Hydrogenation of unactivated enamines to tertiary amines: rhodium complexes of fluorinated phosphines give marked improvements in catalytic activity

• Sergey Tin,
• Tamara Fanjul and
• Matthew L. Clarke

Beilstein J. Org. Chem. 2015, 11, 622–627, doi:10.3762/bjoc.11.70

• Abstract In the hydrogenation of sluggish unactivated enamine substrates, Rh complexes of electron-deficient phosphines are demonstrated to be far more reactive catalysts than those derived from triphenylphosphine. These operate at low catalyst loadings (down to 0.01 mol %) and are able to reduce

• enhance the rate of Rh catalysed hydrogenation relative to more electron donating ligands such as triphenylphosphine. The hydrogenation of enamine 1e at a S/Rh ratio of 250 at 65 °C proceeded at a suitable rate, such that simply measuring conversion at the times given provides a meaningful measure of the

• relative rates of hydrogenation for Rh catalysts derived from electron-donating and electron-withdrawing ligands. A screen of monodentate ligands was performed for hydrogenation of 1e with catalysts derived from ligands 4–9 (Scheme 3). Compared to triphenylphosphine, more electron-poor ligands

The Shono-type electroorganic oxidation of unfunctionalised amides. Carbon–carbon bond formation via electrogenerated N-acyliminium ions

• Alan M. Jones and
• Craig E. Banks

Beilstein J. Org. Chem. 2014, 10, 3056–3072, doi:10.3762/bjoc.10.323

• (Fmol−1) was required [20]. The authors also detail a deallylation and a debenzylation deprotection method to 108. An alternative strategy to chiral amino acids was demonstrated by Kuźnik and colleagues [98] through the electrochemical preparation of 3-triphenylphosphine-2,5-piperazinediones as chiral

First chemoenzymatic stereodivergent synthesis of both enantiomers of promethazine and ethopropazine

• Paweł Borowiecki,
• Daniel Paprocki and
• Maciej Dranka

Beilstein J. Org. Chem. 2014, 10, 3038–3055, doi:10.3762/bjoc.10.322

• (96% ee) despite using the same procedure as for the reaction between (S)-(+)-5 and PBr3. In addition, bromination of (S)-(+)-5 under Appel reaction conditions employing tetrabromomethane (CBr4) as a halide ion source used along with triphenylphosphine (Ph3P) was also investigated. Although this

(2R,1'S,2'R)- and (2S,1'S,2'R)-3-[2-Mono(di,tri)fluoromethylcyclopropyl]alanines and their incorporation into hormaomycin analogues

• Armin de Meijere,
• Sergei I. Kozhushkov,
• Dmitrii S. Yufit,
• Christian Grosse,
• Marcel Kaiser and
• Vitaly A. Raev

Beilstein J. Org. Chem. 2014, 10, 2844–2857, doi:10.3762/bjoc.10.302

• %, respectively). Upon treatment with the iodine/triphenylphosphine reagent in the presence of imidazole, the racemic trans-(2-fluoromethylcyclopropyl)methanols 25a–c were smoothly converted to the corresponding iodides 11a–c in very good yields (Scheme 3). Alkylation of the glycine equivalent enolates derived

Synthesis of the pentasaccharide repeating unit of the O-antigen of E. coli O117:K98:H4

• Pintu Kumar Mandal

Beilstein J. Org. Chem. 2014, 10, 2724–2728, doi:10.3762/bjoc.10.287

• out by treatment with triphenylphosphine [33], then the product was acetylated using acetic anhydride and pyridine to give disaccharide derivative 13 in 84% overall yield in two steps. The anomeric PMP group of compound 13 was oxidatively cleaved using ceric(IV) ammonium nitrate (CAN) [15] and the

Versatile synthesis of amino acid functionalized nucleosides via a domino carboxamidation reaction

• Vicky Gheerardijn,
• Jos Van den Begin and
• Annemieke Madder

Beilstein J. Org. Chem. 2014, 10, 2566–2572, doi:10.3762/bjoc.10.268

• protected serine to deliver product 6 in good yield and purity after recrystallization in cold diethyl ether (64%) [63]. Coupling of protected serine methyl ester 6 with TBDMS-protected nucleoside 1 in the presence of tetrakis(triphenylphosphine)palladium(0) and Et3N in THF under CO atmosphere (4 bar) gave

Synthesis of aromatic glycoconjugates. Building blocks for the construction of combinatorial glycopeptide libraries

• Markus Nörrlinger and
• Thomas Ziegler

Beilstein J. Org. Chem. 2014, 10, 2453–2460, doi:10.3762/bjoc.10.256

• nitro group was achieved with a Staudinger reaction [14]. Thus, treatment of 5 with triphenylphosphine in aqueous THF gave tert-butyl 3-aminomethyl-5-nitrobenzoate which was not isolated but immediately converted into the corresponding Fmoc-protected derivative 6 in 78% overall yield. Final

Visible light photoredox-catalyzed deoxygenation of alcohols

• Daniel Rackl,
• Viktor Kais,
• Peter Kreitmeier and
• Oliver Reiser

Beilstein J. Org. Chem. 2014, 10, 2157–2165, doi:10.3762/bjoc.10.223

• triphenylphosphine to triphenylphospine oxide and iodine to iodide, are required, which appears to be problematic for establishing a sustainable protocol that allows the recycling and reuse of the reagents involved. Herein we report a redox economic deoxygenation method of alcohols in which formation of radicals is

The effect of permodified cyclodextrins encapsulation on the photophysical properties of a polyfluorene with randomly distributed electron-donor and rotaxane electron-acceptor units

• Aurica Farcas,
• Ana-Maria Resmerita,
• Pierre-Henri Aubert,
• Flavian Farcas,
• Iuliana Stoica and
• Anton Airinei

Beilstein J. Org. Chem. 2014, 10, 2145–2156, doi:10.3762/bjoc.10.222

• these compounds for polymer light-emitting layers and photovoltaic applications are currently underway and will be reported in due course. Experimental Materials and methods 9,9-dioctylfluorene-2,7-bis(trimethyleneborate) (3), 2,7-dibromofluoren-9-one, tetrakis(triphenylphosphine) palladium(0) [Pd(PPh3

Organophosphorus chemistry

• Paul R. Hanson

Beilstein J. Org. Chem. 2014, 10, 2087–2088, doi:10.3762/bjoc.10.217

• phosphinoyl-indoles and phosphinoyl-isocoumarins and new chemistries of H-phosphonates. The Thematic Series also details work on new metathesis-based reactions of vinyl phosphonates and phosphate tethers, novel phosphorus-based ligands in asymmetric catalysis, novel rasta resin–triphenylphosphine oxides and

Pd/C-catalyzed aerobic oxidative esterification of alcohols and aldehydes: a highly efficient microwave-assisted green protocol

• Marina Caporaso,
• Giancarlo Cravotto,
• Spyros Georgakopoulos,
• George Heropoulos,
• Katia Martina and
• Silvia Tagliapietra

Beilstein J. Org. Chem. 2014, 10, 1454–1461, doi:10.3762/bjoc.10.149

• triphenylphosphine to the reaction mixture (Table 1, entry 5) only had minimal effects on substrate conversion and selectivity. Preliminary sonication of the K2CO3 in methanol, prior to adding the catalyst and the substrate, led to a significant increase in reactivity affording complete conversion and complete

Streptopyridines, volatile pyridine alkaloids produced by Streptomyces sp. FORM5

• Ulrike Groenhagen,
• Michael Maczka,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2014, 10, 1421–1432, doi:10.3762/bjoc.10.146

• synthesis of crotyltriphenylphosphonium bromide (18). Crotyl bromide (17, 2.23 g, 16.52 mmol) was added to a mixture of triphenylphosphine (3.67 g, 14 mmol) in THF and stirred under reflux overnight. THF was removed under reduced pressure and the resulting solid was dissolved in a mixture of CH2Cl2/MeOH (10

Rasta resin–triphenylphosphine oxides and their use as recyclable heterogeneous reagent precursors in halogenation reactions

• Xuanshu Xia and
• Patrick H. Toy

Beilstein J. Org. Chem. 2014, 10, 1397–1405, doi:10.3762/bjoc.10.143

• Xuanshu Xia Patrick H. Toy Department of Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong, People’s Republic of China 10.3762/bjoc.10.143 Abstract Heterogeneous polymer-supported triphenylphosphine oxides based on the rasta resin architecture have been synthesized, and applied as

• reagent precursors in a wide range of halogenation reactions. The rasta resin–triphenylphosphine oxides were reacted with either oxalyl chloride or oxalyl bromide to form the corresponding halophosphonium salts, and these in turn were reacted with alcohols, aldehydes, aziridines and epoxides to form

• halogenated products in high yields after simple purification. The polymer-supported triphenylphosphine oxides formed as a byproduct during these reactions could be recovered and reused numerous times with no appreciable decrease in reactivity. Keywords: Appel reaction; halogenation; organophosphorus

Synthesis, characterization and DNA interaction studies of new triptycene derivatives

• Sourav Chakraborty,
• Snehasish Mondal,
• Rina Kumari,
• Sourav Bhowmick,
• Prolay Das and
• Neeladri Das

Beilstein J. Org. Chem. 2014, 10, 1290–1298, doi:10.3762/bjoc.10.130

• (Figure 1). However, both the linear as well as the OC form of the plasmid were observed following incubation with the TPAs 5 and 6 and TPTs 7 and 8. Comparison between the TPAs and TPTs indicates that the former have slightly higher nuclease activity. Complexes with triphenylphosphine as ligands have

4-Hydroxy-6-alkyl-2-pyrones as nucleophilic coupling partners in Mitsunobu reactions and oxa-Michael additions

• Michael J. Burns,
• Thomas O. Ronson,
• Richard J. K. Taylor and
• Ian J. S. Fairlamb

Beilstein J. Org. Chem. 2014, 10, 1159–1165, doi:10.3762/bjoc.10.116

• propiolate esters. Both procedures are mild, tolerate a wide range of functionality, and afford good to excellent yields of products in the majority of cases. Results and Discussion Mitsunobu reactions Using the standard conditions of stirring diisopropyl azodicarboxylate (DIAD) and triphenylphosphine in

• find use in the synthesis of natural products and other bioactive compounds. Experimental General procedure 1: Mitsunobu reaction with 4-hydroxy-2-pyrones: To a stirred solution of the pyrone (1 equiv), triphenylphosphine (1.5 equiv) and alcohol (1.5 equiv), in dichloromethane (4 mL mmol−1) under

Preparation of phosphines through C–P bond formation

• Iris Wauters,
• Wouter Debrouwer and
• Christian V. Stevens

Beilstein J. Org. Chem. 2014, 10, 1064–1096, doi:10.3762/bjoc.10.106

• NiBr2 a mixture of triphenylphosphine 105b and tetraphenylphosphonium bromide salt 114 was obtained (Scheme 32). The first conversion of an aryltriflate to an arylphosphine using diphenylphosphine was reported by Cai et al. (Scheme 33) [208][209]. The method was developed for the synthesis of chiral (R

Regioselective S_N2' Mitsunobu reaction of Morita–Baylis–Hillman alcohols: A facile and stereoselective synthesis of α-alkylidene-β-hydrazino acid derivatives

• Silong Xu,
• Jian Shang,
• Junjie Zhang and
• Yuhai Tang

Beilstein J. Org. Chem. 2014, 10, 990–995, doi:10.3762/bjoc.10.98

• triphenylphosphine is developed, which provides an easy access to α-alkylidene-β-hydrazino acid derivatives in high yields and good stereoselectivity. This reaction represents the first direct transformation of MBH alcohols into hydrazines. Keywords: azodicarboxylate; hydrazine; Mitsunobu reaction; Morita–Baylis

• (2b) and triphenylphosphine under very mild conditions (Scheme 2). To our delight, the reaction was completed in 30 minutes providing the anticipated trisubstituted hydrazine 3b in 90% isolated yield with excellent E-selectivity (E/Z > 20:1). To the best of our knowledge, this reaction represents the

• SN2' Mitsunobu reaction between Morita–Baylis–Hillman (MBH) alcohols, azodicarboxylates, and triphenylphosphine as an efficient synthetic method for α-alkylidene-β-hydrazino acid derivatives in high yields and good stereoselectivity. This reaction features additional advantages as mild conditions

Dimerisation, rhodium complex formation and rearrangements of N-heterocyclic carbenes of indazoles

• Zong Guan,
• Jan C. Namyslo,
• Martin H. H. Drafz,
• Martin Nieger and
• Andreas Schmidt

Beilstein J. Org. Chem. 2014, 10, 832–840, doi:10.3762/bjoc.10.79

• betaines by inter- or intramolecular cycloadditions are typical reactions [18][19]. To prove the initial formation of an N-heterocyclic carbene in this reaction we tried trapping reactions starting from 12a and 12e with carbonylbis(triphenylphosphine)rhodium(I) chloride under otherwise unchanged reaction

• ; ESIMS: m/z (%) = 417 [M + H+]; HRESIMS: C28H25N4 calcd for 417.2079; found: 417.2075. General procedure for the preparation of the rhodium complexes 15 A solution of 0.2 mmol of the indazolium salts 12a and 12e, respectively, and 0.2 mmol of carbonylbis(triphenylphosphine)rhodium(I) chloride in 20 mL of

• (triphenylphosphine)(2-methyl-1-phenyl-1H-indazole-3-ylidene)rhodium(I) hexafluorophosphate (15a) Yield: 73 mg (36%) of yellow crystals; dec. 240 °C; 1H NMR (400 MHz, DMSO-d6) δ 7.67 (d, J = 8.3 Hz, 1H), 7.62–7.60 (m, 3H), 7.56–7.39 (m, 31H), 7.04–6.97 (m, 3H), 6.77 (d, J = 8.3 Hz, 1H), 3.23 (s, 3H) ppm; 13C NMR (150

Silver and gold-catalyzed multicomponent reactions

• Giorgio Abbiati and
• Elisabetta Rossi

Beilstein J. Org. Chem. 2014, 10, 481–513, doi:10.3762/bjoc.10.46

Aminofluorination of 2-alkynylanilines: a Au-catalyzed entry to fluorinated indoles

• Antonio Arcadi,
• Emanuela Pietropaolo,
• Antonello Alvino and
• Véronique Michelet

Beilstein J. Org. Chem. 2014, 10, 449–458, doi:10.3762/bjoc.10.42

• [39]. When the same reaction was performed in the presence of [bis(trifluoromethanesulfonyl)imidate](triphenylphosphine)gold(I) catalyst [40] (5 mol %), the formation of the difluorinated 3H-indole 2a was observed although in low overall yield (Table 1, entry 2). No traces of C–C bond formation, a

Practical synthesis of aryl-2-methyl-3-butyn-2-ols from aryl bromides via conventional and decarboxylative copper-free Sonogashira coupling reactions

• Andrea Caporale,
• Stefano Tartaggia,
• Andrea Castellin and
• Ottorino De Lucchi

Beilstein J. Org. Chem. 2014, 10, 384–393, doi:10.3762/bjoc.10.36

• between 3-bromoaniline (1a) and 4 to give 2-methyl-4-(3-aminophenyl)-3-butyn-2-ol (2a) (Table 1), we screened different bases, solvents and ligands in the absence of copper. We firstly examined the coupling reaction using a catalytic system based on palladium acetate and triphenylphosphine in presence of

Concise, stereodivergent and highly stereoselective synthesis of cis- and trans-2-substituted 3-hydroxypiperidines – development of a phosphite-driven cyclodehydration

• Peter H. Huy,
• Julia C. Westphal and
• Ari M. P. Koskinen

Beilstein J. Org. Chem. 2014, 10, 369–383, doi:10.3762/bjoc.10.35

• of the NK-1 inhibitor L-733,060 in 8 steps. Additionally, a cyclodehydration-realizing simple triethylphosphite as a substitute for triphenylphosphine is developed. Here the stoichiometric oxidized P(V)-byproduct (triethylphosphate) is easily removed during the work up through saponification

• overcoming separation difficulties usually associated to triphenylphosphine oxide. Keywords: amino acids; asymmetric synthesis; cyclodehydration; hydroxypiperidines; natural products; one-pot; Introduction 1,2-Amino alcohols of the type A (Figure 1) represent a frequent core motif of many pharmacologically

Deoxygenative gem-difluoroolefination of carbonyl compounds with (chlorodifluoromethyl)trimethylsilane and triphenylphosphine

• Fei Wang,
• Lingchun Li,
• Chuanfa Ni and
• Jinbo Hu

Beilstein J. Org. Chem. 2014, 10, 344–351, doi:10.3762/bjoc.10.32

• )trimethylsilane (TMSCF2Cl) and triphenylphosphine (PPh3) can be used for the synthesis of gem-difluoroolefins from carbonyl compounds. Comparative experiments demonstrate that TMSCF2Cl is superior to (bromodifluoromethyl)trimethylsilane (TMSCF2Br) and (trifluoromethyl)trimethylsilane (TMSCF3) in this reaction

• TMSCF2Cl was used, TMSCl is not reactive enough to trap the betaine 3, thus the oxaphosphetane 5 could be formed to give olefins and triphenylphosphine oxide (Scheme 4). Finally, the olefination of aldehyde 1b with TMSCF3 as the difluoromethylene source was tested. The results showed that no desired

Diversity-oriented synthesis of dihydrobenzoxazepinones by coupling the Ugi multicomponent reaction with a Mitsunobu cyclization

• Lisa Moni,
• Luca Banfi,
• Andrea Basso,
• Alice Brambilla and
• Renata Riva

Beilstein J. Org. Chem. 2014, 10, 209–212, doi:10.3762/bjoc.10.16

• –d were straightforwardly prepared in excellent yields from low cost starting materials 1, 3, 4, and 7, in all cases passing through the benzyl alcohols (Scheme 1). Apart from 2a [11], they are all new compounds. Initially we reduced azide 2a with PPh3 and separated the amine from triphenylphosphine

• triphenylphosphine oxide. We eventually found that the easiest and most efficient protocol involved reduction with Me3P, followed by evaporation of the solvent and by subsequent Ugi reaction on the crude. With Me3P, phosphazene hydrolysis was much faster and the phosphine oxide was much more easily separated by

Synthesis of five- and six-membered cyclic organic peroxides: Key transformations into peroxide ring-retaining products

• Alexander O. Terent'ev,
• Dmitry A. Borisov,
• Vera A. Vil’ and
• Valery M. Dembitsky

Beilstein J. Org. Chem. 2014, 10, 34–114, doi:10.3762/bjoc.10.6

•  50) [93]. It should be emphasized that this method can be applied in spite of the use of triphenylphosphine, which is a strong reducing agent for peroxides. The alkylation of the sodium salt of alcohol 183 with 2-chloropyrimidine in dimethylformamide gave ozonide 189 (Scheme 51). In this reaction

• azobisisobutyronitrile (AIBN) or ditert-butyl peroxalate (DBPO) as radical initiators. The resulting unstable hydroperoxides are reduced with triphenylphosphine to hydroxy derivatives 209 (Scheme 58, Table 15). The oxidation of acetophenones 210 produces bicyclic 1,2-dioxanes 212 (Scheme 59). It is hypothesized that the