The McKenna reaction – avoiding side reactions in phosphonate deprotection

• Katarzyna Justyna,
• Joanna Małolepsza,
• Damian Kusy,
• Waldemar Maniukiewicz and
• Katarzyna M. Błażewska

Beilstein J. Org. Chem. 2020, 16, 1436–1446, doi:10.3762/bjoc.16.119

• as phosphorus acids and esters are prevailing in nature [3][4], and the compounds found wide applications as therapeutics [5][6], probes [7] or in materials science [8]. The McKenna reaction involves two steps: In the first step an alkyl ester is transformed into the corresponding trimethylsilyl

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Synthesis, antiinflammatory activity, and molecular docking studies of bisphosphonic esters as potential MMP-8 and MMP-9 inhibitors

• Abimelek Cortes-Pacheco,
• María Adelina Jiménez-Arellanes,
• Francisco José Palacios-Can,
• José Antonio Valcarcel-Gamiño,
• Rodrigo Said Razo-Hernández,
• María del Carmen Juárez-Vázquez,
• Adolfo López-Torres and
• Oscar Abelardo Ramírez-Marroquín

Beilstein J. Org. Chem. 2020, 16, 1277–1287, doi:10.3762/bjoc.16.108

• expected, 4–6 could bind the Zn2+ ion in a monodentate fashion through the oxygen atom double bonded to the phosphorus atom (P=O) of one of the phosphonate moieties, as reported in the literature for other structures [38][39]. Only for 3, zinc chelation was observed through the oxygen atom double bonded to

• not aiming directly at the metal ion. However, it can be assumed that because of the flexibility of the protein in solution, the coordination to the metal ion would be possible. The targets 3 and 4 could coordinate the Zn2+ ion through the oxygen atom double bonded to the phosphorus atom (P=O) of one

• kcal/mol and a 3.51 Å O–N distance (Figure 4b). Also, for compound 5, only one hydrogen bond interaction was seen. Indeed, the oxygen atom double bonded to the phosphorus atom of the phosphonate group was strongly bonded to an amide hydrogen atom localized between Ile159 and Leu160, with a 3.08 Å O–N

Fluorinated phenylalanines: synthesis and pharmaceutical applications

• Laila F. Awad and
• Mohammed Salah Ayoup

Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91

• isolation, was carried out with red phosphorus in hydroiodic acid to give the fluorinated phenylalanine analogues 53a–h. Alternatively, a two-step sequence to generate amino acids 53a–h was attempted by first hydrolysis of 52a–h to form acids 54a–h which then were reduced with P/HI to the desired products

Copper-catalysed alkylation of heterocyclic acceptors with organometallic reagents

• Yafei Guo and
• Syuzanna R. Harutyunyan

Beilstein J. Org. Chem. 2020, 16, 1006–1021, doi:10.3762/bjoc.16.90

• -Bu2Zn, respectively). Later, T. Shibata and K. Endo prepared the same product (2c) with a higher enantioselectivity (97% ee) by using the multinuclear phosphorus ligand catalyst L2 [16]. Organoaluminium reagents are also commonly used organometallics in copper-catalysed ACA reactions. For example, in

Pd-catalyzed asymmetric Suzuki–Miyaura coupling reactions for the synthesis of chiral biaryl compounds with a large steric substituent at the 2-position

• Yongsu Li,
• Bendu Pan,
• Xuefeng He,
• Wang Xia,
• Yaqi Zhang,
• Hao Liang,
• Chitreddy V. Subba Reddy,
• Rihui Cao and
• Liqin Qiu

Beilstein J. Org. Chem. 2020, 16, 966–973, doi:10.3762/bjoc.16.85

• unsatisfactorily low (36% ee; Table 1, entry 1). After further examination of the ligands developed by our group (L2–L9), it was found that phosphine ligands with a large steric aryl group linked to a phosphorus atom are more effective than the ligand with a cyclohexyl group both in yield and enantioselectivity

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• amides (Scheme 43) [93]. Singlet oxygen in heteroatom oxidations Singlet oxygen reacts readily with electron pairs of heteroatoms, such as sulfur, selenium, phosphorus, and nitrogen, due to their electrophilicity. The interaction between singlet oxygen and the heteroatom occurs in both physical and

Efficient synthesis of dipeptide analogues of α-fluorinated β-aminophosphonates

• Marcin Kaźmierczak and
• Henryk Koroniak

Beilstein J. Org. Chem. 2020, 16, 756–762, doi:10.3762/bjoc.16.69

• that was proposed based on NMR studies. Keywords: dipeptide analogues; fluorinated aminophosphonates; fluorine; nucleophilic fluorination; phosphorus; Introduction The chemistry of fluorinated aminophosphonates is constantly being developed, mainly due to their wide spectra of applications. What is

Recent advances in Cu-catalyzed C(sp³)–Si and C(sp³)–B bond formation

• Balaram S. Takale,
• Ruchita R. Thakore,
• Elham Etemadi-Davan and
• Bruce H. Lipshutz

Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67

• featuring a 1,4-borylation of α,β-unsaturated compounds 405 was reported by Hosomi in the presence of Cu(OTf)2·C6H6/(t-Bu)3P in DMF. No reaction occurred using (CuOTf)2·C6H6 in the absence of (t-Bu)3P. Mechanistic studies showed that the coordination of phosphorus(III) to Cu(I) accelerated the reaction, as

Rhodium-catalyzed reductive carbonylation of aryl iodides to arylaldehydes with syngas

• Zhenghui Liu,
• Peng Wang,
• Zhenzhong Yan,
• Suqing Chen,
• Dongkun Yu,
• Xinhui Zhao and
• Tiancheng Mu

Beilstein J. Org. Chem. 2020, 16, 645–656, doi:10.3762/bjoc.16.61

• )2, Rh(acac)(CO)2, [RhCl(COD)]2, Rh(MeCN)2(COD)BF4, Rh(COD)BF4, Rh(COD)2OTf, [Rh(OMe)(COD)]2, Rh(OAc)2, [Rh(CF3COO)]2, [Rh(CH3(CH2)6CO2)2]2, Rh(acac)3, Rh(ethylene)2(acac), [Rh(ethylene)2Cl]2, Rh(norbornadiene)2BF4, [Cp*RhCl2]2, Rh/C, and RhCl3·3H2O), ligands containing nitrogen or phosphorus (PP3

Copper-catalyzed O-alkenylation of phosphonates

• Nuria Vázquez-Galiñanes,
• Mariña Andón-Rodríguez,
• Patricia Gómez-Roibás and
• Martín Fañanás-Mastral

Beilstein J. Org. Chem. 2020, 16, 611–615, doi:10.3762/bjoc.16.56

• subject to selectivity problems, involve toxic and hazardous materials or are limited to the restricted availability of the corresponding phosphorus reagents. Therefore, the development of alternative methods for the synthesis of acyclic enol phosphonates is highly desirable. Diaryliodonium and aryl

A systematic review on silica-, carbon-, and magnetic materials-supported copper species as efficient heterogeneous nanocatalysts in “click” reactions

• Pezhman Shiri and
• Jasem Aboonajmi

Beilstein J. Org. Chem. 2020, 16, 551–586, doi:10.3762/bjoc.16.52

• suitable ligands [14]. Ligands serve to increase and modulate the reactivity of copper salts. In the first attempt, tris((1-benzyl-1H-1,2,3-triazol-4-yl)methyl)amine (TBTA) considerably speds up the copper-catalyzed cyclization [15]. Many structurally diverse ligands, such as nitrogen-, phosphorus-, carbon

Synthesis of triphenylene-fused phosphole oxides via C–H functionalizations

• Md. Shafiqur Rahman and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2020, 16, 524–529, doi:10.3762/bjoc.16.48

• nature as hybrids of triphenylene and benzo[b]phosphole. Keywords: C–H functionalization; fluorescence; phosphole; polycyclic aromatic hydrocarbons; triphenylene; Introduction The phosphorus-containing five-membered ring, phosphole, has attracted significant attention as a structural motif in π

• -conjugated functional molecules [1][2][3][4][5][6][7][8][9]. Its inherently unique electronic structure, along with opportunities to modify the phosphorus center and the periphery by substitution or ring fusion, have stimulated chemists to explore a structurally diverse range of phosphole derivatives with

• extended π-system. These included, in particular, those fused with polycyclic aromatic hydrocarbons (PAHs) for possible applications in organic electronics, bioimaging and sensing, and asymmetric catalysis (Figure 1). To name a few examples, Yamaguchi et al. described synthetic routes to novel phosphorus

Architecture and synthesis of P,N-heterocyclic phosphine ligands

• Wisdom A. Munzeiwa,
• Bernard Omondi and
• Vincent O. Nyamori

Beilstein J. Org. Chem. 2020, 16, 362–383, doi:10.3762/bjoc.16.35

• coordination [12]. Thus, their use in catalysis is the basis of this review article with the main focus on the synthesis of N-heterocyclic phosphines. The presence of soft donor atoms such as phosphorus results in the formation of hemilabile ligands. These are multidentate ligands having hard P-donor and soft

• occurs selectively on the end opposite to the phosphorus donor atom [48]. This is because the position trans to the heteroatom, with greater π-acceptor character, is more electrophilic than the one opposite the σ-donor atom [9]. One can modify this electronic imbalance by attaching vicinal heteroatoms

• . The π-acceptor character of phosphorus can be reinforced by the presence of oxygen and/or nitrogen whilst σ-donating potency of nitrogen can be manipulated by switching between sp3 and sp2 hybridization [9][49][50]. The synthesis of phosphines is quite delicate because when exposed to air, some of

Synthesis, liquid crystalline behaviour and structure–property relationships of 1,3-bis(5-substituted-1,3,4-oxadiazol-2-yl)benzenes

• Afef Mabrouki,
• Malek Fouzai,
• Armand Soldera,
• Abdelkader Kriaa and
• Ahmed Hedhli

Beilstein J. Org. Chem. 2020, 16, 149–158, doi:10.3762/bjoc.16.17

• acids in the presence of phosphorus oxychloride according to standard methods [29], oxadiazole derivatives 2 were obtained (Scheme 1). On the other hand, we converted compound 1 into sulfanyloxadiazole derivatives 4 by treatment with carbon disulfide and subsequent alkylation of the obtained

[1,3]/[1,4]-Sulfur atom migration in β-hydroxyalkylphosphine sulfides

• Katarzyna Włodarczyk,
• Piotr Borowski and
• Marek Stankevič

Beilstein J. Org. Chem. 2020, 16, 88–105, doi:10.3762/bjoc.16.11

• Marie Curie-Skłodowska Sq., 20-031 Lublin, Poland 10.3762/bjoc.16.11 Abstract β-Hydroxyalkylphosphine sulfides undergo [1,3]- or [1,4]-sulfur atom phosphorus-to-carbon migration in the presence of Lewis or Brønsted acids. The direction of sulfur atom migration depends on the type of acid used for the

• ketophosphonates from vinylphosphates [53]. [1,4]-Rearrangements include that of o-phosphorus-substituted benzyl carbanions [34], phosphorus group migration in O-phosphorylated 1,4-benzodiazepines [54], or phosphoryl group carbon-to-oxygen transfer [55]. The common feature of every rearrangement presented above is

• the cleavage of one single bond between phosphorus and either carbon or oxygen atom, while the multiple bond remains intact. Herein, we present the results concerning an unusual transformation of β-hydroxyalkylphosphine sulfides, which undergo [1,3]- or [1,4]-rearrangement in the presence of an acid

Synthesis of C-glycosyl phosphonate derivatives of 4-amino-4-deoxy-α-ʟ-arabinose

• Lukáš Kerner and
• Paul Kosma

Beilstein J. Org. Chem. 2020, 16, 9–14, doi:10.3762/bjoc.16.2

• have frequently been exploited as potential inhibitors for glycosyl transferases since the carbon–phosphorus bond is not hydrolyzed in the active site of glycosyl transferases [10][11][12][13]. Herein, we report on the synthesis of α-anomeric C-arabinosyl methylphosphonate ester derivatives as model

• carbon atom as well as signals of two upfield-shifted deoxy protons at 2.72 and 2.55 ppm, respectively, to the anomeric carbon atom. In addition, for compound 10, lacking the conjugation to the phosphorus atom, a significant downfield shift of the 31P NMR signal was observed (17.97 ppm in 10 versus 10.95

• 14 as the minor isomer in 17% yield. The HPLC-based purification step even allowed for further separation of the diastereomers on phosphorus of both compounds. Selective methyl ester cleavage of 12 and 14 – again using NaI in a minimum volume of acetone – was straightforward and furnished the octyl

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• synthesized chiral compounds based on phosphorus esters and investigated their effects as chiral auxiliaries in the α-alkylation of secondary amines via anodic oxidation [100]. The constant current methoxylation of N-protected chiral pyrrolidines 173 in an undivided cell resulted in 174 in excellent yield

1,5-Phosphonium betaines from N-triflylpropiolamides, triphenylphosphane, and active methylene compounds

• Vito A. Fiore,
• Chiara Freisler and
• Gerhard Maas

Beilstein J. Org. Chem. 2019, 15, 2603–2611, doi:10.3762/bjoc.15.253

• bonding situation in annelated oxaphospholes 8 (Scheme 7) is best described by the contribution of two canonical structures: an oxaphosphole 8A with a pentacovalent phosphorus atom and a P–O bond, and a betaine structure 8B with a phosphonium group and a P···O distance that varies with the electronic

• III (Scheme 1) (PR3 = PMe2Ph, R’ = Ph, 2.597 and 2.620 Å in two symmetry-independent molecules [15]). Furthermore, the coordination around the phosphorus atom comes close to a trigonal-pyramidal geometry with the oxygen and the carbon atom C13 in apical positions: the angle O···P–C13 is 177.1° and the

• sum of bond angles involving atoms C1, C19 and C25 in the equatorial plane is 346.8o (compared to 328.4° for an ideal tetrahedral coordination). All these data point to the description of Z-3e as a 1,5-betaine with an attractive electrostatic interaction of phosphorus and oxygen. The 31P NMR chemical

Chiral terpene auxiliaries V: Synthesis of new chiral γ-hydroxyphosphine oxides derived from α-pinene

• Anna Kmieciak and
• Marek P. Krzemiński

Beilstein J. Org. Chem. 2019, 15, 2493–2499, doi:10.3762/bjoc.15.242

• site providing a trans relationship between the hydroxy and the phosphine substituents. Keywords: isopinocamphone; monoterpenes; phosphines; [2,3]-sigmatropic rearrangement; verbanone; Introduction Chiral phosphorus compounds, despite many years of research, still enjoy unflagging interest of many

• research groups [1]. Compounds with a phosphorus atom attached to a stereogenic carbon center in acyclic and cyclic structures play an important role as chiral ligands in transition metal complexes [2]. They were applied to various catalytic asymmetric reactions [3][4], such as hydrogenations [3][4][5][6

Fluorescent phosphorus dendrimers excited by two photons: synthesis, two-photon absorption properties and biological uses

• Anne-Marie Caminade,
• Artem Zibarov,
• Eduardo Cueto Diaz,
• Aurélien Hameau,
• Maxime Klausen,
• Kathleen Moineau-Chane Ching,
• Jean-Pierre Majoral,
• Jean-Baptiste Verlhac,
• Olivier Mongin and
• Mireille Blanchard-Desce

Beilstein J. Org. Chem. 2019, 15, 2287–2303, doi:10.3762/bjoc.15.221

• Different types of two-photon absorbing (TPA) fluorophores have been synthesized and specifically functionalized to be incorporated in the structure of phosphorus dendrimers (highly branched macromolecules). The TPA fluorophores were included in the periphery as terminal functions, in the core, or in the

• the mechanism of action of anticancer compounds, and for safer photodynamic therapy. Keywords: bioimaging; dendrimer; fluorescence; phosphorus; two-photon absorption; Introduction Natural luminescence phenomena such as the bioluminescence of fireflies or of certain marine microorganisms, or the

• enhancement of TPA responses [17][18][19][20][21]. Phosphorus-containing dendrimers [22], mainly of the phosphorhydrazone type [23], stand out among all the other types of dendrimers by their properties [24], in particular in biology [25][26] and their highly modular structure [27]. Indeed, different types of

Synthesis of ([1,2,4]triazolo[4,3-a]pyridin-3-ylmethyl)phosphonates and their benzo derivatives via 5-exo-dig cyclization

• Aleksandr S. Krylov,
• Artem A. Petrosian,
• Julia L. Piterskaya,
• Nataly I. Svintsitskaya and
• Albina V. Dogadina

Beilstein J. Org. Chem. 2019, 15, 1563–1568, doi:10.3762/bjoc.15.159

• ]thiadiazole [2], and benzo[4,5]imidazo[2,1-b]thiazole [3], as well as due to the simultaneous presence of a biologically active phosphorus function in the molecules. Recently, we have shown that the reaction of chloroethynylphosphonates with 2-aminopyridines proceeds through a 5-endo-dig cyclization to form

• one method for the formation of a [1,2,4]triazolo[4,3-a]pyridine ring with participation of an acetylene triple bond; an oxidative cyclization during the reaction of terminal phenylacetylenes with 2-hydrazinylpyridines [14]. However, data on phosphorus-containing triazolopyridines are scarce, although

• . Chemical shifts of the phosphorus nucleus for compounds 3–8 were registered in the range of δP 22–23 and 18–19 ppm for dimethyl а and diisopropyl phosphonates b, respectively. In the 1Н NMR spectra of products 3–8, the methylene unit was recorded as a doublet signal (δH 3.42–4.19 ppm) with a spin–spin

Different reactivity of phosphorylallenes under the action of Brønsted or Lewis acids: a crucial role of involvement of the P=O group in intra- or intermolecular interactions at the formation of cationic intermediates

• Stanislav V. Lozovskiy,
• Alexander Yu. Ivanov and
• Aleksander V. Vasilyev

Beilstein J. Org. Chem. 2019, 15, 1491–1504, doi:10.3762/bjoc.15.151

• phosphonic acids and other phosphorus-containing compounds. Contrary to Brønsted acids, 3-methylbuta-1,2-dien-1-ylphosphonic dichloride [Cl2(O=)P–HC=C=CMe2] reacted with the Lewis acid AlCl3 in an intermolecular way forming noncyclic intermediates, which were investigated by NMR spectroscopy and DFT

• substituents at the phosphorus atom of phosphorylallenes [13][14][15][16]. These cations were intermediates in Brønsted and Lewis acid-promoted intramolecular reactions of phosphorus-containing allenes with aromatic π-nucleophiles giving rise to various (bi)cyclic phosphorus-containing compounds [13][14][15

• species E1 (δ 53 ppm) and E2 (δ 43 ppm). This difference may reveal that phosphorus in cation E4 is bound to a carbon atom, rather than to a heteroatom O or N, like in E1 and E2. Structurally close six-membered ring cations, having the C–P bond, resonate at 30.5–31.9 in 31P NMR [16], that is close to the

Microwave-assisted synthesis of N,N-bis(phosphinoylmethyl)amines and N,N,N-tris(phosphinoylmethyl)amines bearing different substituents on the phosphorus atoms

• Erika Bálint,
• Anna Tripolszky,
• László Hegedűs and
• György Keglevich

Beilstein J. Org. Chem. 2019, 15, 469–473, doi:10.3762/bjoc.15.40

• phosphorus atoms was synthesized by the microwave-assisted and catalyst-free Kabachnik–Fields reaction of (aminomethyl)phosphine oxides with paraformaldehyde and diphenylphosphine oxide. The three-component condensation of N,N-bis(phosphinoylmethyl)amine, paraformaldehyde and a secondary phosphine oxide

• now. In this paper, we report the efficient, catalyst-free and MW-assisted synthesis of N,N-bis(phosphinoylmethyl)amine and N,N,N-tris(phosphinoylmethyl)amine derivatives bearing different substituents on the phosphorus atoms. Results and Discussion Synthesis of N,N-bis(phosphinoylmethyl)alkylamines

• containing different substituents on the phosphorus atoms First, the (aminomethyl)phosphine oxide starting materials 5–7 were synthesized following our previous protocol [11]. Thus, the MW-assisted Kabachnik–Fields reaction of primary amines (butyl-, cyclohexyl- or benzylamine), paraformaldehyde and di(p

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• is most commonly modified to generate the phosphorylated derivative of NR+, nicotinamide mononucleotide, NMN. The phosphorylation is achieved by reacting NR+ in its salt form with phosphorus oxychloride in trimethyl phosphate resulting, after hydrolysis, in NMN (Scheme 17). Lee et al. [27] carefully

• group and – after quenching with water – to give NMN analogues with one alkoxy group at the phosphorus atom. The resulting compounds were purified by column chromatography on an aminopropyl-modified silica gel Quadrasil AP column to yield the pure NMN analogues in low to moderate yields (8–40%). The

• patent publication of Sauve et al. [59] divulges phosphorylation of isopro-NR+ 29 (as triflate salt) with phosphorus oxychloride in trimethyl phosphate at 0 °C for 48 h to give isopro-NMN 33 in 80% yield (Scheme 18) after silica gel column chromatography using a 6:4 DCM/MeOH mixture as an eluent