied (entries 1–4, Table 1) and isopropyl

• ) was used, enantiopure indan-1-ol was obtained in 70% yield and 82% ee. Conclusion In summary, we have developed the first Cr-catalyzed enantioselective arylation of ketones in an intramolecular version using oxazoline/sulfonamide L8 as the catalyst. Both aliphatic and arylaliphatic ketones proceeded

Enduracididine, a rare amino acid component of peptide antibiotics: Natural products and synthesis

• Darcy J. Atkinson,
• Briar J. Naysmith,
• Daniel P. Furkert and
• Margaret A. Brimble

Beilstein J. Org. Chem. 2016, 12, 2325–2342, doi:10.3762/bjoc.12.226

• (1) and (±)-allo-enduracididine (3) reported by Du Bois et al. arose from the methodology for the conversion of alkenes to diamines via a cyclic sulfonamide intermediate using rhodium catalysis (Scheme 9) [63]. The reaction proceeds with formation of an intermediate aziridine 53 which rearranges upon

• addition of sodium iodide to afford the desired cyclic sulfonamide 54. For the synthesis of (±)-enduracididine (1) and (±)-allo-enduracididine (3), protected (±)-allylglycine 55 was treated with BocNHS(O)2NH2, MgO, Rh2(esp)2 and PhI(OAc)2 in isopropyl acetate followed by sodium iodide to afford cyclic

• sulfonamide 56 in 56% yield as a 1:1 mixture of diastereomers (Scheme 10). Selective deprotection of the sulfonamide Boc group allowed separation of diastereomers 57 and 58 via chromatography which were then converted to Tces (2,2,2-trichloroethoxysulfonyl) protected guanidines 59 and 60. Global deprotection

Chiral cyclopentadienylruthenium sulfoxide catalysts for asymmetric redox bicycloisomerization

• Barry M. Trost,
• Michael C. Ryan and
• Meera Rao

Beilstein J. Org. Chem. 2016, 12, 1136–1152, doi:10.3762/bjoc.12.110

• asymmetric redox bicycloisomerization of 1,6- and 1,7-enynes. This complex was used to synthesize a broad array of [3.1.0] and [4.1.0] bicycles. Sulfonamide- and phosphoramidate-containing products could be deprotected under reducing conditions. Catalysis performed with enantiomerically enriched propargyl

• steps. Heterocycle 7 is a bench stable white powder that can be stored indefinitely in a dessicator without any noticeable decomposition. The sulfonamide moiety activates sulfur towards nucleophilic addition, making the first addition of an organometallic reagent faster than the second. By performing

• decided to initiate our efforts on 1,7-enyne sulfonamide 13 for reaction optimization. Table 1 showcases our initial experiments. With 3 mol % of CpRu-sulfoxide catalyst 1 in THF at 40 °C, 14 could be obtained in a 69% yield and a promising 26.5:73.5 er (Table 1, entry 1). This important first experiment

Catalytic asymmetric synthesis of biologically important 3-hydroxyoxindoles: an update

• Bin Yu,
• Hui Xing,
• De-Quan Yu and
• Hong-Min Liu

Beilstein J. Org. Chem. 2016, 12, 1000–1039, doi:10.3762/bjoc.12.98

• to the total synthesis of natural TMC-95A. In 2015, Yang and co-workers reported α-amino acid sulfonamide (cat. 7)-catalyzed aldol reactions of ketones with isatins under neat conditions (Scheme 20) [36]. Interestingly, the reactions proceeded smoothly, giving the desired products in high yields (up

The synthesis of functionalized bridged polycycles via C–H bond insertion

• Jiun-Le Shih,
• Po-An Chen and
• Jeremy A. May

Beilstein J. Org. Chem. 2016, 12, 985–999, doi:10.3762/bjoc.12.97

• generated the tosylamine-bridged bicycle 51. The aminal in 51 could be transformed to a methyl hemiaminal, and then later a second C–H bond insertion by another nitrene targeted the less activated C–H bond to form the ring-fused piperidine 52. Thus, the pendant sulfonamide acted as a tool for multiple

1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis

• Antonia Mielgo and
• Claudio Palomo

Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90

• catalytic cycle, while providing the final product VIII. The authors propose a bifunctional behavior of the catalyst, wherein a hydrogen bonding interaction between the sulfonamide N–H and the thiazolone enolate controls its addition to the C–C double bond, which is the key step for asymmetric induction

Strecker degradation of amino acids promoted by a camphor-derived sulfonamide

• M. Fernanda N. N. Carvalho,
• M. João Ferreira,
• Ana S. O. Knittel,
• Maria da Conceição Oliveira,
• João Costa Pessoa,
• Rudolf Herrmann and
• Gabriele Wagner

Beilstein J. Org. Chem. 2016, 12, 732–744, doi:10.3762/bjoc.12.73

• decarboxylation reaction (azomethine ylides 7 and ene-sulfonamide 8). Figure 11 shows the structures and relative energies of geometry-optimized isomeric primary products 7 and 8, as well as their tautomeric products 9, 10 and 11 containing the newly formed C–H bonds. These secondary isomers are considerably more

• of water is necessary for this step. 2. The fastest tautomerization in the reaction mixture occurs between 7a and 8 (the ene-sulfonamide). The low barriers (8.4 and 10.6 kcal/mol) should allow the equilibrium to be established rapidly. On the other hand, there is no possibility of proton transfer

• system as in ninhydrin. The resulting intermediates, azomethine ylides or ene-sulfonamide, undergo water-catalyzed tautomerization reactions followed by hydrolysis of the C=N bonds to form amines with a new chiral center at the former C=O group of compound 1. The isolated compound 2 is derived from one

Supported bifunctional thioureas as recoverable and reusable catalysts for enantioselective nitro-Michael reactions

• José M. Andrés,
• Miriam Ceballos,
• Alicia Maestro,
• Isabel Sanz and
• Rafael Pedrosa

Beilstein J. Org. Chem. 2016, 12, 628–635, doi:10.3762/bjoc.12.61

• thiourea I [30] onto sulfonylpolystyrene resin leading to catalysts II–V (Figure 1), which differ in the length of the diamine linker or in the substitution pattern of the nitrogen in the sulfonamide. These materials, and the related unsupported thiourea VI, have been previously tested as excellent

• conditions, supported catalyst V, which differs from IV in the substitution pattern of the sulfonamide, was the best catalyst for the addition of both 2a and 3a to nitrostyrene, yielding products 4aa and 5aa, respectively, in much better yield maintaining the stereoselectivity in shorter reaction time

The aminoindanol core as a key scaffold in bifunctional organocatalysts

• Isaac G. Sonsona,
• Eugenia Marqués-López and
• Raquel P. Herrera

Beilstein J. Org. Chem. 2016, 12, 505–523, doi:10.3762/bjoc.12.50

• , the asymmetric Diels–Alder (D–A) reaction between the N-sulfonamide-3-hydroxy-2-pyridone-based dienes 52 and different dienophile substrates was developed using the bifunctional cis-2-trialkylaminoindanol organocatalyst ent-41 [56]. We show herein the reactivity of this family of dienes with several

Copper-catalyzed intermolecular oxyamination of olefins using carboxylic acids and O-benzoylhydroxylamines

• Brett N. Hemric and
• Qiu Wang

Beilstein J. Org. Chem. 2016, 12, 22–28, doi:10.3762/bjoc.12.4

• of 1,2-oxyamino products. For example, most oxyamination methods are limited to the installation of amide or sulfonamide derivatives. The direct installation of electron-rich amino groups, especially tertiary cyclic amines, remains an unsolved problem. Furthermore, most methods employ inflexible

Beyond catalyst deactivation: cross-metathesis involving olefins containing N-heteroaromatics

• Kevin Lafaye,
• Cyril Bosset,
• Lionel Nicolas,
• Amandine Guérinot and
• Janine Cossy

Beilstein J. Org. Chem. 2015, 11, 2223–2241, doi:10.3762/bjoc.11.241

• -pyrido-diazocine 46 with an excellent yield of 94% (Scheme 18) [56]. The presence of the two sulfonamide substituents on the pyridyl ring might decrease the basicity of the nitrogen atom thus allowing the metathesis to proceed. Steric hindrance due to the C2 substitution may also prevent the pyridine

Recent advances in copper-catalyzed C–H bond amidation

• Jie-Ping Wan and
• Yanfeng Jing

Beilstein J. Org. Chem. 2015, 11, 2209–2222, doi:10.3762/bjoc.11.240

• depending on the properties of both aryl substrate and amide nucleophile (Scheme 10). It is worth to mention that Pan and co-workers recently disclosed N-fluorobenzene sulfonimides to be employed as the source of sulfonamide to enable the synthesis of N-heteroaryl sulfonimides via copper-catalyzed aryl C–H

• catalytic protocol was later developed by Mizuno et al. [74] for the amidation of terminal alkynes using lactam, sulfonamide or cyclic carbamates. The application of Cu(OH)2 as heterogeneous catalyst allowed the synthesis of ynamides 77 with moderate to excellent yield under air (Scheme 20). A latest work

Profluorescent substrates for the screening of olefin metathesis catalysts

• Raphael Reuter and
• Thomas R. Ward

Beilstein J. Org. Chem. 2015, 11, 1886–1892, doi:10.3762/bjoc.11.203

• -methoxynaphthalene-1-sulfonamide moiety that is connected by an internal double bond to a 2,4-dinitroaniline core, acting as a fluorescence quencher [17]. Both the sulfonamide of the fluorophore and the aniline group of the quencher bear another allyl group. Upon relay ring-closing metathesis, the fluorophore and

• was achieved relying on two converging synthons (Scheme 2). The fluorophore part of the molecule was synthesized starting from sodium 5-methoxynaphthalene-1-sulfonate (11), which was prepared according to a known procedure [25]. It was then transformed to the corresponding allyl sulfonamide 12 by

• platereader was used. N-Allyl-5-methoxynaphthalene-1-sulfonamide (12). To a DMF solution (30 mL) of sodium 5-methoxynaphthalene-1-sulfonate (11, 1.30 g, 5.00 mmol, 1.00 equiv), cooled on an ice bath, thionyl chloride (1.09 mL, 15.0 mmol, 3.00 equiv) was added dropwise. After the complete addition, the ice

Recent applications of ring-rearrangement metathesis in organic synthesis

• Sambasivarao Kotha,
• Milind Meshram,
• Priti Khedkar,
• Shaibal Banerjee and
• Deepak Deodhar

Beilstein J. Org. Chem. 2015, 11, 1833–1864, doi:10.3762/bjoc.11.199

• skeletally diverse bi-, and tricyclic sultam derivatives (sulfonamide analogs) using norbornenyl sultam 272 as a core unit assembled by an intramolecular Diels–Alder (IMDA) reaction via a domino ROM–RCM–CM cascade. Diversity has been incorporated by using various cross-metathesis partners (Scheme 56). Basso

Fates of imine intermediates in radical cyclizations of N-sulfonylindoles and ene-sulfonamides

• Hanmo Zhang,
• E. Ben Hay,
• Stephen J. Geib and
• Dennis P. Curran

Beilstein J. Org. Chem. 2015, 11, 1649–1655, doi:10.3762/bjoc.11.181

• -dihydropyrroles also presumably form spiro-imines as primary products. However, the lactam carbonyl group facilitates the ring-opening of these cyclic imines by a new pathway of hydration and retro-Claisen-type reaction, providing rearranged 2-(2'-formamidoethyl)oxindoles. Keywords: ene-sulfonamide; imine

• the original substrates 1 by swapping the locations of the radical precursor (halide) and the radical acceptor (ene-sulfonamide). The expected products of these reactions, imines like 19, could possibly be used to make spirocyclic oxindole natural products like coerulescine [18], horsfiline [19][20

• needed for the radical precursors was made in high yield as shown in Scheme 3. Vilsmeier–Haack formylation [25] of ene-sulfonamide 20 was followed by sodium chlorite oxidation [26] of the resulting aldehyde (90% yield over two steps). The radical precursors 22–24 were readily made in 54–69% yield by

Selected synthetic strategies to cyclophanes

• Sambasivarao Kotha,
• Mukesh E. Shirbhate and
• Gopalkrushna T. Waghule

Beilstein J. Org. Chem. 2015, 11, 1274–1331, doi:10.3762/bjoc.11.142

• sulfonamide derivative in preparing glycophane molecule (Scheme 6). Haley and Langsdorf [90] have reported the synthesis of a cyclophane-containing octacobalt complex 49 using the Glaser–Eglinton coupling reaction [91] as a key step (Scheme 7). In this regard, palladium-catalyzed alkynylation of 1,4

Intermolecular addition reactions of N-alkyl-N-chlorosulfonamides to unsaturated compounds

• Gerold Heuger and
• Richard Göttlich

Beilstein J. Org. Chem. 2015, 11, 1226–1234, doi:10.3762/bjoc.11.136

• as such electrophilic intermediates for an efficient intermolecular addition reaction. Addition reactions with N-alkyl-N-halosulfonamides to unsaturated compounds have not been examined in detail so far. In earlier works Komori added a secondary N-chloro-sulfonamide to 1-hexene under photoirridation

• an N-alkyl substituent, which we anticipated to generate readily from the corresponding N-chloroamides by electron transfer from copper(I) catalysts. Results and Discussion The N-chlorosulfonamides can be easily prepared by reaction of the sulfonamide with calcium hypochlorite and moist alumina [34

• better results whilst rising the temperature to 75 °C and adding an excess of styrene increased the yield to 43%. Under these conditions the N-chlorosulfonamide 2a was completely consumed, undesired products were the sulfonamide 1a as well as oligostyrenes. The oligomerisation should be slowed down by