Lewis acid-catalyzed Pudovik reaction–phospha-Brook rearrangement sequence to access phosphoric esters

• Jin Yang,
• Dang-Wei Qian and
• Shang-Dong Yang

Beilstein J. Org. Chem. 2022, 18, 1188–1194, doi:10.3762/bjoc.18.123

• with diarylphosphonates and -phosphinates (Scheme 1b). The present method is simple and efficient, providing an extended substrate scope that is complementary to classical similar base-prompted reactions. Results and Discussion We used diphenylphosphine oxide (1a) and 2-pyridinecarboxaldehyde (2a) as

• . Additional experiments were conducted in order to clarify the reaction mechanism. Under standard conditions, only pyridin-2-ylmethyl diphenylphosphinate (3aa) was produced, and the Pudovik adduct (hydroxy(pyridin-2-yl)methyl)diphenylphosphine oxide (4aa) was not detected (Scheme 4a). The control experiment

• of the above results, we concluded that 4aa is the intermediate of this transformation and that Cu(OTf)2 promotes the phospha-Brook rearrangement occurring in the reaction. Based on the above results and literature reports, the proposed mechanism is shown in Scheme 5. First, diphenylphosphine oxide

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

• Ettore Crovini,
• Zhen Zhang,
• Yu Kusakabe,
• Yongxia Ren,
• Yoshimasa Wada,
• Bilal A. Naqvi,
• Prakhar Sahay,
• Tomas Matulaitis,
• Stefan Diesing,
• Ifor D. W. Samuel,
• Wolfgang Brütting,
• Katsuaki Suzuki,
• Hironori Kaji,
• Stefan Bräse and
• Eli Zysman-Colman

Beilstein J. Org. Chem. 2021, 17, 2894–2905, doi:10.3762/bjoc.17.197

• 8.57 μs in 20 wt % DBFPO film (DBFPO = 2,8-bis(diphenylphosphine oxide)dibenzofuran). The device made from this material has a very high EQEmax of 30.3%, which decreases to 18.4% at 1000 cd m−2; the use of a stronger donor in TRZ-TPDICz results in a red-shift of the electroluminescence, compared to

Metal-free synthesis of phosphinoylchroman-4-ones via a radical phosphinoylation–cyclization cascade mediated by K₂S₂O₈

• Qiang Liu,
• Weibang Lu,
• Guanqun Xie and
• Xiaoxia Wang

Beilstein J. Org. Chem. 2020, 16, 1974–1982, doi:10.3762/bjoc.16.164

• afforded the title compounds in moderate yields. Keywords: chroman-4-ones; diphenylphosphine oxide; metal-free; potassium persulfate; radical cyclization; Introduction The chroman-4-one framework is a privileged structural motif found in numerous natural products and pharmaceuticals with extraordinary

•  1a). Besides, in 2016 Li’s group [28] reported a silver-catalyzed straightforward approach for the synthesis of phosphonate-functionalized chroman-4-ones via a phosphoryl radical-initiated cascade cyclization of 2-(allyloxy)arylaldehydes using K2S2O8 as an oxidant, however, diphenylphosphine oxide

• employing 2-(allyloxy)benzaldehyde (1a) and diphenylphosphine oxide (DPPO, 2a) as the model substrates with K2S2O8 as the oxidant, which is a cheap, readily available, and versatile oxidant. On the basis of literature reports [29][30] and our continuing interest in green chemistry [31][32], we set the

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

• [2,3]-sigmatropic rearrangement of an allylic diphenylphosphinite to the diphenylphosphine oxide (Scheme 4) [16]. Diphenylphosphinite 19 was formed in the reaction of allylic alcohol 6 with diphenylphosphine chloride in the presence of DMAP at −20 ºC. The temperature was raised to induce phosphinite’s

• % yield. The allylic diphenylphosphine oxide 21 was subjected to the hydroboration–oxidation reaction introducing stereoselectively the hydroxy group. Hydroboration was carried out with an excess of borane–dimethyl sulfide adduct followed by the oxidation step. The standard C–B bond oxidation protocol

• (H2O2/NaOH) proceeded with the low yield (32%). Application of m-chloroperbenzoic acid (mCPBA) as an oxidant, similarly to Knochels findings [19], gave the higher yield (56%) of (((1R,2R,3R,4R,5R)-4-hydroxypinan-3-yl)methyl)diphenylphosphine oxide (22). Next, phosphine oxide 22 was reduced 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

• -tolyl)- or dibenzylphosphine oxide was carried out in acetonitrile at 100 °C for 1 h affording the products with excellent yields (Scheme 4). Then, (aminomethyl)diphenylphosphine oxide (9) was prepared through debenzylation of (benzylaminomethyl)diphenylphosphine oxide (8, Scheme 5). The reduction was

• carried out in the presence of a 10% palladium on carbon catalyst (Selcat Q), in methanol, at 75 °C for 3 h, and the (aminomethyl)diphenylphosphine oxide (9) was obtained in a yield of 47% after column chromatography. In the next step, (aminomethyl)phosphine oxides 5–7 were converted to bis

Pd-Catalyzed microwave-assisted synthesis of phosphonated 13α-estrones as potential OATP2B1, 17β-HSD1 and/or STS inhibitors

• Rebeka Jójárt,
• Szabolcs Pécsy,
• György Keglevich,
• Mihály Szécsi,
• Réka Rigó,
• Csilla Özvegy-Laczka,
• Gábor Kecskeméti and
• Erzsébet Mernyák

Beilstein J. Org. Chem. 2018, 14, 2838–2845, doi:10.3762/bjoc.14.262

• reacted with diethyl phosphite or diphenylphosphine oxide using Pd(PPh3)4 as catalyst under microwave irradiation. The influence of the new compounds on the transport function of the organic anion transporting polypeptide OATP2B1 was investigated by measuring Cascade Blue uptake. Derivatives bearing a 3

• . Here we disclose the synthesis of novel 2- or 4-substituted 13α-estrone derivatives 8–13 via the Hirao reaction (Scheme 1). Diethyl phosphite (7a) or diphenylphosphine oxide (7b) were chosen as >P(O)H reagents and C–P couplings were planned under microwave irradiation using Pd-based catalysis

• introduction of a large diphenylphosphine oxide moiety onto C-2 improves the binding of the steroid to the enzyme. C-4-substituted 3-OH derivatives 12a and 12b barely suppressed the estrone to 17β-estradiol conversion. The same tendency showed up in our previous works regarding the inhibitory potentials of

Two novel blue phosphorescent host materials containing phenothiazine-5,5-dioxide structure derivatives

• Feng-Ming Xie,
• Qingdong Ou,
• Qiang Zhang,
• Jiang-Kun Zhang,
• Guo-Liang Dai,
• Xin Zhao and
• Huai-Xin Wei

Beilstein J. Org. Chem. 2018, 14, 869–874, doi:10.3762/bjoc.14.73

• lifetime. Carbazole groups are widely used in host materials because of their high triplet energy levels and high hole mobility [15]. The Lee group [16] linked carbazolyl groups to diphenyl phosphoramines to design asymmetric (9-phenyl-9H-carbazole-2,5-diyl)bis(diphenylphosphine oxide) (PCPOs) with a

Recent advances on organic blue thermally activated delayed fluorescence (TADF) emitters for organic light-emitting diodes (OLEDs)

• Thanh-Tuân Bui,
• Fabrice Goubard,
• Malika Ibrahim-Ouali,
• Didier Gigmes and
• Frédéric Dumur

Beilstein J. Org. Chem. 2018, 14, 282–308, doi:10.3762/bjoc.14.18

The synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the microwave-assisted Pudovik reaction

• Erika Bálint,
• Ádám Tajti,
• Anna Ádám,
• István Csontos,
• Konstantin Karaghiosoff,
• Mátyás Czugler,
• Péter Ábrányi-Balogh and
• György Keglevich

Beilstein J. Org. Chem. 2017, 13, 76–86, doi:10.3762/bjoc.13.10

• and α-aryl-α-aminophosphine oxides was synthesized by the microwave-assisted solvent-free addition of dialkyl phosphites and diphenylphosphine oxide, respectively, to imines formed from benzaldehyde derivatives and primary amines. After optimization, the reactivity was mapped, and the fine mechanism

• at all. In the current paper, we wished to develop a facile catalyst and solvent-free MW-assisted method for the synthesis of α-aryl-α-aminophosphonates and α-aryl-α-aminophosphine oxides by the addition of dialkyl phosphites or diphenylphosphine oxide to the double bond of imines, and aimed at the

• aniline at room temperature under solvent-free conditions (Scheme 1). Then, the reaction of N-benzylidene(butyl)amine (1a) with four different dialkyl phosphites and diphenylphosphine oxide was investigated under MW-assisted solvent-free conditions searching for the optimum temperature and reaction time

Microwave-assisted synthesis of (aminomethylene)bisphosphine oxides and (aminomethylene)bisphosphonates by a three-component condensation

• Erika Bálint,
• Ádám Tajti,
• Anna Dzielak,
• Gerhard Hägele and
• György Keglevich

Beilstein J. Org. Chem. 2016, 12, 1493–1502, doi:10.3762/bjoc.12.146

• , triethyl orthoformate and two equivalents of diphenylphosphine oxide. The method is also suitable for the preparation of (aminomethylene)bisphosphonates using (MeO)2P(O)H/(MeO)3CH or (EtO)2P(O)H/(EtO)3CH reactant pairs and even secondary amines. Several intermediates referring to the reaction mechanism

• diphenylphosphine oxide to an isonitrile (Scheme 4b) [36][42]. In this paper, we wish to report the results of our investigations on the synthetic protocol utilizing the three-component condensations of primary or secondary amines, orthoformates and >P(O)H species, such as dialkyl phosphites or diphenylphosphine

• orthoformate, and 2 equivalents of diphenylphosphine oxide at 150 °C for 1 h under MW conditions was studied (Scheme 5). To avoid the formation of by-products, benzylamine was reacted at a lower temperature of 125 °C (Table 1, entry 3). The reactions were carried out without any catalyst and solvent. After

A new method for the synthesis of α-aminoalkylidenebisphosphonates and their asymmetric phosphonyl-phosphinyl and phosphonyl-phosphinoyl analogues

• Anna Kuźnik,
• Roman Mazurkiewicz,
• Mirosława Grymel,
• Katarzyna Zielińska,
• Jakub Adamek,
• Ewa Chmielewska,
• Marta Bochno and
• Sonia Kubica

Beilstein J. Org. Chem. 2015, 11, 1418–1424, doi:10.3762/bjoc.11.153

• of diethyl 2,3-dihydro-4H-1,3-benzoxazin-4-one-2-phosphonate with diphenylphosphine oxide [29] or diphenyltrimethylsilyloxyphosphine [Ph2POSiMe3] [30]. In 2004–2007, Onys’ko et al. reported the synthesis of diethyl or diphenyl 1-(N-phenylsulfonylamino)-1-diphenylphosphinoylmethylphosphonate

• derivatives (Figure 2, 4: R = Ph, R1 = Ar or CCl3, R2 = SO2Ph, R3 = Et or Ph) and diethyl 1-amino-1-diphenylphosphinoyl-2,2,2-trifluoroethylphosphonate (Figure 2, 4: R = Ph, R1 = CF3, R2 = H, R3 = Et) by the addition of diphenylphosphine oxide to the corresponding arylimidoyl-, trichloroacetimidoyl- or

One-pot sequential synthesis of isocyanates and urea derivatives via a microwave-assisted Staudinger–aza-Wittig reaction

• Diego Carnaroglio,
• Katia Martina,
• Giovanni Palmisano,
• Andrea Penoni,
• Claudia Domini and
• Giancarlo Cravotto

Beilstein J. Org. Chem. 2013, 9, 2378–2386, doi:10.3762/bjoc.9.274

• was filtered on a cartridge to remove the polymer-bound diphenylphosphine oxide. The solvent was then evaporated under vacuum, the residue was dissolved in MeOH and Dowex® 50WX8-200 was added. The mixture was stirred at rt for 15 min. Finally, the mixture was filtered on paper and the solvent was

• -bound diphenylphosphine oxide and the residual polymer-bound diphenylphosphine. The solvent was then evaporated under vacuum, the residue was dissolved in MeOH and Dowex® 50WX8-200 was added. The mixture was stirred at rt for 15 min. Finally, the mixture was filtered on paper and the solvent was

Fifty years of oxacalix[3]arenes: A review

• Kevin Cottet,
• Paula M. Marcos and
• Peter J. Cragg

Beilstein J. Org. Chem. 2012, 8, 201–226, doi:10.3762/bjoc.8.22

• reported by Matt in 1999 and was achieved through reaction with NaH and Ph2P(O)CH2OTs in toluene at 90 °C for three days (Scheme 15) [40]. The reaction resulted in the formation of a 4:1 mixture of the cone and partial-cone diphenylphosphine oxide derivatives 25: The preference for the cone formation is