Synthesis and characterization of water-soluble C₆₀–peptide conjugates

• Yue Ma,
• Lorenzo Persi and
• Yoko Yamakoshi

Beilstein J. Org. Chem. 2024, 20, 777–786, doi:10.3762/bjoc.20.71

• measured by the ESR spin trapping method under irradiation of visible light (527 nm green LED). 4-Oxo-TEMP was used as a spin trapping reagent to form an adduct with 1O2, i.e., 4-oxo-TEMPO, which was observed by ESR (Figure 7b). As shown in Figure 7a, upon visible light irradiation, three peaks

• s, number of scans: 1. b) Scheme for the photoinduced 1O2 generation by C60 and reaction with spin trapping reagent 4-oxo-TEMP to form 4-oxo-TEMPO. Supporting Information Supporting Information File 4: Details for the synthesis of 5a–c and intermediates as well as spectral data. Acknowledgements

Photoredox catalysis harvesting multiple photon or electrochemical energies

• Mattia Lepori,
• Simon Schmid and
• Joshua P. Barham

Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81

• products (e.g., 7) whereas irradiation with blue light (λ = 455 nm) provided disubstituted products 8 (Figure 5A). Additionally, adding a different trapping reagent before switching from green to blue light allows for a sequential and controlled substitution in a one-pot reaction (Figure 5B). 2,4,6

• the single electron reduction of aryl halides while simultaneously generating S4•−. Upon C(sp2)–X bond cleavage, an aryl radical is formed and trapped by a trapping reagent such as N-methylpyrrole, yielding the open-shell species 4•. Upon irradiation of S3•−, the excited species *[S3•−] oxidizes 4• to

Cathodic generation of reactive (phenylthio)difluoromethyl species and its reactions: mechanistic aspects and synthetic applications

• Sadanobu Iwase,
• Shinsuke Inagi and
• Toshio Fuchigami

Beilstein J. Org. Chem. 2022, 18, 872–880, doi:10.3762/bjoc.18.88

• , and dihydrofuran. The results are summarized in Table 1. Regardless of trapping reagents, 1.3–1.4 F/mol of electricity was required to consume the starting material 1. The required electricity was similar to the electrolysis in the absence of the trapping reagent. Only when α-methylstyrene was used as

• the radical trapping reagent, the expected radical adduct 4 was formed in reasonable yield of ca. 30% (Table 1, run 1). A platinum cathode is more suitable for the formation of adduct 4 compared to a glassy carbon cathode (Table 1, run 2). Dolbier et al. reported that electron-poor perfluoroalkyl

• significantly. In this case, the required electricity was increased to 1.8 F/mol. From these results, we anticipate that a one-electron reduction of compound 1 takes place to generate the PhSCF2 radical, which is further reduced affording the PhSCF2 anion when a trapping reagent is absent. The resulting anion

Iron-catalyzed domino coupling reactions of π-systems

• Austin Pounder and
• William Tam

Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196

Silver-catalyzed synthesis of β-fluorovinylphosphonates by phosphonofluorination of aromatic alkynes

• Yajing Zhang,
• Qingshan Tian,
• Guozhu Zhang and
• Dayong Zhang

Beilstein J. Org. Chem. 2020, 16, 3086–3092, doi:10.3762/bjoc.16.258

• extremely low yield. Another H-phosphonate, namely dimethyl phosphite, was a suitable substrate for this transformation and provided the products 3 in good yield (Scheme 3). The well-known radical-trapping reagent 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO) was used to gain an insight into the reaction

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

Construction of trisubstituted chromone skeletons carrying electron-withdrawing groups via PhIO-mediated dehydrogenation and its application to the synthesis of frutinone A

• Qiao Li,
• Chen Zhuang,
• Donghua Wang,
• Wei Zhang,
• Rongxuan Jia,
• Fengxia Sun,
• Yilin Zhang and
• Yunfei Du

Beilstein J. Org. Chem. 2019, 15, 2958–2965, doi:10.3762/bjoc.15.291

• absence of a carbonyl group in its chemical structure [85]. Control experiments were designed and conducted to elucidate the reaction mechanism of this transformation. When 3 equiv of TEMPO, a radical-trapping reagent, were added to the reaction mixture, product 2a was obtained in 55% yield (Scheme 3

• , method a). When another radical-trapping reagent, BHT, was used, the reaction gave 50% yield of the desired product 2a (Scheme 3, method b). Since the reaction was not greatly suppressed in both cases, we tentatively propose that this dehydrogenative oxidation reaction may undergo both radical and

Copper(I)-catalyzed tandem reaction: synthesis of 1,4-disubstituted 1,2,3-triazoles from alkyl diacyl peroxides, azidotrimethylsilane, and alkynes

• Muhammad Israr,
• Changqing Ye,
• Munira Taj Muhammad,
• Yajun Li and
• Hongli Bao

Beilstein J. Org. Chem. 2018, 14, 2916–2922, doi:10.3762/bjoc.14.270

• trapping reagent (tetramethylpiperdinyloxy, TEMPO) [38][39] to the standard reaction system, no product 3a was obtained; only the radical trapped product 4 was detected by GC–MS (Scheme 4a). To further investigate this phenomenon, we synthesized a substrate bearing a cyclopropylmethyl moiety, diacyl

Three-component coupling of aryl iodides, allenes, and aldehydes catalyzed by a Co/Cr-hybrid catalyst

• Kimihiro Komeyama,
• Shunsuke Sakiyama,
• Kento Iwashita,
• Itaru Osaka and
• Ken Takaki

Beilstein J. Org. Chem. 2018, 14, 1413–1420, doi:10.3762/bjoc.14.118

• coupling reaction between iodobenzene (1a), 5-phenylpenta-1,2-diene (2a), and 4-methylbenzaldehyde (3a) in the presence of CoBr2 (10 mol %), CrCl3 (20 mol %), and manganese powder (2.0 equiv), using trimethylsilyl chloride (TMSCl, 1.2 equiv) as a trapping reagent [7]. These results are summarized in Table

Preparation and isolation of isobenzofuran

• Morten K. Peters and
• Rainer Herges

Beilstein J. Org. Chem. 2017, 13, 2659–2662, doi:10.3762/bjoc.13.263

• laboratory scale with high yields, from affordable, commercially available starting materials. Keywords: [4 + 2] cycloaddition; Diels–Alder; isobenzofuran; trapping reagent; Introduction Isobenzofurans have been described as the most reactive dienes for Diels–Alder reactions [1][2][3][4][5]. Their high

• + 8] and [4 + 6] additions [7][8][9][10]. Highly strained alkenes and alkynes have been trapped with isobenzofurans. 1,3-Diphenylisobenzofuran is the preferred trapping reagent for singlet oxygen and is used to quantify the generation of 1O2 in photodynamic therapy [4][11]. The most important

Dialkyl dicyanofumarates and dicyanomaleates as versatile building blocks for synthetic organic chemistry and mechanistic studies

• Grzegorz Mlostoń and
• Heinz Heimgartner

Beilstein J. Org. Chem. 2017, 13, 2235–2251, doi:10.3762/bjoc.13.221

• leading to a zwitterionic intermediate 57, which is trapped by morpholine to give the adduct 58. The latter eliminates HCN and converts to enamine 56. The postulated pathway was supported by a similar experiment, in which methanol replaced morpholine as a trapping reagent [58][59]. An interesting

• observation was made when less nucleophilic anilines were used as trapping agents. The formation of adducts of type 56 proceeds in competition with the trapping reaction by a second molecule of 55 leading to the homologue enamine 59 [60]. Finally, reactions performed with 55 in the absence of any trapping

• reagent yielded 1-azabicyclo[2.1.1]hexanes 60 as products of an intramolecular cyclization of the intermediate zwitterion 57. In all cases, these products were obtained as mixtures of cis-and trans-stereoisomers in favor of the trans-isomer [59][61]. Another class of nucleophilic reagents used for

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

• yields (Scheme 33). The reaction yield were lowered by adding a radical-trapping reagent, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), indicating that radical HO·, which was generated from TBHP, may participate in the oxidation of the palladium complex from Pd(II) to Pd(IV). In 2016, Guin and co-workers

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

• is consistent with our previous report [19], which discloses that the alkylation of the C–C double bond initiates the radical process. Furthermore, a radical-trapping reagent, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), was added to the reaction, and the reaction was completely inhibited, affording

• -unprotected substrate 8a; b) reaction with the addition of radical-trapping reagent TEMPO; c) KIE study. Proposed mechanism. Optimization of typical reaction conditions.a Supporting Information Supporting Information File 254: Experimental details and spectral data. Acknowledgements We gratefully

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

High chemoselectivity in the phenol synthesis

• Matthias Rudolph,
• Melissa Q. McCreery,
• Wolfgang Frey and
• A. Stephen K. Hashmi

Beilstein J. Org. Chem. 2011, 7, 794–801, doi:10.3762/bjoc.7.90

• ketone as potential trapping reagent Next we decided to use a carbonyl group as the competing unit. The intermediate G, formed from substrate 16, would offer the option of competition of the phenol synthesis (Scheme 7, pathway a) to yield 18, and reaction with the second carbonyl group (Scheme 7, pathway

• the TBS group was observed (38, Figure 5). Intramolecular alcohol as potential trapping reagent For the interception of intermediate A we also considered the option of an intramolecular hydroxy nucleophile, compound 39 (Scheme 10) would represent this type of substrate. The intermediate I would be an