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

• %) 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

• ). Prolongation of the reaction time to 24 h led to a slight decrease in the yield of 3aa (Table 1, entry 3) due to its instability under the reaction conditions. The possibility of using iodide salts (NaI and TBAI) was shown in Entries 8 and 9, however, the yield of 3aa in that cases is lower than in the case of

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

• 5a was obtained in 70% yield (Table 1, entry 7). Interestingly, no traces of the diiodo compound were observed even if the hypervalent iodine(III) reagent was slowly added. Transposing the previously optimized bromo(trifluoro)acetoxylation conditions but using TBAI instead of KI did not improve the

• yield and reaction times and excess reagents were required to reach completion (Table 1, entry 8). Using directly 1.5 equivalents of both PIFA and TBAI did not suffice to improve the yield, whether in acetonitrile or in dichloromethane (Table 1, entries 9 and 10). When chlorination was attempted with a

Bromide-assisted chemoselective Heck reaction of 3-bromoindazoles under high-speed ball-milling conditions: synthesis of axitinib

• Jingbo Yu,
• Zikun Hong,
• Xinjie Yang,
• Yu Jiang,
• Zhijiang Jiang and
• Weike Su

Beilstein J. Org. Chem. 2018, 14, 786–795, doi:10.3762/bjoc.14.66

• . Currently, the Heck reaction is usually carried out by adding an excess of phase-transfer catalyst such as tetrabutylammonium bromide (TBAB) or tetrabutylammonium iodide (TBAI) to increase the reaction yield under both solvent-heating [19][20][21][22][23] and solvent-free conditions [24][25][26][27

• , TBAI or tetrabutylammonium chloride (TBAC) did not provide a satisfactory result (Table S1, entries 3 and 4). It was interesting to find that using bromide salts (LiBr, NaBr, KBr and TBAB) as additives, not only the conversion rate of 1a was increased, but also the side-product 4a was suppressed

One-pot preparation of 4-aryl-3-bromocoumarins from 4-aryl-2-propynoic acids with diaryliodonium salts, TBAB, and Na₂S₂O₈

• Teppei Sasaki,
• Katsuhiko Moriyama and
• Hideo Togo

Beilstein J. Org. Chem. 2018, 14, 345–353, doi:10.3762/bjoc.14.22

• mixture of 1,2-dichloroethane (DCE) and water at 90 °C was carried out to give 3-bromo-4-phenylcoumarin (3Aa) in 68% yield (Table 2, entry 7). When the iodocyclization of phenyl ester 2Aa with tetrabutylammonium iodide (TBAI, 2.0 equiv)/Na2S2O8 (1.5 equiv) was carried out, the yield of iodocyclization

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• in situ intramolecular cyclization of 5-aminopyrazole-4-caroxylate 35 with β-haloaldehydes 36 via the corresponding imine derivative was carried out in presence of Pd(PPh3)2Cl2 (1.0 mol %), Cu2O (1.0 mol %), 1,10-phenanthroline (2.0 mol %), TBAI (6 mol %), by Batra et al. [50] to generate 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

Synthesis of ergostane-type brassinosteroids with modifications in ring A

• Vladimir N. Zhabinskii,
• Darya A. Osiyuk,
• Yuri V. Ermolovich,
• Natalia M. Chaschina,
• Tatsiana S. Dalidovich,
• Miroslav Strnad and
• Vladimir A. Khripach

Beilstein J. Org. Chem. 2017, 13, 2326–2331, doi:10.3762/bjoc.13.229

• , NaI, DMF, 150 °C (83%); (c) KOH, MeOH, 65 °C (96%). (a) MCPBA, CH2Cl2, 20 °C (90%); (b) NBS, DME, 20 °C; (c) KOH, MeOH, 20 °C (85% over 2 steps). (a) BnBr, DMAP, Bu2SnO, TBAI, DIPEA, 110 °C (94%); (b) PCC, CH2Cl2, 20 °C (84%); (c) H2, Pd/C, 20 °C (99%); (d) NaBH4, EtOH, −25 °C (61%); (e) KOH, MeOH, 65

• °C (96%). (a) TsCl, DMAP, Py, 30 °C (91%); (b) Py, 115 °C (65%); (c) KOH, MeOH, 20 °C (52%). (a) NaBH4, EtOH, −25 °C (49%); (b) KOH, MeOH, 65 °C (85%). (a) Anisaldehyde, TMSCl, MeOH, 20 °C; (b) BnBr, DMAP, Bu2SnO, TBAI, DIPEA, 110 °C (86% over 2 steps); (c) PCC, CH2Cl2, 20 °C (81%); (d) H2, Pd/C, 20

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

• . Mal and co-workers reported a metal free, solvent-free and room temperature synthesis of amide bonds at 62–75% yield under ball-milling (21 Hz) from aromatic aldehydes and N-chloramine in presence of 20 mol % of tetrabutylammonium iodide (TBAI) and 2.0 equiv of TBHP (Scheme 16) [79]. Aromatic

The chemistry and biology of mycolactones

• Matthias Gehringer and
• Karl-Heinz Altmann

Beilstein J. Org. Chem. 2017, 13, 1596–1660, doi:10.3762/bjoc.13.159

Transition-metal-catalyzed synthesis of phenols and aryl thiols

• Yajun Liu,
• Shasha Liu and
• Yan Xiao

Beilstein J. Org. Chem. 2017, 13, 589–611, doi:10.3762/bjoc.13.58

• stoichiometric amount of Cu(OAc)2 in the presence of Ag2CO3 and TBAI as additives in DMF at 100 °C (Scheme 26). Notably, their protocol was so efficient that the reactions could accomplish within 1 hour. The substrate scope showed benzamides bearing both electron-donating groups and electron-withdrawing groups

Nucleophilic displacement reactions of 5′-derivatised nucleosides in a vibration ball mill

• Olga Eguaogie,
• Patrick F. Conlon,
• Francesco Ravalico,
• Jamie S. T. Sweet,
• Thomas B. Elder,
• Louis P. Conway,
• Marc E. Lennon,
• David R. W. Hodgson and
• Joseph S. Vyle

Beilstein J. Org. Chem. 2017, 13, 87–92, doi:10.3762/bjoc.13.11

• following addition of NaI (500, 50 or 5 mol %) or TBAI (50 or 5 mol %). Following the successful application of VBM using a thiolate nucleophile, we were prompted to explore related reactions of alkylselenols. However, the sensitivity of such compounds towards aerial oxidation meant that, in our hands, an

• ) remained untransformed during (dry) VBM or liquid-assisted grinding (LAG) in the presence of DMF with excess KSeCN (3 equiv). As found previously, the addition of catalytic TBAI (vide supra) did not alter this outcome nor did the use of a larger excess (5 equiv) of selenocyanate. The addition of DMF to the

New approaches to organocatalysis based on C–H and C–X bonding for electrophilic substrate activation

• Pavel Nagorny and
• Zhankui Sun

Beilstein J. Org. Chem. 2016, 12, 2834–2848, doi:10.3762/bjoc.12.283

• atoms covalently bonded to a benzylic carbon (Scheme 8). In 2016 Maruoka and Shirakawa followed up the aforementioned studies by demonstrating that tetraalkylammonium salts L5, L6, L11 and L12 as well as TBAI could activate imines toward aza-Diels–Alder reaction with Danishefsky’s diene (Scheme 9) [51

Efficient syntheses of climate relevant isoprene nitrates and (1R,5S)-(−)-myrtenol nitrate

• Sean P. Bew,
• Glyn D. Hiatt-Gipson,
• Graham P. Mills and
• Claire E. Reeves

Beilstein J. Org. Chem. 2016, 12, 1081–1095, doi:10.3762/bjoc.12.103

• with bromoacetone was a requirement for an efficient ‘bromide to nitrate’ substitution. Changing tactics we opted to generate the more reactive iodoacetone in situ from chloroacetone (42) and a stoichiometric quantity of tetra-n-butylammonium iodide (TBAI). Gratifyingly the iodoacetone reacted readily

• further 16 hours, the majority of (E)-60 had reacted as judged by TLC and 1H NMR analysis. Removing the sodium chloride via a simple filtration was more advantageous than the previously employed organic soluble and more expensive TBAI (Scheme 6). Straightforward flash-column purification afforded (E)-10

Synthesis, antimicrobial and cytotoxicity evaluation of new cholesterol congeners

• Mohamed Ramadan El Sayed Aly,
• Hosam Ali Saad and
• Shams Hashim Abdel-Hafez

Beilstein J. Org. Chem. 2015, 11, 1922–1932, doi:10.3762/bjoc.11.208

• : (a) Propargyl bromide, NaH, Et2O/DMF (quant. for both 26 and 30); (b) 3, CuSO4·5H2O, L-AsAc, THF/H2O (89% for 27 and 74% for 31); (c) H2, Pd/C 10%, MeOH. A: Ring A of the lactose moiety, B: Ring B of the lactose moiety. Reagents and conditions: (a) Bu2SnO, MeOH; propargyl bromide, TBAI, Tol (92%); (b

Multivalent polyglycerol supported imidazolidin-4-one organocatalysts for enantioselective Friedel–Crafts alkylations

• Tommaso Pecchioli,
• Manoj Kumar Muthyala,
• Rainer Haag and
• Mathias Christmann

Beilstein J. Org. Chem. 2015, 11, 730–738, doi:10.3762/bjoc.11.83

• ), NaH (1.1 equiv), 6-chloro-1-hexyne (1.3 equiv), TBAI (0.01 equiv), DMF, 25 °C, 16 h, 88%. Initial screening on the Friedel–Crafts alkylation of N-methylpyrrole (11) with trans-cinnamaldehyde (12).a Influence of temperature in the Friedel–Crafts alkylation.a Catalyst loading study.a Dilution

Synthesis of carbohydrate-scaffolded thymine glycoconjugates to organize multivalency

• Anna K. Ciuk and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2015, 11, 668–674, doi:10.3762/bjoc.11.75

• optimized procedure employing DBU and TBAI at rt [5] over two days to deliver the protected glycothymine derivative 12 in 64% yield. The acetyl protecting groups were cleaved employing Zemplén’s procedure [30]. During work-up with acidic ionic exchange resin, surprisingly cleavage of the isopropylidene

Synthesis of the furo[2,3-b]chromene ring system of hyperaspindols A and B

• Danielle L. Paterson and
• David Barker

Beilstein J. Org. Chem. 2015, 11, 265–270, doi:10.3762/bjoc.11.29

• -methylenedioxybenzene and t-butyllithium) to give ketone 17 in 84% yield (Scheme 2). Allylation of ketone 17 proved problematic with the use of strong bases such as LDA and LiHMDS, giving none of the desired product. However, the use of allyl bromide and NaH in the presence of TBAI, in THF at reflux, gave the desired

• h, 14%. Reagents and conditions: (i) H3C(CH3O)NH·HCl, n-BuLi, THF, −78 °C, 4 h, 81%; (ii) 1-bromo-3,4-methylenedioxybenzene, t-BuLi, THF, −78 °C, 3 h, 84%; (iii) NaH, allyl bromide, TBAI, THF, 65 °C, 20 h, 95%; (iv) ethylene glycol, pTSA, toluene, reflux, 16 h, 44%; (v) OsO4, NMO, t-BuOH, H2O, THF

Relay cross metathesis reactions of vinylphosphonates

• Raj K. Malla,
• Jeremy N. Ridenour and
• Christopher D. Spilling

Beilstein J. Org. Chem. 2014, 10, 1933–1941, doi:10.3762/bjoc.10.201

• ) failed to react at all with methyl acrylate under similar conditions, even with higher catalyst loading and extended reaction times. Initially, the synthesis of the allyl vinylphosphonate esters was achieved using a transesterification reaction catalysed by tetra n-butylammonium iodide (TBAI) (Scheme 5

• ) [28]. A solution of the vinylphosphonate 12b, 1.1 equivalents of allyl bromide and 5 mol % TBAI in toluene was heated at reflux for 7 hours to give a 53% conversion to both the mono- and diallyl vinylphosphonates 14a and 14b in a 10:1 ratio. The overall conversion could be improved with excess allyl

• bromide, increasing the amount of TBAI and prolonged heating times, either at reflux or in a microwave reactor. The ratio of di- to mono-allyl phosphonate esters increases with the duration of reaction. A subsequent reaction of vinylphosphonate 12b employing 5 equivalents of allyl bromide, 5 mol % TBAI

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• TBAB (tetrabutylammonium bromide), TBAI (tetrabutylammonium iodide), TMAC (tetramethylammonium chloride) or 18-crown-6. The best result was obtained with TBAB and 18-crown-6 catalysts in a CH2Cl2/water or AcOEt/water mixture (yields included from 72 to 85%). The carbamate anion is another nucleophilic

Synthesis of new enantiopure poly(hydroxy)aminooxepanes as building blocks for multivalent carbohydrate mimetics

• Léa Bouché,
• Maja Kandziora and
• Hans-Ulrich Reissig

Beilstein J. Org. Chem. 2014, 10, 213–223, doi:10.3762/bjoc.10.17

• of the carbonyl group and deprotection. Conditions: a) NaBH4, EtOH, 0 °C, 40 min to 16 h; b) TBAF (1 M THF), THF, 0 °C, 10 min to 3.5 h. [TBAF = tetra-n-butylammonium fluoride] Synthesis of propargylic ether 18. Conditions: a) propargyl bromide, NaOH, TBAI, H2O/CH2Cl2, −20 °C → rt, 7 d; b) NaBH4

• , EtOH, 0 °C, 4 h; c) TBAF (1 M THF), THF, 0 °C → rt, 3 d. [TBAI = tetra-n-butylammonium iodide] Synthesis of tricyclic compound 20, bicyclic azide 24 and bicyclic amine 25. Conditions: a) MsCl, Et3N, CH2Cl2, 0 °C → rt, 5 h; b) NaBH4, EtOH, 0 °C, 6 to 16 h; c) NaN3, DMF, reflux, 16 to 46 h; d) Et3N, DMF

Enantioselective synthesis of planar chiral ferrocenes via palladium-catalyzed annulation with diarylethynes

• Yan-Chao Shi,
• Rong-Fei Yang,
• De-Wei Gao and
• Shu-Li You

Beilstein J. Org. Chem. 2013, 9, 1891–1896, doi:10.3762/bjoc.9.222

• details, see Supporting Information File 1). Lowering the reaction temperature to 60 °C, excellent enantioselectivity (97% ee) could be obtained, but with a decreased yield as the starting material was not fully consumed (entry 12, Table 1). When TBACl (entry 14, Table 1) or TBAI (entry 15, Table 1) was

Synthesis of mucin-type O-glycan probes as aminopropyl glycosides

• David Benito-Alifonso,
• Rachel A. Jones,
• Anh-Tuan Tran,
• Hannah Woodward,
• Nichola Smith and
• M. Carmen Galan

Beilstein J. Org. Chem. 2013, 9, 1867–1872, doi:10.3762/bjoc.9.218

• % overall yield. The sequence involved temporary protection of the free hydroxy at C-3 by reaction with acetic anhydride and pyridine, SN2 displacement of the chloride in monosaccharide 9 with n-tetrabutylammonium iodide (n–TBAI) in refluxing acetonitrile followed by the addition of NaN3. Ester removal was

Iron-catalyzed decarboxylative alkenylation of cycloalkanes with arylvinyl carboxylic acids via a radical process

• Jincan Zhao,
• Hong Fang,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2013, 9, 1718–1723, doi:10.3762/bjoc.9.197

• reactions. Additionally, metal-free methodologies, which use TBHP, PhI(OAc)2, TBAI, I2 or Lewis/Brønsted acids, have also been employed for cross-dehydrogenative coupling reactions [48][49][50][51][52][53][54][55][56][57]. Owing to the general low reactivity of cycloalkane C(sp3)–H bonds, the direct

Glycosylation efficiencies on different solid supports using a hydrogenolysis-labile linker

• Mayeul Collot,
• Steffen Eller,
• Markus Weishaupt and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2013, 9, 97–105, doi:10.3762/bjoc.9.13

• functionalized with linker 1 (Scheme 4). Coupling to both chloro-functionalized Merrifield resin 16 and Jandajel 17 was achieved by a tetrabutylammonium iodide (TBAI) mediated substitution in the presence of Cs2CO3. Capping of unreacted chlorides by cesium acetate and subsequent acidic hydrolysis of the THP

• 2 steps; (f) TFA, DCM, rt, 99%; (g) NHS, DCC, DMAP, CH3CN, DCM, rt, 63%; (h) 2 M aq NaOH, THF, 55 °C, 92%; (i) p-TsOH·H2O, MeOH, DCM, rt, 94%; (j) Pd(OAc)2, HCOONH4, MeOH, H2O, 90%. Coupling of linker 1 to different resins. Reactions and conditions: (a) 1. 1 and 16 or 17, Cs2CO3, DMF, TBAI, 60 °C; 2

• . CsOAc, TBAI, DMF, 60 °C; 3. p-TsOH·H2O, MeOH, DCM, rt; (b) 1. 1 and 18, 19, 20, 21 or 22, HOBt, DIC, DMF, rt; 2. Ac2O, pyridine, DCM, rt; 3. p-TsOH·H2O, MeOH, DCM, rt; (c) 1. 2 and 18, 19, 20 or 22, pyridine, DCM, rt; 2. Ac2O, pyridine, DCM, rt; 3. 1, Cs2CO3, DMF, TBAI, 60 °C; 4. CsOAc, TBAI, DMF, 60 °C

Acylsulfonamide safety-catch linker: promise and limitations for solid–phase oligosaccharide synthesis

• Jian Yin,
• Steffen Eller,
• Mayeul Collot and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 2067–2071, doi:10.3762/bjoc.8.232

• -TsOH·H2O, DCM, 86%; (g) LiOH·H2O, THF/H2O, reflux, 95%; (h) 4-sulfamoylbenzoic acid, DCC, DMAP, DCM/DMF, 60%. Functionalization of different resins. Reagents and conditions: (a) Cs2CO3, DMF, TBAI, Merrifield chloride resin; (b) CsOAc, DMF, TBAI; (c) p-TsOH·H2O, MeOH; (d) DIC, HOBt, DCM, Merrifield amine

• resin; (e) Ac2O, pyridine; (f) (COCl)2, DMF (cat), 99%; (g) TentaGel amine resin, DCM, pyridine, then Ac2O; (h) 10, Cs2CO3, DMF, TBAI. Glycosylation and cleavage reactions for analysis. Reagents and conditions: (a) automated glycosylations using 17, 18 or 19; (b) NaOMe, MeOH. Further investigations of