Synthesis of acremines A, B and F and studies on the bisacremines

• Nils Winter and
• Dirk Trauner

Beilstein J. Org. Chem. 2019, 15, 2271–2276, doi:10.3762/bjoc.15.219

• biogenetic precursor of acremines A (1) and B (2), we wanted to access these antifungal derivatives through selective oxidations. Indeed, treatment of 5 with IBX preferentially oxidized the C1-allylic alcohol, giving 1 in respectable yield. Prolonged treatment (9 h) of 5 with a large excess of IBX oxidized

Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• tert-butyl ester 13a to the alcohol by portionwise addition of DIBAL and careful temperature control (slow warm-up from −78 to −30 °C) afforded the alcohol without α-epimerization, which was oxidized to aldehyde 15 (IBX, Scheme 3). Adamantyl ester 14 resisted reduction under the same conditions and was

Synthesis of eunicellane-type bicycles embedding a 1,3-cyclohexadiene moiety

• Alex Frichert,
• Peter G. Jones and
• Thomas Lindel

Beilstein J. Org. Chem. 2018, 14, 2461–2467, doi:10.3762/bjoc.14.222

• place. Thus, we reduced the ester function of dienol triflate 11 to the alcohol (DIBAL-H, DCM, −78 °C), followed by oxidation to aldehyde 15 (IBX, Scheme 2). Fortunately, the cyclohexadiene moiety survived the oxidation conditions, which was not the case when using PCC or MnO2. Subsequent Sonogashira

• 18 to the acyloin (IBX, MeCN) and subsequent reduction (LiAlH4, THF, Scheme 2). Diastereomers 18 and 19 show distinct sets of NMR signals. The largest chemical shift differences are observed for the secondary carbinol group (δ2-H 5.18, δC2 73.1 for 18 vs δ2-H 4.14, δC2 87.2 for 19). For diol 18, we

The mechanochemical synthesis of quinazolin-4(3H)-ones by controlling the reactivity of IBX

• Md Toufique Alam,
• Saikat Maiti and
• Prasenjit Mal

Beilstein J. Org. Chem. 2018, 14, 2396–2403, doi:10.3762/bjoc.14.216

• intramolecular control. At maximum contact of the reacting substances, i.e., under solvent-free mechanochemical conditions, 2-aminobenzamides, aryl-, alkylaldehydes and the iodine(V) reagent o-iodoxybenzoic acid (IBX) led to substituted quinazolin-4(3H)-one derivatives in fair yields. Keywords: ball-mill

• ; contact explosive; IBX; mechanochemical synthesis; quinazolin-4(3H)-one; Introduction An iodine and ammonia mixture is a well-known contact explosive due to formation of NI3 [1]. Similarly, hypervalent iodines as oxidizing compounds [2] react violently with amines under solvent-free conditions [3

• focus on the development of synthetic methods using iodine-based reagents [21][22][23][24][25][26], we here report a method for the synthesis of quinazolin-4(3H)-ones [27][28] (Figure 1) from 2-aminobenzamide and aldehydes in the presence of o-iodoxybenzoic acid (IBX) [29]. However, when mixing

Stereoselective total synthesis and structural revision of the diacetylenic diol natural products strongylodiols H and I

• Pamarthi Gangadhar,
• Sayini Ramakrishna,
• Ponneri Venkateswarlu and
• Pabbaraja Srihari

Beilstein J. Org. Chem. 2018, 14, 2313–2320, doi:10.3762/bjoc.14.206

• side. Towards this, the free secondary hydroxy group in 25 was masked as its corresponding TBDPS ether 26 and then treated with PPTS in MeOH [36] to afford the disilylated primary alcohol 27 in 95% yield. Treatment of alcohol 27 with IBX [37] furnished the corresponding aldehyde 14 which was subjected

• h, 95%; (c) IBX, THF/DMSO, 0 °C to rt, 1 h, 97%; (d) 15, n-BuLi, THF, −78 °C to rt, 2 h, 83%; (e) TBAF, THF, 0 °C to rt, 2 h, 85%. Synthesis of compound 25a. Reagents and conditions: (a) (R)-CBS catalyst, BH3·DMS, −50 °C, 16 h, 86%. Synthesis of strongylodiol I (10a). Reagents and conditions: (a) (i

• ) TBDPSCl, imidazole, CH2Cl2, 0 °C to rt, 1 h, 96%; (ii) PPTS, MeOH, 0 °C to rt, 2 h, 87%; (iii) IBX, DMSO/THF 1:1, 0 °C to rt, 1 h, 98%; (b) 16, n-BuLi, THF, −78 °C to rt, 2 h, 81%; (c) TBAF, THF, 0 °C to rt, 2 h, 82%. Comparison of 1H and 13C NMR data of strongylodiol H (isolated natural product vs

Hypervalent iodine compounds for anti-Markovnikov-type iodo-oxyimidation of vinylarenes

• Igor B. Krylov,
• Stanislav A. Paveliev,
• Mikhail A. Syroeshkin,
• Alexander A. Korlyukov,
• Pavel V. Dorovatovskii,
• Yan V. Zubavichus,
• Gennady I. Nikishin and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2018, 14, 2146–2155, doi:10.3762/bjoc.14.188

• the examined hypervalent iodine oxidants (PIDA, PIFA, IBX, DMP) PhI(OAc)2 proved to be the most effective; yields of iodo-oxyimides are 34–91%. A plausible reaction pathway includes the addition of an imide-N-oxyl radical to the double C=C bond and trapping of the resultant benzylic radical by iodine

• %) was obtained using PhI(OAc)2 (Table 1, entry 2). Other iodine-based oxidants, such as PhI(OCOCF3)2 (Table 1, entry 10, yield 31%), IBX (Table 1, entries 11 and 12, yield 32–54%), DMP (Table 1, entries 13–14, yield 52%), showed less efficacy in this process. Peroxide oxidants, such as TBHP, TBAI/TBHP

• mmol) was added. In the additional experiments compounds 3ca and 3ga were prepared using IBX (140 mg, 0.50 mmol) or DMP (64 mg, 0.15 mmol) instead of PhI(OAc)2. After stirring for 10 min under air atmosphere at 20–25 °С, CH2Cl2 (30 mL) was added. The resulting mixture was washed with an aqueous

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• oxidants are employed. For example, the oxidation of alcohols to carbonyls traditionally requires strong oxidants (Cr(VI) species, IBX, DMP), whereas similar reactions using photochemical methods can utilise oxygen (O2) as the oxidising agent. The oxidising agent can accept electrons either from the

Preparation and X-ray structure of 2-iodoxybenzenesulfonic acid (IBS) – a powerful hypervalent iodine(V) oxidant

• Irina A. Mironova,
• Pavel S. Postnikov,
• Rosa Y. Yusubova,
• Akira Yoshimura,
• Thomas Wirth,
• Viktor V. Zhdankin,
• Victor N. Nemykin and
• Mekhman S. Yusubov

Beilstein J. Org. Chem. 2018, 14, 1854–1858, doi:10.3762/bjoc.14.159

• hypervalent iodine compounds as stoichiometric reagents or catalysts has experienced an explosive growth [1][2][3][4][5][6][7][8]. Hypervalent iodine(V) compounds represent an important class of oxidative reagents extensively employed in organic synthesis [9][10][11]. 2-Iodoxybenzoic acid (IBX) and the

• product of its acetylation Dess–Martin periodinane (DMP) are the most common oxidants used for selective oxidation of alcohols to carbonyl compounds as well as for a variety of other synthetically useful oxidative transformations [10][11]. IBX and DMP are mild oxidants with a relatively low reactivity

• alcohols based on 2-iodoxybenzenesulfonic acid (IBS) as the active species [12][13]. IBS (or its sodium salt) is much more active as catalyst than IBX derivatives. In particular, it can be used as a highly efficient and selective catalyst (0.05–5 mol %) for the oxidation of primary and secondary alcohols

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• -catalyzed 1,2-acetoxysulfenylation of Baylis–Hillman products at 50 °C under an oxygen atmosphere as shown in Scheme 35 [70]. The β-ketomethylene 94 substrate was generated in situ from the oxidation of Baylis–Hillman product 93 using a hypervalent iodine reagent (iodoxybenzoic acid, IBX) in an ionic liquid

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• ]. Review Tandem additions λ5-Iodanes such as the Dess–Martin periodinane or IBX [26], and λ3-iodanes such as benziodoxolones [27], are versatile reagents in organic synthesis. These are often used, respectively, for the oxidation of alcohols or carbonyl compounds, and in atom-transfer reactions. These

• of the first studies documenting the use of the iodoarene moiety as a building block in synthesis has been reported in 2004. The λ5-iodane reagent IBX has been shown to promote the α-functionalization of ketones following the introduction of the 2-iodobenzoic acid motif (Scheme 2a) [28]. Mono- and

• stereoselective trans iodo-benzoylation of glycals using a combination of IBX and molecular iodine, that is considered as a source of I+ formed from the in situ generated hypoiodite species [30]. The controlled oxidation of various N-(alkyl)- and N-(aryl)pyrroles with Dess–Martin periodinane also leads to

Rapid transformation of sulfinate salts into sulfonates promoted by a hypervalent iodine(III) reagent

• Elsa Deruer,
• Vincent Hamel,
• Samuel Blais and
• Sylvain Canesi

Beilstein J. Org. Chem. 2018, 14, 1203–1207, doi:10.3762/bjoc.14.101

• ). To verify our hypothesis tosyl-sulfinate 1 was treated with iodanes such as sodium periodate (NaIO4), Dess-Martin periodinane (DMP) [33], 2-iodoxybenzoic acid (IBX) [34], (diacetoxyiodo)benzene (DIB), phenyliodine(III) bis(trifluoroacetate) (PIFA) in the presence of methanol. (III)-Iodanes and (V

• )-iodanes were both acceptable substrates, but the process was inefficient with (VII)-iodane species. We surmise that IBX and DMP are rapidly reduced to a (III)-iodane in the presence of an alcohol, and that this species is most likely the reagent promoting the formation of compound 4a. Iodine and N

• -iodosuccinimide (NIS) were also tested; it appeared that this process was much more efficient in the presence of iodane sources (Table 1). DIB was chosen as the hypervalent iodine reagent of choice since it is more compatible with alcohols than IBX or DMP. The reaction proceeded in modest to good yields depending

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

• repeated the synthesis of 12 through a molecular bromination–dehydrobromination sequence starting with 162 [137]. Hypervalent iodine(V)-based reagents such as IBX (or 2-iodoxybenzoic acid) and Dess–Martin periodinane (DMP) are commonly used in organic synthesis as oxidizing agent to form both unsaturated

• carbonyl compounds and conjugated aromatic carbonyl systems. Nicolaou’s group reported a general method for the mild, swift, and highly efficient oxidation of alcohols, ketones, and aldehydes to unsaturated compounds in one pot (Scheme 30) [138][139]. Accordingly, an IBX-controlled dehydrogenation through

Iodine(III)-mediated halogenations of acyclic monoterpenoids

• Laure Peilleron,
• Tatyana D. Grayfer,
• Joëlle Dubois,
• Robert H. Dodd and
• Kevin Cariou

Beilstein J. Org. Chem. 2018, 14, 1103–1111, doi:10.3762/bjoc.14.96

• NIS [21] and does not require the use of a strong oxidant such as IBX [22]. Compared to the standard procedure for the preparation of acetoxyhypohalites that requires the use of expensive and potentially toxic silver salts [23], our method offers a more practical alternative. It also differs from the

Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

• Toshifumi Dohi,
• Shohei Ueda,
• Kosuke Iwasaki,
• Yusuke Tsunoda,
• Koji Morimoto and
• Yasuyuki Kita

Beilstein J. Org. Chem. 2018, 14, 1087–1094, doi:10.3762/bjoc.14.94

• single-electron-transfer (SET) reactivities [33][34][35][36][37] allow selective activation of the benzylic C(sp3)–H bond for oxidative functionalization and coupling reactions. Initially, the SET oxidation ability of pentavalent iodine reagents, especially o-iodoxybenzoic acid (IBX), in benzylic

• determined to be the best in terms of product yield. No reaction was observed in the absence of sodium bromide (Table 1, entry 9) and other representative hypervalent iodine(III) reagents, such as PIFA and PhI(OH)OTs, and pentavalent Dess–Martin periodinane and IBX, were inferior for this carboxylation when

Hypervalent iodine-mediated Ritter-type amidation of terminal alkenes: The synthesis of isoxazoline and pyrazoline cores

• Sang Won Park,
• Soong-Hyun Kim,
• Jaeyoung Song,
• Ga Young Park,
• Darong Kim,
• Tae-Gyu Nam and
• Ki Bum Hong

Beilstein J. Org. Chem. 2018, 14, 1028–1033, doi:10.3762/bjoc.14.89

• and PIDP (bis(tert-butylcarbonyloxy)iodobenzene) much better yields were obtained (Table 1, entries 2–4), with PhI(OAc)2 proving to be the best (Table 1, entry 5). Refluxing conditions further improved the yield (Table 1, entry 6). Additionally, other cyclic hypervalent iodine oxidants such as IBX (2

2-Iodo-N-isopropyl-5-methoxybenzamide as a highly reactive and environmentally benign catalyst for alcohol oxidation

• Takayuki Yakura,
• Tomoya Fujiwara,
• Akihiro Yamada and
• Hisanori Nambu

Beilstein J. Org. Chem. 2018, 14, 971–978, doi:10.3762/bjoc.14.82

• -iodoxybenzoic acid (IBX, 2) [11] are well known as representative environmentally benign oxidants for alcohol oxidation (Figure 1). However, despite the utility and versatility of these oxidants, they still have several drawbacks: both are potentially explosive, DMP is moisture-sensitive, and IBX is insoluble

• in common organic solvents. To overcome these drawbacks, IBX analogs [12][13][14][15][16][17][18][19][20][21][22] and several iodoxyarene derivatives [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] have been developed, and the stabilization of IBX by combining it with benzoic and

Recent developments in the asymmetric Reformatsky-type reaction

• Hélène Pellissier

Beilstein J. Org. Chem. 2018, 14, 325–344, doi:10.3762/bjoc.14.21

• diastereomeric mixture was further oxidized by treatment with IBX (2-iodoxybenzoic acid) to afford the corresponding chiral ketone 43 as a single diastereomer in 68% yield. Three supplementary steps allowed expected cebulactam A1 to be obtained in 33% yield. The same authors have also applied a related samarium

• mixture of diastereomers (Scheme 18). The latter was subsequently oxidized by treatment with IBX to give ketone 46 as a mixture of two diastereomers (24% de) in 58% yield. After separation, the minor diastereomer was successively converted into (+)-Q-1047H-A-A and (+)-Q-1047H-R-A, allowing the

CF₃SO₂X (X = Na, Cl) as reagents for trifluoromethylation, trifluoromethylsulfenyl-, -sulfinyl- and -sulfonylation. Part 1: Use of CF₃SO₂Na

• Hélène Guyon,
• Hélène Chachignon and
• Dominique Cahard

Beilstein J. Org. Chem. 2017, 13, 2764–2799, doi:10.3762/bjoc.13.272

• by oxidative trifluoromethylation with CF3SO2Na. In that case, 2-iodoxybenzoic acid (IBX) was used as the oxidant to generate the trifluoromethylated radical 22 and atmospheric oxygen was the oxygen source to form the ketone (Scheme 9) [28]. Synthesis of β-trifluoromethyl ketones from cyclopropanols

Mechanochemical synthesis of small organic molecules

• Tapas Kumar Achar,
• Anima Bose and
• Prasenjit Mal

Beilstein J. Org. Chem. 2017, 13, 1907–1931, doi:10.3762/bjoc.13.186

• conditions of energy (Scheme 56) and showed that efficiency under mechanomilling is far better over other methods [58]. Mal and co-workers have addressed the efficiency of 2-iodoxybenzoic acid (IBX) under mechanomilling conditions (Scheme 57) [8]. Generally the major drawback of IBX is its insolubility in

• common organic solvents except DMSO and also its explosive nature at higher temperature [188]. They could overcome these limitations by using IBX under solvent-free mechanomilling conditions. They have demonstrated various oxidation reactions, synthesis of benzimidazoles, deprotection of dithianes, etc

• . The byproduct iodosobenzoic acid (IBA) was recycled over 15 cycles with the help of the oxidant oxone. The economic benefits of IBX under ball milling was also discussed by comparing the literature-known DMSO mediated procedure [8]. The bis(benzotriazolyl)methanethione-assisted thiocarbamoylation of

Oxidative dehydrogenation of C–C and C–N bonds: A convenient approach to access diverse (dihydro)heteroaromatic compounds

• Santanu Hati,
• Ulrike Holzgrabe and
• Subhabrata Sen

Beilstein J. Org. Chem. 2017, 13, 1670–1692, doi:10.3762/bjoc.13.162

• oxidative dehydrogenation, a stoichiometric amount of oxidant is applied in the reaction that gets associated with the nitrogen and facilitates subsequent proton abstraction and elimination in the ring to afford the desired heteroaromatics. Various organic oxidants such as 2-iodoxybenzoic acid (IBX), 2,3

• -dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), KMnO4, transition metal-based oxidants and air have been extensively used to promote this transformation. o-Iodoxybenzoic acid (IBX)-mediated oxidative dehydrogenation IBX was first introduced as an oxidant (in oxidative dehydrogenation) by Nicolaou and co

• -workers in the year 2000 [26][27][28][29]. It oxidizes diverse functionalities such as amines, imines, alcohols etc. [30]. Later, it was demonstrated that IBX can also be used as a reagent for oxidative dehydrogenation of benzylic carbons in various aromatic systems via single electron transfer (SET) and

Effect of uridine protecting groups on the diastereoselectivity of uridine-derived aldehyde 5’-alkynylation

• Raja Ben Othman,
• Mickaël J. Fer,
• Laurent Le Corre,
• Sandrine Calvet-Vitale and
• Christine Gravier-Pelletier

Beilstein J. Org. Chem. 2017, 13, 1533–1541, doi:10.3762/bjoc.13.153

• propargyl alcohols 11–15 (Scheme 2). The aldehydes 6–10 resulting from oxidation with IBX were isolated and directly submitted to Grignard addition without further purification. Grignard reagents were prepared from trimethylsilyl-, triethylsilyl- or triisopropylsilylacetylene and ethylmagnesium bromide in

• derivatives 1–5. To a suspension of protected uridine derivative 1–5 (1 equiv) in acetonitrile (5 × 10−2 M) was added IBX (3 equiv). The suspension was refluxed for 45 min–1.5 h until complete conversion of starting material (TLC). The suspension was cooled to rt, filtered on a celite® pad and the cake was

Towards potential nanoparticle contrast agents: Synthesis of new functionalized PEG bisphosphonates

• Souad Kachbi-Khelfallah,
• Maelle Monteil,
• Margery Cortes-Clerget,
• Evelyne Migianu-Griffoni,
• Jean-Luc Pirat,
• Olivier Gager,
• Julia Deschamp and
• Marc Lecouvey

Beilstein J. Org. Chem. 2016, 12, 1366–1371, doi:10.3762/bjoc.12.130

• one step has been performed. Thus, tested oxidants were the Jones reagent [22], potassium permanganate [23], with catalytic o-iodoxybenzoic acid (IBX) in oxone [24] and catalytic 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) with bis(acetoxy)iodobenzene (BAIB) [25]. The first two conditions led to a

• PEG chain cleavage and the recovery of benzoic acid from alcohol 2. Besides, the mixture IBX/oxone gave the expected product inseparable of IBX byproducts. Only oxidation using TEMPO and BAIB furnished the pure corresponding carboxylic acid. Nevertheless, the low obtained yields encouraged us to test

Stereoselective synthesis of hernandulcin, peroxylippidulcine A, lippidulcines A, B and C and taste evaluation

• Marco G. Rigamonti and
• Francesco G. Gatti

Beilstein J. Org. Chem. 2015, 11, 2117–2124, doi:10.3762/bjoc.11.228

• the final products, we deliberately avoided all toxic selenium based reagents [12][13]. We tested several methodologies and the results are summarized in Table 2. In our initial synthesis [9] we applied the hyperiodine chemistry, developed by Nicolaou. However, the o-iodoxybenzoic acid (IBX) mediated

• oxidation of 8 to give the enone 1 in DMSO at high temperature (80 °C) resulted unsuccessful [24]. The hydrogenation of silyl enol ether derivatives in the presence of the IBX-N-oxide complex gives the corresponding enones, usually with better conversion and under milder conditions (room temperature) [25

• kinetic enol ether 10 in 91% yield ([α]D +19.7° (c 1.4, CHCl3)). The latter was submitted to the oxidative step with the IBX-N-oxide, but even in this case the results were unsatisfactory since only traces of enone 11 were detected. In contrast, the Pd based Saegusa–Larock methodology resulted successful

Preparation of conjugated dienoates with Bestmann ylide: Towards the synthesis of zampanolide and dactylolide using a facile linchpin approach

• Jingjing Wang,
• Samuel Z. Y. Ting and
• Joanne E. Harvey

Beilstein J. Org. Chem. 2015, 11, 1815–1822, doi:10.3762/bjoc.11.197

• Teesdale-Spittle, Rob Keyzers, Peter Northcote, Mark Bartlett and Kalpani Somarathne (VUW). Sophie Geyrhofer prepared and generously supplied IBX. Ian Vorster, Teresa Gen (VUW) and Yinrong Lu (Callaghan Innovation) are thanked for technical support.

Attempts to prepare an all-carbon indigoid system

• Şeref Yildizhan,
• Henning Hopf and
• Peter G. Jones

Beilstein J. Org. Chem. 2015, 11, 363–372, doi:10.3762/bjoc.11.42

• -methylene ketone 12, failed (Dess–Martin reaction, IBX, Swern oxidation etc.); the original plan was to dimerize this intermediate to 4 by, e.g., a McMurry coupling reaction. Also the second route, starting with the reaction of 2-indanone (9) with the Eschenmoser salt 10 according to [17] to give the iodide