Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation

• Jennifer Frommer and
• Sabine Müller

Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234

• halide to iodine, taking into account that direct iodination of purines has been claimed being troublesome [26], although not impossible [27]. For C8-iodination of adenosine, first the hydroxy groups at the sugar moiety were protected with tert-butyldimethylsilyl (TBDMS) groups. The silylated nucleoside

• 2 was dissolved in THF and lithium diisopropylamide (LDA) was added, followed by iodine in THF. The reaction temperature was kept strictly between −70 and −80 °C to make sure that iodination proceeds without further side reactions (Scheme 1) [28]. Despite the fact that the exocyclic amino group was

Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes

• Lena Reinke,
• Julia Bartl,
• Marcus Koch and
• Stefan Kubik

Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219

• spectrum at 528 nm (Figure S1 in Supporting Information File 1). Further structural information was obtained by releasing the ligand molecules from the surface of NPrac-1 with iodine, adding a known amount of 2,4,6-trimethoxy-1,3,5-triazine to the solution as an internal standard, and recording an 1H NMR

Vicinal difluorination as a C=C surrogate: an analog of piperine with enhanced solubility, photostability, and acetylcholinesterase inhibitory activity

• Yuvixza Lizarme-Salas,
• Alexandra Daryl Ariawan,
• Ranjala Ratnayake,
• Hendrik Luesch,
• Angela Finch and
• Luke Hunter

Beilstein J. Org. Chem. 2020, 16, 2663–2670, doi:10.3762/bjoc.16.216

• -workers have recently described a method for the one-step, diastereoselective 1,2-difluorination of alkenes, mediated by a hypervalent iodine catalyst [24]. The substrate scope of the Jacobsen method has certain constraints but their original report did include some examples of α,β-unsaturated amides, and

Synthesis of 4-substituted azopyridine-functionalized Ni(II)-porphyrins as molecular spin switches

• Jannis Ludwig,
• Tobias Moje,
• Fynn Röhricht and
• Rainer Herges

Beilstein J. Org. Chem. 2020, 16, 2589–2597, doi:10.3762/bjoc.16.210

• Oxone™ (Wegner et al. [19][20][21], Scheme 1). Isolation of 3 was achieved, however, a one pot approach including a subsequent Baeyer–Mills reaction to yield 10 is preferred. 1-Iodo-3-nitrosobenzene (6) cannot be prepared by oxidation of the corresponding aniline because hypervalent iodine is formed [22

Synthesis of novel fluorinated building blocks via halofluorination and related reactions

• Attila Márió Remete,
• Tamás T. Novák,
• Melinda Nonn,
• Matti Haukka,
• Ferenc Fülöp and
• Loránd Kiss

Beilstein J. Org. Chem. 2020, 16, 2562–2575, doi:10.3762/bjoc.16.208

• the larger iodine cation to a greater extent. With this in mind, we also tried the chlorofluorination of compound 19. Again, two chlorofluorinated products were formed, but only (rac)-20c could be isolated in a pure form (Scheme 12). Chlorofluorination is usually inferior in terms of the yield when

Recent developments in enantioselective photocatalysis

• Callum Prentice,
• James Morrisson,
• Andrew D. Smith and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197

• ketyl radical anion 166•−. The latter intermediate 166•− can then abstract an iodine atom from another molecule of 163 to propagate the chain reaction and generate alkyl iodide 167, which collapses to give the desired enantioenriched alkylation products 168 in moderate yields and excellent

Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners

• Shakeel Alvi and
• Rashid Ali

Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186

• yield. Next, compound 202 was treated with KI/NaNO2 under Sandmeyer reaction conditions to afford the triiodo compound 203 which on subsequent reaction with mCPBA and triflic acid (TfOH) provided the iodine-doped sumanene 204 in 68% yield. Finally, compound 204 was converted to the required

• tritellurasumanene 205 through the reaction with Te powder in the presence of tetrabutylammonium bromide (TBAB) and 2-picoline in DMSO as shown in Scheme 49. Interestingly, as can be pointed out from Scheme 49, pristine trithiasumanene 151 and triselenasumanene 206 were also obtained from the common iodine-doped

Access to highly substituted oxazoles by the reaction of α-azidochalcone with potassium thiocyanate

• Mysore Bhyrappa Harisha,
• Pandi Dhanalakshmi,
• Rajendran Suresh,
• Raju Ranjith Kumar and
• Shanmugam Muthusubramanian

Beilstein J. Org. Chem. 2020, 16, 2108–2118, doi:10.3762/bjoc.16.178

• thiocyanate 2 in the presence of several oxidants and metal salts (Table 1). The initial attempts employing iodine, CAN and ZnCl2 upon refluxing in acetonitrile for 6 hours did not yield any product (Table 1, entries 1, 2 and 4). When potassium persulfate (K2S2O8) is employed, highly substituted oxazole 3i

The biomimetic synthesis of balsaminone A and ellagic acid via oxidative dimerization

• Sharna-kay Daley and
• Nadale Downer-Riley

Beilstein J. Org. Chem. 2020, 16, 2026–2031, doi:10.3762/bjoc.16.169

• establish high-yielding and selective oxidative coupling reactions, has afforded new and greener synthetic protocols for biaryls [5][6][7]. Several oxidants, such as the salts of Ag(I&II) [8], Ti(III&IV) [9], Mn(III) [10], Ce(IV) [11], Sn(IV) [12] and Fe(III) [13], as well as the hypervalent iodine reagents

• aqueous conditions to prevent complexation of the reagent and the starting material. Of the Lewis acids used, stannic chloride proved to be the most effective oxidant for dimerization (Table 1). However, the hypervalent iodine reagents PIFA and PIDA gave better results overall, affording dimer 18 in 63

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• iodine-catalyzed Mukiyama–Michael addition of the ketene silyl acetal 104 to 103 afforded the trans-1,5-disubstituted tetrahydropyranone 105. After the generation of the C-3-exocyclic olefin and functional group manipulation, the Takai olefination [40] of the aldehyde 106 gave the trans-vinyl iodide 107

One-pot and metal-free synthesis of 3-arylated-4-nitrophenols via polyfunctionalized cyclohexanones from β-nitrostyrenes

• Haruyasu Asahara,
• Minami Hiraishi and
• Nagatoshi Nishiwaki

Beilstein J. Org. Chem. 2020, 16, 1830–1836, doi:10.3762/bjoc.16.150

• -nitrocyclohexanones. When the reaction was conducted in the presence of water, the cyclohexenes were efficiently hydrolyzed into cyclohexanones. Subsequent aromatization by heating the cyclohexanone with a catalytic amount of iodine in dimethyl sulfoxide gave 3-arylated-4-nitrophenols. The reaction of nitrostyrenes

• using iodine was then attempted (Table 2). The reaction did not proceed in toluene or acetonitrile (Table 2, entries 1 and 2), but dimethyl sulfoxide (DMSO) was effective for the aromatization, and nitrophenol 5a was obtained in 26% yield (Table 2, entry 3) [21][22][23]. This reaction proceeded

• efficiently to afford 5a in 61% yield even when the amount of iodine was decreased to 10 mol %. However further decreasing the iodine amount to 5 mol % was not effective for the conversion (Table 2, entries 4 and 5). In each case, both stereoisomers of 4a were completely consumed, and several unidentified

Synthesis of Streptococcus pneumoniae serotype 9V oligosaccharide antigens

• Sharavathi G. Parameswarappa,
• Claney L. Pereira and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2020, 16, 1693–1699, doi:10.3762/bjoc.16.140

• via a two-step process of triflation and azide substitution to produce the desired trisaccharide 24 [29]. Removal of the allyl group using iridium-catalyzed isomerization and subsequent treatment with iodine in the presence of water yielded trisaccharide acceptor 25 for the late stage [2 + 3

Fluorohydration of alkynes via I(I)/I(III) catalysis

• Jessica Neufeld,
• Constantin G. Daniliuc and
• Ryan Gilmour

Beilstein J. Org. Chem. 2020, 16, 1627–1635, doi:10.3762/bjoc.16.135

• suppressed catalysis. The prerequisite for this substructure was established by molecular editing and was complemented with a physical organic investigation of possible determinants. Keywords: α-fluoroketone; alkyne; fluorination; hypervalent iodine; organocatalysis; Introduction The venerable role of

One-pot synthesis of 1,3,5-triazine-2,4-dithione derivatives via three-component reactions

• Gui-Feng Kang and
• Gang Zhang

Beilstein J. Org. Chem. 2020, 16, 1447–1455, doi:10.3762/bjoc.16.120

• , and trifluoromethyl they smoothly took part in the three-component reaction and provided the desired products 6ja–na in moderate yields. It is noteworthy that benzaldehydes containing a halogen atom such as fluorine, chlorine, bromine, and iodine in the para and meta-positions were also compatible

An overview on disulfide-catalyzed and -cocatalyzed photoreactions

• Yeersen Patehebieke

Beilstein J. Org. Chem. 2020, 16, 1418–1435, doi:10.3762/bjoc.16.118

• conditions. In order to convert the unreactive isomer 72 to the reactive isomer 71, different isomerization methods were tested. When iodine was used as the isomerization agent, the hydrolysis of the enol moiety took place, and the irradiation with Me6Sn2 and Bu6Sn2 did not initiate any isomerization of the

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

• to afford the corresponding thietanes 66. The subsequent introduction of nucleobases then gave the corresponding thietanose nucleosides 68 [45] (Scheme 15). The treatment of 2-(allylthio)benzimidazole 69 with iodine in CHCl3 followed by aq. KOH gave (iodomethyl)thiazolobenzimidazole 70 which was

Disposable cartridge concept for the on-demand synthesis of turbo Grignards, Knochel–Hauser amides, and magnesium alkoxides

• Mateo Berton,
• Kevin Sheehan,
• Andrea Adamo and
• D. Tyler McQuade

Beilstein J. Org. Chem. 2020, 16, 1343–1356, doi:10.3762/bjoc.16.115

• -hydroxybenzaldehyde phenylhydrazone [52] or a mixture of benzoic acid and 4-(phenylazo)diphenylamine [53]. Iodine can also be used [54]. Similar concentrations were obtained by NMR titration with 1,5-cyclooctadiene as a standard (Section 1.2.10 in Supporting Information File 1) [55]. The heat released from the

Oxime radicals: generation, properties and application in organic synthesis

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Alexander S. Budnikov and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107

• a catalytic amount of iodine (Scheme 53) [142]. Aromatic β,γ-unsaturated oximes containing both electron-donating and electron-withdrawing substituents in the phenyl ring give cyclization products in good yields

Activated carbon as catalyst support: precursors, preparation, modification and characterization

• Melanie Iwanow,
• Tobias Gärtner,
• Volker Sieber and
• Burkhard König

Beilstein J. Org. Chem. 2020, 16, 1188–1202, doi:10.3762/bjoc.16.104

• be produced by salt templating or ultrasonic spray pyrolysis as well as by microwave irradiation. The resulting activated carbon materials are characterized by a variety of techniques such as SEM, FTIR, nitrogen adsorption, Boehm titrations, adsorption of phenol, methylene blue and iodine, TPD, CHNS

• groups and simultaneously increase of basic properties [10]. Phenol, methylene blue and iodine adsorption: Adsorption capacity and amount of pores of activated carbon materials are determined by using different adsorbates (phenol, methylene blue and iodine). The activated carbons are added to defined

• methylene blue or phenol solutions and are shaken for a certain time. The concentration of the adsorbates methylene blue and phenol is spectrophotometrically determined at defined absorbance wavelengths. The iodine number is determined by titration with sodium thiosulfate. Generally, the iodine number

A simple and easy to perform synthetic route to functionalized thienyl bicyclo[3.2.1]octadienes

• Dragana Vuk,
• Irena Škorić,
• Valentina Milašinović,
• Krešimir Molčanov and
• Željko Marinić

Beilstein J. Org. Chem. 2020, 16, 1092–1099, doi:10.3762/bjoc.16.96

• [3.2.1]octadiene derivatives by irradiating the toluene solution of compound's 3–7 mixture of cis- and trans-isomers in the presence of iodine (Scheme 2 and Scheme 3). The electrocyclization reactions were successfully implemented in most cases and photoproducts 8–11 were obtained in moderate yields. The

Synthesis and properties of tetrathiafulvalenes bearing 6-aryl-1,4-dithiafulvenes

• Aya Yoshimura,
• Hitoshi Kimura,
• Kohei Kagawa,
• Mayuka Yoshioka,
• Toshiki Itou,
• Dhananjayan Vasu,
• Takashi Shirahata,
• Hideki Yorimitsu and
• Yohji Misaki

Beilstein J. Org. Chem. 2020, 16, 974–981, doi:10.3762/bjoc.16.86

• ion complexes with DDQ or iodine were reported [17][18][19][20][21][22][23][24]. Peripherally thiophene-functionalized TTFs, as potential precursors to conducting polymers, and organic metals were also prepared and characterized [25][26][27][28][29]. To design more tempting molecules, the attachment

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• and HEH act respectively as electron and hydrogen donors. The protocol was efficient for dehalogenations with bromine- and iodine-containing acetophenone derivatives (75–98% yields). However, it was much less efficient with chloro ketones (12–40% yields) and not effective with α-bromo esters and α

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• leading to an electron transfer to the iodine atom, thereby liberating iodide, an alkyl radical, and a radical cation of the Cu complex. Recombination of the latter radicals leads to the formation of the desired silane along with the regeneration of the active Cu species (Scheme 8). This strategy was also

Copper-catalyzed O-alkenylation of phosphonates

• Nuria Vázquez-Galiñanes,
• Mariña Andón-Rodríguez,
• Patricia Gómez-Roibás and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2020, 16, 611–615, doi:10.3762/bjoc.16.56

• valuable enol phosphonates in very good yields. Keywords: alkenylation; copper; C(sp2)–O bond formation; hypervalent iodine; phosphonates; Introduction Organophosphorus compounds represent an important class of products with a wide range of applications in biology, agriculture and synthetic organic

• (alkenyl)iodonium salts, which are air- and moisture-stable, nontoxic and easy to prepare compounds, have become efficient reagents for mild and selective arylation and alkenylation reactions in organic synthesis [16][17][18]. In particular, the use of these hypervalent iodine reagents in copper catalysis

Recent advances in photocatalyzed reactions using well-defined copper(I) complexes

• Mingbing Zhong,
• Xavier Pannecoucke,
• Philippe Jubault and
• Thomas Poisson

Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42

• of the ligand iodide for DAP (path III). Another possibility was the trapping of the radical with the iodine ligand of the [Cu(II)] catalyst (path IV). In 2019, Reiser’s group described a chlorosulfonylation reaction of alkenes and alkynes with [Cu(I)(dap)2]Cl or [Cu(II)(dap)2]Cl2 under visible light

• 2012, Collins and co-workers described a copper-catalyzed photocyclization to synthesize [5]helicene (Scheme 29) [43]. Using the in situ-formed [Cu(I)(dmp)(xantphos)]BF4 (25 mol %) in the presence of iodine and propylene oxide as the oxidant system under visible light irradiation, [5]helicene was

• oxidative quenching. First, the excited [Cu(I)]* species was oxidized in the presence of iodine, furnishing a [Cu(II)] complex. Then, an oxidation of the diarylamine occurred, generating the N-centered radical cation, which undergoes an intramolecular cyclization. A final oxidation of the aryl radical