DABCO- and DBU-promoted one-pot reaction of N-sulfonyl ketimines with Morita–Baylis–Hillman carbonates: a sequential approach to (2-hydroxyaryl)nicotinate derivatives

• Soumitra Guin,
• Raman Gupta,
• Debashis Majee and
• Sampak Samanta

Beilstein J. Org. Chem. 2018, 14, 2771–2778, doi:10.3762/bjoc.14.254

• as the requirement of high temperatures or use of strong oxidants (H2O2, oxone, K2S2O8, TBHP, PIDA, NHPI etc.) that are not much compatible with functionality, precluding late-stage functionalization. Moreover, the scope of substitution on the pyridine ring is limited which in turn hampers the

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

• addition–cyclization reactions of aryl 2-alkynoates with RC(=O)CO2H/AgNO3(cat.)/K2S2O8 at 60 °C [24], with Cu(OAc)2/1-trifluoromethyl-3,3-dimethyl-1,2-benziodoxole (Togni reagent) at 60 °C [25], with R2P(=O)H/Ag2CO3(cat.)/Mg(NO3)2 at 100 °C [26], with BrCF2CO2Et/fac-Ir(ppy)3(cat.) under irradiation at rt

• [27], with R-CH=O/(n-Bu)4NBr (TBAB, cat.)/K2S2O8 at 90 °C [28], with ArSO2H/Eosin Y(cat.)/tert-butyl hydrogen peroxide (TBHP) at rt [29], and with ArSO2NHNH2/n-Bu4NI(cat.)/TBHP at 80 °C [30]. In addition, the formation of coumarins via the bromine-radical-mediated reaction of aryl 2-alkynoates with

• TBAB/K2S2O8 at 90 °C [31], the cyanomethyl-radical-mediated reaction of aryl 2-alkynoates with tert-butyl peroxybenzoate (TBPB)/acetonitrile at 130 °C [32], the sunlight-promoted reaction of aryl 2-alkynoates with N-iodosuccinimide (NIS) at rt [33], and the visible-light-mediated reaction of aryl 2

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

• CF3SO2Na by means of an oxidative system comprising catalytic amounts of silver(I) nitrate and potassium persulfate K2S2O8. Both atmospheric oxygen and K2S2O8 can be the source of the oxygen atom of the ketone moiety. A series of experiments that include the formation of TEMPO–CF3 (TEMPO: 2,2,6,6

• using 18O2; no reaction occurred under N2 instead of O2; K2S2O8 rather than O2 served as initiator; the radical CF3SO2• could either extrude SO2 to CF3• or react with O2 to re-initiate the radical chain process (Scheme 7). Vinyl azides were used by Liu and co-workers as precursors of α

• reactions with K2S2O8, I2O5 or a hypervalent iodine reagent, and (iii) photochemical activation. Most of the works concerned cascade intramolecular reactions in which a C–C bond is formed after the initial trifluoromethylation. Therefore, Lipshutz and co-workers reported a copper-catalysed intramolecular

Chemoselective synthesis of diaryl disulfides via a visible light-mediated coupling of arenediazonium tetrafluoroborates and CS₂

• Jing Leng,
• Shi-Meng Wang and
• Hua-Li Qin

Beilstein J. Org. Chem. 2017, 13, 903–909, doi:10.3762/bjoc.13.91

• undesired diphenyl polysulfides (Table 2, entry 4). Switching to DMSO as the solvent for the reaction afforded exclusively the desired product 3a in excellent yield (88%, Table 2, entry 6). Next, other sulfur sources were also examined, such as S8, NaSH, Na2S, Na2S2O3, Na2S2O4 and K2S2O8, however, none of

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

• ]. Rao and co-workers found that both biaryl ketone and aryl alkyl ketones could be regioselectively hydroxylated in satisfying yields. The reaction proceeded in TFA/TFAA in the presence of Pd(OAc)2 as catalyst and several type of oxidants including selectfluor, PhI(OAc)2 and K2S2O8, respectively (Scheme

• reaction conditions for the hydroxylation of aryl alkyl ketones. The conditions using PhI(TFA)2 as oxidant and DCE as the solvent were milder and more selective, while the conditions using K2S2O8 as oxidant and TFA as solvent were more reactive (Scheme 42). Interestingly, although the reaction gave the

• ketones. The Rao group developed a catalytic system of [RuCl2(p-cymene)]2 and K2S2O8 in TFA/TFAA, which promoted the hydroxylation of ethyl benzoates, benzamides and carbamates (Scheme 49). They reported the first ortho-hydroxylation of ethyl benzoates in 2012 [79]. Both electron-rich and electron

Cascade alkylarylation of substituted N-allylbenzamides for the construction of dihydroisoquinolin-1(2H)-ones and isoquinoline-1,3(2H,4H)-diones

• Ping Qian,
• Bingnan Du,
• Wei Jiao,
• Haibo Mei,
• Jianlin Han and
• Yi Pan

Beilstein J. Org. Chem. 2016, 12, 301–308, doi:10.3762/bjoc.12.32

• -methylallyl)benzamide (4a) and cyclohexane (2a) as model compounds (Table 1). As shown in Table 1, we found that the reactions did not happen or gave only a trace amount of the desired product with K2S2O8, AIBN, BPO and TBHP as oxidants (Table 1, entries 1, 3–5). PhI(OAc)2 and DCP could be used as oxidants

Determination of formation constants and structural characterization of cyclodextrin inclusion complexes with two phenolic isomers: carvacrol and thymol

• Miriana Kfoury,
• David Landy,
• Steven Ruellan,
• Lizette Auezova,
• Hélène Greige-Gerges and
• Sophie Fourmentin

Beilstein J. Org. Chem. 2016, 12, 29–42, doi:10.3762/bjoc.12.5

• complexes could be used in food formulations as flavoring and antioxidant agents. Experimental Materials Carvacrol (1), thymol (2), Trolox and K2S2O8 were purchased from Aldrich. Methyl orange (MO) was purchased from Acros Organics. CRYSMEB (DS = 4.9) was provided from Roquette Frères (Lestrem, France), α

• state. The ABTS•+ was generated by reacting the ABTS salt (7 mM) with K2S2O8 (2.45 mM) in water at room temperature in the dark for 12–16 h. A diluted ABTS•+ solution was then prepared in water to obtain an initial absorbance of 0.75 ± 0.2 at 730 nm using an UV–visible dual-beam spectrophotometer

Pd(OAc)₂-catalyzed dehydrogenative C–H activation: An expedient synthesis of uracil-annulated β-carbolinones

• Biplab Mondal,
• Somjit Hazra,
• Tarun K. Panda and
• Brindaban Roy

Beilstein J. Org. Chem. 2015, 11, 1360–1366, doi:10.3762/bjoc.11.146

• % yield of 5a with 52% conversion of starting material. Increasing the temperature to 90 °C (Table 1, entry 2) afforded 63% yield of 5a with 80% conversion of 4a. Then different oxidants [Cu(OTf)2, PhI(OAc)2, K2S2O8, (NH4)2S2O8, p-benzoquinone (BQ), oxone, AgOAc, molecular oxygen] were examined under

• with Cu(OAc)2 (Table 1, entry 7). The use of K2S2O8 increased the yield of 5a to 83% (Table 1, entry 5) with complete conversion of starting material; AgOAc further increased the yield to 91% (Table 1, entry 9). Molecular oxygen also used as an oxidant resulted in a low 30% yield of 5a (Table 1, entry

Metal-free one-pot synthesis of 2-substituted and 2,3-disubstituted morpholines from aziridines

• Hongnan Sun,
• Binbin Huang,
• Run Lin,
• Chao Yang and
• Wujiong Xia

Beilstein J. Org. Chem. 2015, 11, 524–529, doi:10.3762/bjoc.11.59

• observed as the only ring-opening product. After screening different persulfates, in concordance with Zeng [32], we found that ammonium persulfate ((NH4)2S2O8) is superior to Na2S2O8 and K2S2O8 in the transformation, leading to chloroethoxyamine 2a in an excellent yield (93%) in short time. Encouraged by

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

Synthesis of ethoxy dibenzooxaphosphorin oxides through palladium-catalyzed C(sp²)–H activation/C–O formation

• Seohyun Shin,
• Dongjin Kang,
• Woo Hyung Jeon and
• Phil Ho Lee

Beilstein J. Org. Chem. 2014, 10, 1220–1227, doi:10.3762/bjoc.10.120

• )arylphosphonates by using L-Selectride (Scheme 2). The C–H activation/C–O formation of 2-(phenyl)phenylphosphonic acid monoethyl ester (1a) was examined with a variety of oxidants and bases in the presence of Pd(OAc)2. A multitude of oxidants such as K2S2O8, BQ, benzoyl peroxide, PhI(TFA)2, Cu(OAc)2, CuCl2, CuBr

An easy direct arylation of 5-pyrazolones

• Hao Gong,
• Yiwen Yang,
• Zechao Wang and
• Chunxiang Kuang

Beilstein J. Org. Chem. 2013, 9, 2033–2039, doi:10.3762/bjoc.9.240

• ). When the reaction was under oxygen (1 atm) in a sealed tube and oxygen was used as an oxidant, product 3a was obtained in 55% yield (Table 1, entry 17). Changing the oxidant to K2S2O8, benzoquinone and Cu(OAc)2 decreased the yield to 5%, 0% and 25%, respectively (Table 1, entries 18–20). When Ag2CO3

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

• , Fe2O3 and Fe3O4 tested (Table 1, entries 4–8). Application of other oxidants such as K2S2O8, H2O2 (30% aqueous solution) or TBPB did not afford any improvements (Table 1, entries 9–11). A decreased loading of Fe(acac)3 to 10 mol % or an increased amount of DTBP to 5.0 equiv and a lower temperature (110