Bis(vinylenedithio)tetrathiafulvalene analogues of BEDT-TTF

• Erdal Ertas,
• İlknur Demirtas and
• Turan Ozturk

Beilstein J. Org. Chem. 2015, 11, 403–415, doi:10.3762/bjoc.11.46

• phosphite at 130 °C for 3 h under a nitrogen atmosphere, which gave a mixture of cross coupled 43 and self coupled products 4a and 44. In order to remove the MEM protecting group, 43 was stirred in 20% HCl at room temperature for 2 days, which yielded the ET analogue 45, having two hydroxy groups. In 2000

• % yields. The fully unsaturated tetraphenyl analogue 52 of ET was obtained in 90% yield by a coupling reaction of 51, which was obtained by converting the thione group of 48 to its corresponding oxo form in 85% yield, in hot triethyl phosphite, yielding 52 in 90% yield (Scheme 7). A charge transfer salt 54

• coupling of 28 with 51 smoothly gave the corresponding ET analogue 56, its reaction with 57 did not produce any result (Scheme 9) [57]. This could be due to the reaction of the benzylphenyldithiole moiety with triethyl phosphite. Analogues of ET, having dithiin and thiophene rings along with hydroxy groups

A simple and efficient method for the preparation of 5-hydroxy-3-acyltetramic acids

• Johanna Trenner and
• Evgeny V. Prusov

Beilstein J. Org. Chem. 2015, 11, 323–327, doi:10.3762/bjoc.11.37

• turned to the alternative oxidation of enolates with molecular oxygen in the presence of triethyl phosphite as originally described by Hartwig [12][13][14][15]. Application of these conditions resulted in a clean conversion to the 5-hydroxy-3-acyltetramic acid but again, the isolated yield of the product

Synthesis of dinucleoside acylphosphonites by phosphonodiamidite chemistry and investigation of phosphorus epimerization

• William H. Hersh

Beilstein J. Org. Chem. 2015, 11, 184–191, doi:10.3762/bjoc.11.19

• barrier was found to be high as no epimerization was detected up to 150 °C, and consistent with this, density functional theory calculations give an inversion barrier of over 40 kcal/mol. Keywords: acylphosphine; acyl phosphite; chiral; DFT; NMR; nucleic acids; oligonucleotides; Introduction Antisense

• interference has also been described [24]. We recently reported the synthesis of a number of chiral disulfide sulfurizing reagents [25] and the results of the sulfurization of phosphite triesters in order to look for stereoselectivity [26]. In order to change such a method into a practical synthesis route for

• several groups suggests that the inversion barrier is decreased to below 20 kcal/mol [28][29][30]. In order to extend the comparison from phosphines to phosphites, we recently showed that dinucleoside phosphite triesters, like phosphines, epimerize slowly – in this case at 150 °C with an inversion barrier

Synthesis and biological evaluation of novel N-α-haloacylated homoserine lactones as quorum sensing modulators

• Michail Syrpas,
• Ewout Ruysbergh,
• Christian V. Stevens,
• Norbert De Kimpe and
• Sven Mangelinckx

Beilstein J. Org. Chem. 2014, 10, 2539–2549, doi:10.3762/bjoc.10.265

• group for the enolization of the carbonyl function facilitating α-monochlorination under mild conditions. α-Chlorinated acylphosphonates can be easily cleaved by a nucleophile with the expulsion of phosphite. Therefore, the α-chloro acylphosphonates 10a–f were transformed to the corresponding

Superoxide chemistry revisited: synthesis of tetrachloro-substituted methylenenortricyclenes

• Basavaraj M. Budanur and
• Faiz Ahmed Khan

Beilstein J. Org. Chem. 2014, 10, 2531–2538, doi:10.3762/bjoc.10.264

• have not been studied systematically even though discovered more than half a century ago. Alkylpentachlorocyclopentadienes can be easily prepared from hexachlorocyclopentadiene by treatment with the corresponding phosphite esters by a known protocol [37]. 5-Alkylpentachlorocyclopentadienes were rarely

Solution phase synthesis of short oligoribonucleotides on a precipitative tetrapodal support

• Alejandro Gimenez Molina,
• Amit M. Jabgunde,
• Pasi Virta and
• Harri Lönnberg

Beilstein J. Org. Chem. 2014, 10, 2279–2285, doi:10.3762/bjoc.10.237

• synthetic cycle was composed of three steps, as usual: coupling, oxidation and deprotection. Couplings were carried out in a 1:1 mixture of MeCN and DMF under N2 using 1.5 equiv of the respective phosphoramidite building block per a support-bound 5'-hydroxy group. After coupling, the phosphite triester

Pyrrolidine nucleotide analogs with a tunable conformation

• Lenka Poštová Slavětínská,
• Dominik Rejman and
• Radek Pohl

Beilstein J. Org. Chem. 2014, 10, 1967–1980, doi:10.3762/bjoc.10.205

• derivatives 7–10 were prepared from pyrrolidine azanucleosides 15a–d [5][15] via a Mannich-type reaction with diisopropyl phosphite and aqueous formaldehyde at elevated temperature in good yields (Scheme 1). The obtained diisopropyl esters 17a–d were deprotected by treatment with trimethylsilyl bromide in

Application of cyclic phosphonamide reagents in the total synthesis of natural products and biologically active molecules

• Thilo Focken and
• Stephen Hanessian

Beilstein J. Org. Chem. 2014, 10, 1848–1877, doi:10.3762/bjoc.10.195

• phosphonamides through alkylation of bicyclic phosphite anions [69][70][71]. Thus, condensation of diamine 58 with phosphorus trichloride followed by hydrolysis of the formed 2-chloro-1,3,2-diazaphospholidine with one equivalent of water gave phosphorus acid diamide 68. The latter could be deprotonated with LDA

Structure/affinity studies in the bicyclo-DNA series: Synthesis and properties of oligonucleotides containing bc^en-T and iso-tricyclo-T nucleosides

• Branislav Dugovic,
• Michael Wagner and
• Christian J. Leumann

Beilstein J. Org. Chem. 2014, 10, 1840–1847, doi:10.3762/bjoc.10.194

• the modified residues, most likely on the level of the iodinated phosphite intermediate [35], leading to the formation of an allylic carbocation in the bcen-T unit and 5’-phosphorylated DNA fragment (Scheme 3). The synthesis of oligonucleotides using building block 10 proved to be even more difficult

Multicomponent reactions in nucleoside chemistry

• Mariola Koszytkowska-Stawińska and
• Włodzimierz Buchowicz

Beilstein J. Org. Chem. 2014, 10, 1706–1732, doi:10.3762/bjoc.10.179

• reaction (Scheme 11) proceeds in a three-component system involving a carbonyl compound (aldehyde or ketone), amine, and a hydrophosphoryl compound (mainly alkyl/aryl phosphite) [74][75]. The reaction products, commonly termed as α-aminophoshonates, display properties of industrial and/or medical interest

• phosphite were carried out under solvent-free conditions at 60 °C (for 14) or at 80 °C (for 27). Products 28 and 29 were obtained in good to excellent yields as 1:1 diastereoisomeric mixtures arising from the generation of a stereogenic center at the aminophosphonate chain. The mixtures were not separated

Rational design of cyclopropane-based chiral PHOX ligands for intermolecular asymmetric Heck reaction

• Marina Rubina,
• William M. Sherrill,
• Alexey Yu. Barkov and
• Michael Rubin

Beilstein J. Org. Chem. 2014, 10, 1536–1548, doi:10.3762/bjoc.10.158

• substrates [59]. A highly efficient asymmetric arylation in the presence of sugar-derived phosphite-oxazoline ligands was reported by Diéguez and Pàmies [47][48]. PHOX ligands are very appealing due to their high catalytic potential and modular design, which permits easy preparation of a series of analogues

Synthesis of 1-[bis(trifluoromethyl)phosphine]-1’-oxazolinylferrocene ligands and their application in regio- and enantioselective Pd-catalyzed allylic alkylation of monosubstituted allyl substrates

• Zeng-Wei Lai,
• Rong-Fei Yang,
• Ke-Yin Ye,
• Hongbin Sun and
• Shu-Li You

Beilstein J. Org. Chem. 2014, 10, 1261–1266, doi:10.3762/bjoc.10.126

• branched monosubstituted allyl acetate favoring the branched products. However, linear products were favored when the linear allyl substrates were employed [23][24]. The chiral oxazoline–phosphite ligands introduced by Pfaltz and coworkers proved to be highly efficient for regio- and enantiocontrol in the

Atherton–Todd reaction: mechanism, scope and applications

• Stéphanie S. Le Corre,
• Mathieu Berchel,
• Hélène Couthon-Gourvès,
• Jean-Pierre Haelters and
• Paul-Alain Jaffrès

Beilstein J. Org. Chem. 2014, 10, 1166–1196, doi:10.3762/bjoc.10.117

• Atherton–Todd (AT) reaction was applied for the synthesis of phosphoramidates by reacting dialkyl phosphite with a primary amine in the presence of carbon tetrachloride. These reaction conditions were subsequently modified with the aim to optimize them and the reaction was extended to different

• by chance. Indeed, these authors attempted to purify a solution of dibenzyl phosphite in carbon tetrachloride by its treatment with an aqueous ammonia solution. They observed the formation of a precipitate that was identified as O,O-dibenzyl phosphoramidate. However, no reaction occurred when

• dibenzyl phosphite was mixed alone with carbon tetrachloride, whereas an exothermal reaction occurred if gaseous ammonia was passed through this solution or if this solution was shaken with an aqueous ammonia solution, with chloroform and ammonium chloride as byproducts. The replacement of ammonia with

Addition of H-phosphonates to quinine-derived carbonyl compounds. An unexpected C9 phosphonate–phosphate rearrangement and tandem intramolecular piperidine elimination

• Łukasz Górecki,
• Artur Mucha and
• Paweł Kafarski

Beilstein J. Org. Chem. 2014, 10, 883–889, doi:10.3762/bjoc.10.85

• skeleton and a phosphorus atom. For the C9 ketones a phosphonate–phosphate rearrangement, associated with a tandem elimination of the piperidine fragment, was evidenced. Keywords: carbonyl derivatives; dialkyl phosphite addition; organophosporus; phosphonate–phosphate rearrangement; quinine oxidation

• % yield. The obtained aldehydes 4, 6, and 8 were reacted with 1.1 equiv of diethyl phosphite. The presence of the tertiary amino group of quinuclidine was expected to be a sufficient catalytic base for the addition reaction, and furthermore to induce a diastereoselectivity. However, the expected

• was treated with diethyl phosphite and heated in toluene at 50 °C for a week with addition of a catalytic amount of triethylamine (Scheme 4). The reaction mixture was purified by column chromatography. Formation of four diastereomeric compounds, derivatives of epiquinidine (8R,9R), quinidine (8R,9S

Synthesis of fluorescent (benzyloxycarbonylamino)(aryl)methylphosphonates

• Michał Górny vel Górniak,
• Anna Czernicka,
• Piotr Młynarz,
• Waldemar Balcerzak and
• Paweł Kafarski

Beilstein J. Org. Chem. 2014, 10, 741–745, doi:10.3762/bjoc.10.68

• (Scheme 1) with good yields (59–86%). Unfortunately, the reaction of phosphite obtained from 7-hydroxycoumarine failed, since it appeared to be unstable upon harsh reaction conditions and underwent decomposition as seen by 31P NMR. Therefore, we have decided to apply a more delicate procedure described

• recently by Goldeman and Soroka [21]. According to this procedure the reaction was carried out in dry chloroform in the presence of catalytic amounts of tetrafluoroboric acid. Unfortunately, tri(7-hydroxycoumaric) phosphite also underwent decomposition under these conditions. The diaryl esters 2 exhibit

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

• Scheme 21). This can be a simple nucleophile (indole 30, imidazole 31, diethyl phosphite (32), Scheme 20) [53][54][55] or can be generated in situ (enolate 33, enamine 34, Scheme 21) [56][57] from a suitable precursor and a second catalyst (dual activation strategy) affording 1,3-disubstituted-1,2

• electron-rich and electron-poor anilines are suitable partners for these reactions, whereas alkylamines and benzylamine gave worse results. Moreover, the third partner (Nu in Scheme 19) is limited to one substrate as in the reaction employing diethyl phosphite (32). Indoles 30 and imidazoles 31 can bear

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

• the step-economic and stereodivergent synthesis of trans- and cis-2-substituted 3-piperidinols B, we want to report the development of this sequence in more detail with a focus on the phosphite-mediated cyclodehydration. Additionally, the synthesis of a side chain functionalized piperidinol derived

• hours of reflux, see Table 2, entry 3). Chromatographic purification of the crude piperidinols 11a–d, which were already isolated in 85–90% purity (from the phosphite cyclodehydration), was best achieved with halogen free iPrOH/Et3N/hexane eluent mixtures (ratio 0.8–3:2–4:100 depending on the polarity

• effect we chose a ratio of Et3N/CH2Cl2 1:2 as standard conditions for the phosphite mediated cyclodehydration. Typically, 5 to 6 equivalents of Et3N resulting in a reasonable concentration of the substrates 11 and 12 (see Table 3) of 0.4–0.5 mol/L (in Et3N/CH2Cl2) were sufficient enough to guarantee

New developments in gold-catalyzed manipulation of inactivated alkenes

• Michel Chiarucci and
• Marco Bandini

Beilstein J. Org. Chem. 2013, 9, 2586–2614, doi:10.3762/bjoc.9.294

• were accessed by intramolecular addition in excellent yields (Scheme 8b). The combined use of more electrophilic phosphite-gold complexes [41][42] and enabling techniques such as microwave irradiation [43] led to consistent improvement in efficiency of the catalytic system. In particular when (Ph3O

Gold(I)-catalyzed enantioselective cycloaddition reactions

• Fernando López and
• José L. Mascareñas

Beilstein J. Org. Chem. 2013, 9, 2250–2264, doi:10.3762/bjoc.9.264

• allyl cation to the diene. Curiously, by using a gold(I) catalyst bearing a π-acceptor phosphite ligand, such as Au10/AgSbF6, allenedienes disubstituted at the distal position of the allene lead to products formally arising from a [4 + 2] cycloaddition process (Scheme 8, b) [59][60]. Several

• substituents at the Binol ortho-positions (Au11, Scheme 9) [60]. Independently, Toste and co-workers reported that the related phosphoramidite–gold complex Au12, and the chiral gold catalyst Au13, derived from a C3-symmetric phosphite [66], were also able to induce excellent enantioselectivities in these [4

• include a phosphite–gold complex Au10 and a biaryldi-tert-butylphosphine–gold complex (Au3) [74][75][76]. More recently, González and co-workers accomplished the enantioselective version of these annulations between sulfonyl allenamides and vinylarenes, providing a straightforward entry into optically

Gold(I)-catalyzed hydroarylation reaction of aryl (3-iodoprop-2-yn-1-yl) ethers: synthesis of 3-iodo-2H-chromene derivatives

• Pablo Morán-Poladura,
• Eduardo Rubio and
• José M. González

Beilstein J. Org. Chem. 2013, 9, 2120–2128, doi:10.3762/bjoc.9.249

• competition with a direct Friedel–Crafts-type cyclization reaction yielding 3. In previous work dealing with the cyclization of N-(3-iodoprop-2-ynyl)-N-tosylanilines to give related 1,2-dihydroquinolines (Scheme 4A, X = NTs) [43], we documented for a phosphite-based gold-catalyst, which render a more

Stability of SG1 nitroxide towards unprotected sugar and lithium salts: a preamble to cellulose modification by nitroxide-mediated graft polymerization

• Guillaume Moreira,
• Laurence Charles,
• Mohamed Major,
• Florence Vacandio,
• Yohann Guillaneuf,
• Catherine Lefay and
• Didier Gigmes

Beilstein J. Org. Chem. 2013, 9, 1589–1600, doi:10.3762/bjoc.9.181

• Erba), ethyl acetate (EtOAc, Carlo Erba), triethyl phosphite (P(O)(OEt)3, Aldrich, 99+% ), and tert-butylbenzene (t-BuPh, Aldrich, 99%) were used as received. The 2-methyl-2-(N-tert-butyl-N-(1-diethoxyphosphoryl-2,2-dimethylpropyl)aminoxy)-propionic acid alkoxyamine (BlocBuilder MA, BB) was kindly

Methylidynetrisphosphonates: Promising C₁ building block for the design of phosphate mimetics

• Vadim D. Romanenko and
• Valery P. Kukhar

Beilstein J. Org. Chem. 2013, 9, 991–1001, doi:10.3762/bjoc.9.114

• ]. Review Preparation of methylidynetrisphosphonates Synthesis via a Michaelis–Arbuzov reaction Phosphonate esters are often prepared through Michaelis–Arbuzov reaction of a trialkyl phosphite with an alkyl halide [9]. However, contrary to the early patent claims, trisphosphonate esters cannot be derived

• from simple trihalomethyl derivatives [10][11][12]. Indeed, chloroform and bromoform do not react with triethyl phosphite even under harsh conditions [11]. In addition, no reaction occurred between benzotrichloride (PhCCl3) and triethyl phosphite at a temperature below 150 °C. The CuCl-catalyzed

• reaction of PhCCl3 and (EtO)3P at 120–140 °C produced 1,2-diphenyl-1,1,2,2-tetrachloroethane [13]. The early work reported that the trisphosphonate PhC(PO3Et2)3 was formed from triethyl phosphite and dibenzoyl peroxide when reagents were boiled under reflux in chloroform, but proof of the trisphosphonate

An improved synthesis of a fluorophosphonate–polyethylene glycol–biotin probe and its use against competitive substrates

• Hao Xu,
• Hairat Sabit,
• Gordon L. Amidon and
• H. D. Hollis Showalter

Beilstein J. Org. Chem. 2013, 9, 89–96, doi:10.3762/bjoc.9.12

• combined 90% yield. The phosphonate moiety was installed under standard Arbuzov conditions by heating 4b under reflux in neat triethyl phosphite for 1 h to provide novel intermediate 5 in 92% yield following purification by column chromatography. Clean removal of the benzyl protecting group under standard

• -phenyl-2,5,8,11-tetraoxatridecan-13-yl)phosphonate (5): Iodobenzyl polyether 4b (17.44 g, 44.23 mmol) and triethyl phosphite (32 mL, 183.9 mmol) were mixed in an oven-dried round-bottom flask and heated under reflux for 1 h. Excess triethyl phosphite was removed under vacuum and the reaction mixture was

Automated synthesis of sialylated oligosaccharides

• Davide Esposito,
• Mattan Hurevich,
• Bastien Castagner,
• Cheng-Chung Wang and
• Peter H. Seeberger

Beilstein J. Org. Chem. 2012, 8, 1601–1609, doi:10.3762/bjoc.8.183

• and 3). The glycosylation of galactal 2 with phosphite 1, which we described in the supporting information of [5], was further optimized. In particular, elevating the reaction temperature proved beneficial and disaccharide 9 was isolated in higher overall yield, albeit with a slight decrease in

Synthesis of fluoranthenes by hydroarylation of alkynes catalyzed by gold(I) or gallium trichloride

• Sergio Pascual,
• Christophe Bour,
• Paula de Mendoza and
• Antonio M. Echavarren

Beilstein J. Org. Chem. 2011, 7, 1520–1525, doi:10.3762/bjoc.7.178

• demonstrated to be amongst the best catalysts in many gold(I)-catalyzed cyclizations [6][58]. No reaction was observed with complex 5 after heating for 5 min at 70 °C in CH2Cl2 under microwave irradiation (Table 1, entry 1), whereas the more electrophilic 6, bearing a less donating phosphite ligand, led almost

• -tetrahydrofluoranthene, and 8a, the crude mixtures were treated with excess DDQ in toluene under reflux to provide pure 8a. No reaction or decomposition was observed when the reaction was carried out with gold(I) complex 5 (Table 2, entries 1 and 2). In contrast, the more electrophilic gold(I) complex 6 with phosphite

• Highly electrophilic gold(I) catalyst 6 with a bulky phosphite ligand competes with GaCl3 as the catalyst of choice for the hydroarylation of alkynes. The synthetic potential of this catalyst is illustrated by the synthesis of functionalized triarylated decacyclenes in which three C–C bonds are formed