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

Cross-dehydrogenative coupling for the intermolecular C–O bond formation

• Igor B. Krylov,
• Vera A. Vil’ and
• Alexander O. Terent’ev

Beilstein J. Org. Chem. 2015, 11, 92–146, doi:10.3762/bjoc.11.13

• oxidative C–O coupling of alcohols and aldehydes 161–164 with N-hydroxysuccinimide (154a) was performed in the presence of (diacetoxyiodo)benzene [147] or iodoxybenzoic acid (IBX) [148] as the oxidant. The authors hypothesized that the reaction proceeds via the nucleophilic addition of N-hydroxysuccinimide

• (diacetoxyiodo)benzene, and these compounds were subjected, without isolation, in the reaction with amines to prepare amides. The reaction was performed at room temperature with N-hydroxysuccinimide (154a) taken in an equivalent amount or a small excess relative to aldehyde. Iodoxybenzoic acid (IBX) or the Co

NAA-modified DNA oligonucleotides with zwitterionic backbones: stereoselective synthesis of A–T phosphoramidite building blocks

• Boris Schmidtgall,
• Claudia Höbartner and
• Christian Ducho

Beilstein J. Org. Chem. 2015, 11, 50–60, doi:10.3762/bjoc.11.8

• yield of the desired 5'-alcohols 15 and 16 was limited though by partial concomitant cleavage of the 3'-O-TBDMS group upon prolonged reaction times. Alcohols 15 and 16 were then oxidized to aldehydes 10 and 11 in quantitative yields using IBX in refluxing acetonitrile [50]. With respect to their limited

Synthesis and bioactivity of analogues of the marine antibiotic tropodithietic acid

• Patrick Rabe,
• Tim A. Klapschinski,
• Nelson L. Brock,
• Christian A. Citron,
• Paul D’Alvise,
• Lone Gram and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2014, 10, 1796–1801, doi:10.3762/bjoc.10.188

• treated under various oxidation conditions (including DDQ, IBX, SeO2, and MnO2) to install the tropone moiety by dehydrogenation, but unfortunately all these reaction conditions failed. Compound 22 was subsequently converted into the free acid 23 by treatment with TFA, while similar conversions of 20 and

Total synthesis of (+)-grandiamide D, dasyclamide and gigantamide A from a Baylis–Hillman adduct: A unified biomimetic approach

• Andivelu Ilangovan and
• Shanmugasundar Saravanakumar

Beilstein J. Org. Chem. 2014, 10, 127–133, doi:10.3762/bjoc.10.9

• clearly demonstrated that IBX (Table 1, entry 5) is the best reagent to get the aldehyde 27 in better yield and quality. After analyzing the products obtained from the oxidation with PCC (Table 1, entry 4), we found that the reaction produced gigantamide A (7) along with the aldehyde 27. We have also

Halogenated volatiles from the fungus Geniculosporium and the actinomycete Streptomyces chartreusis

• Tao Wang,
• Patrick Rabe,
• Christian A. Citron and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2013, 9, 2767–2777, doi:10.3762/bjoc.9.311

• starting material for the preparation of the oxidising agents IBX and DMP. A contamination of a bacterial agar plate with traces of 2-iodobenzoic acid was assumed as a possible, albeit unlikely explanation for the formation of 23 in the bacterial cultures. In our laboratories all analytical work is

Garner’s aldehyde as a versatile intermediate in the synthesis of enantiopure natural products

• Mikko Passiniemi and
• Ari M.P. Koskinen

Beilstein J. Org. Chem. 2013, 9, 2641–2659, doi:10.3762/bjoc.9.300

• reduction can be used. The ester can be reduced to alcohol 6 (e.g., with NaBH4/LiCl) and then oxidized to 1 with non-basic methods (e.g., IBX/DMP [30] or TEMPO/NaOCl [31] to name a few), which will not epimerize the α-center. For our synthesis of 1, we adopted a slightly modified sequence [32]. L-Serine (2

An organocatalytic route to 2-heteroarylmethylene decorated N-arylpyrroles

• Alexandre Jean,
• Jérôme Blanchet,
• Jacques Rouden,
• Jacques Maddaluno and
• Michaël De Paolis

Beilstein J. Org. Chem. 2013, 9, 1480–1486, doi:10.3762/bjoc.9.168

• bis(aryl)methylene position with CAN has been reported [29], this is the first example of bis(heteroaryl)methylene oxidation employing this reagent [30]. In order to increase the local electron deficiency of the scaffold, 9a was oxidized with 2-iodoxybenzoic acid (IBX) into ketone 10a (98%), which

• dichloromethane were used for this work. Following our procedure [13], catalyst 6 was prepared from (±)-1-benzyl-3-aminopyrrolidine [18471-40-4]. N-Arylimino ethyl glyoxylates 2a–c were prepared by a condensation of ethyl glyoxylate and arylamines in toluene (c = 1 M) with MgSO4 at room temperature. IBX (2

• -pyrrole-2-carboxylate (10a): A solution of 9a (26 mg, 0.0593 mmol) in AcOEt (0.6 mL) was treated with IBX (50 mg, 0.178 mmol, 3 equiv). The suspension was stirred at 80 °C for 4 h before being brought to rt and filtered. Evaporation of the volatile led to analytically pure 10a which can be further

Hypervalent iodine/TEMPO-mediated oxidation in flow systems: a fast and efficient protocol for alcohol oxidation

• Nida Ambreen,
• Ravi Kumar and
• Thomas Wirth

Beilstein J. Org. Chem. 2013, 9, 1437–1442, doi:10.3762/bjoc.9.162

• [4][5][6]. Hypervalent iodine compounds in general have emerged as versatile oxidizing agents with compounds such as DMP (Dess–Martin periodinane) and IBX finding regular utility as highly selective oxidizing agents [7][8][9]. The use of the nitroxyl radical TEMPO (2,2,6,6-tetramethylpiperidine-1

Synthesis of the tetracyclic core of Illicium sesquiterpenes using an organocatalyzed asymmetric Robinson annulation

• Lynnie Trzoss,
• Jing Xu,
• Michelle H. Lacoske and
• Emmanuel A. Theodorakis

Beilstein J. Org. Chem. 2013, 9, 1135–1140, doi:10.3762/bjoc.9.126

• the corresponding C-6/C-14 diol motif. Selective TBS protection of the C-14 primary alcohol followed by an IBX oxidation of the C-6 secondary alcohol yielded ketone 19 in 80% combined yield over three steps. Triflation of the C-6 ketone with McMurry’s reagent (PhNTf2) [83][84][85][86] followed by a Pd

The crystal structure of the Dess–Martin periodinane

• Albert Schröckeneder,
• Desiree Stichnoth,
• Peter Mayer and
• Dirk Trauner

Beilstein J. Org. Chem. 2012, 8, 1523–1527, doi:10.3762/bjoc.8.172

• usually prepared from 2-iodobenzoic acid (2) in a two-step procedure, which involves oxidation with Oxone (a formulation of peroxomonosulfate) [5], followed by heating of the intermediary iodine(V) species IBX (3) with acetic anhydride and catalytic amounts of p-toluenesulfonic acid [6]. Upon repeating

• decades ago [7] and that the X-ray structure of IBX (3) was also known [8]. Browsing the Cambridge Crystallographic Data Centre, however, we were surprised to find that no X-ray structure of 1 itself has been published to date. We thus set out to investigate a range of crystallization conditions to obtain

• to rotate along the acetate C–C bonds to best fit the experimental electron density. CCDC 866010. 1-Hydroxy-1,2-benziodoxol-3(1H)-one (IBX) (3): 2-iodobenzoic acid (100 g, 403 mmol) was added to a solution of Oxone (2KHSO5/KHSO4/K2SO4) (322 g, 524 mmol) in water (2 L) and stirred at 80 °C for 4 h

Directed aromatic functionalization in natural-product synthesis: Fredericamycin A, nothapodytine B, and topopyrones B and D

• Charles Dylan Turner and
• Marco A. Ciufolini

Beilstein J. Org. Chem. 2011, 7, 1475–1485, doi:10.3762/bjoc.7.171

• , desilylation of 69 (TBAF) furnished an alcohol that, contrary to the parent 69 or other TIPS-protected synthetic intermediates, exhibited no atropisomerism (single compound by 1H and 13C NMR). Oxidation (IBX) and treatment of the emerging ketone 74 with 48% aqueous HBr in AcOH under reflux afforded synthetic

Multicomponent reaction access to complex quinolines via oxidation of the Povarov adducts

• Esther Vicente-García,
• Rosario Ramón,
• Sara Preciado and
• Rodolfo Lavilla

Beilstein J. Org. Chem. 2011, 7, 980–987, doi:10.3762/bjoc.7.110

• corresponding fused quinolines, avoiding elimination by-products. After unsuccessful attempts using palladium on carbon (decomposition), CuCl (partial oxidative elimination), Fremy’s salt (unreactive) and IBX (a complex reaction leading to unknown compounds), we focused our attention on MnO2 as the oxidant of