Regioselective ester cleavage during the preparation of bisphosphonate methacrylate monomers

• Kamel Chougrani,
• Gilles Niel,
• Bernard Boutevin and
• Ghislain David

Beilstein J. Org. Chem. 2011, 7, 364–368, doi:10.3762/bjoc.7.46

• –5c started from 6-aminohexanoic acid (11) and 11-aminoundecanoic acid (12), respectively. The three component coupling of 11, respectively 12, with paraformaldehyde and dimethyl phosphite furnished bisphosphonates 13 and 14 in excellent yields. These latter compounds were then reduced

Palladium-catalyzed formation of oxazolidinones from biscarbamates: a mechanistic study

• Benan Kilbas and
• Metin Balci

Beilstein J. Org. Chem. 2011, 7, 246–253, doi:10.3762/bjoc.7.33

• of the palladium catalyst in THF, prepared from tris(dibenzylideneacetone)dipalladium chloroform complex and triisopropyl phosphite. The resulting oxazolidinone 9 was purified by chromatography on a silica gel column to give a crystalline product in 58% yield. The structure and configuration of 9 was

• -3,3a,5a,6,6a,6b-hexahydro-2H-cyclopropa[3,4]benzo[1,2-d][1,3]oxazole-6-carboxylate (9): Tris(dibenzylideneacetone)dipalladium chloroform complex (0.2 g, 193.6 mmol) was dissolved in freshly distilled THF (20 mL) under a nitrogen atmosphere. Triisopropyl phosphite (1.6 mL) in THF (5 mL) was then added

Approaches towards the synthesis of 5-aminopyrazoles

• Ranjana Aggarwal,
• Vinod Kumar,
• Rajiv Kumar and
• Shiv P. Singh

Beilstein J. Org. Chem. 2011, 7, 179–197, doi:10.3762/bjoc.7.25

•  21) [61][62]. An interesting synthesis of 5(3)-aminopyrazoles 81 and 82 [63] has been developed using thioacetals 79 and 80 of malononitrile, which are conveniently obtained by the reaction of aniline and diethyl phosphite with bis(methylthio)methylenemalononitrile 74d, respectively. Reaction with

Redox-active tetrathiafulvalene and dithiolene compounds derived from allylic 1,4-diol rearrangement products of disubstituted 1,3-dithiole derivatives

• Filipe Vilela,
• Peter J. Skabara,
• Christopher R. Mason,
• Thomas D. J. Westgate,
• Asun Luquin,
• Simon J. Coles and
• Michael B. Hursthouse

Beilstein J. Org. Chem. 2010, 6, 1002–1014, doi:10.3762/bjoc.6.113

• to extensive investigations of the chemistry of 1,3-dithiole-2-thione (1, Figure 1) [1][2], since this heterocycle and its derivatives are frequently used as convenient precursors to TTF compounds through phosphite-mediated coupling [3]. Our efforts to prepare triaryl derivatives of compound 1 led to

• derivatives have been reported [19], treatment of 22 with triethyl phosphite did not give the desired self-coupled TTF compound 23. The X-ray structure of 22 is shown in Figure 3. The molecule possesses an inversion centre located at the C(22)–C(22’) bond. A close intramolecular contact is observed between S

• processability for the annelated products [23][24][25]. The thione group in 3 has the potential for several synthetically useful manipulations (Scheme 6). Compound 3 was shown to be a synthetically versatile compound. Refluxing of 3 in triethyl phosphite followed by purification by filtration through silica gel

Aromatic and heterocyclic perfluoroalkyl sulfides. Methods of preparation

• Vladimir N. Boiko

Beilstein J. Org. Chem. 2010, 6, 880–921, doi:10.3762/bjoc.6.88

• presumably as the result of photo-substitution of chlorine in 4-trifluoromethylsulfanylchorobenzene by an SRN1 mechanism. HMPA suppressed this side-reaction (similar to iodobenzene with potassium diethyl phosphite [180]) and promoted trifluoromethylation (Table 6). The reaction solvent is important and the

Unexpected degradation of the bisphosphonate P-C-P bridge under mild conditions

• Petri A. Turhanen and
• Jouko J. Vepsäläinen

Beilstein J. Org. Chem. 2008, 4, No. 7, doi:10.1186/1860-5397-4-7

• reaction conditions in two of the prepared etidronate derivatives. Earlier, Szymczak et. al. [24] have described the formation of H-phosphonate (also known as phosphite) and phosphate components from a phosphonate-phosphate compound (same kind of structure as 8 in Scheme 1) either in CH3CN/Et3N/H2O (v/v

• ) or phosphate buffer, pH 7.4 at 37 °C. Szajnman et. al. [25] has reported loss of two molecules of phosphite in tetraethyl oxirane-2,2-diylbis(phosphonate); however the kind of degradation which we will discuss in this paper has not been previously reported. Results and Discussion As mentioned in the

• introduction, the P-C-P bridge of BPs has been reported to be relatively stable against chemical hydrolysis, however here we report the unexpectedly easy degradation of two etidronate derivatives into acetate and phosphite moieties. In our ongoing study to prepare novel biodegradable BP derivatives, a new

Analogues of amphibian alkaloids: total synthesis of (5R,8S,8aS)-(−)-8-methyl- 5-pentyloctahydroindolizine (8-epi-indolizidine 209B) and [(1S,4R,9aS)-(−)-4-pentyloctahydro- 2H-quinolizin- 1-yl]methanol

• Joseph P. Michael,
• Claudia Accone,
• Charles B. de Koning and
• Christiaan W. van der Westhuyzen

Beilstein J. Org. Chem. 2008, 4, No. 5, doi:10.1186/1860-5397-4-5

• was then effected by first treating the thiolactam with ethyl bromoacetate, after which reaction of the resulting S-alkylated intermediate with triethyl phosphite and triethylamine in acetonitrile gave the vinylogous urethane (+)-28 in 75% yield. At this stage, however, our fears of the discrepant

Part 1. Reduction of S-alkyl- thionocarbonates and related compounds in the presence of trialkylboranes/air

• Jean Boivin and
• Van Tai Nguyen

Beilstein J. Org. Chem. 2007, 3, No. 45, doi:10.1186/1860-5397-3-45

• dithiocarbonates and we therefore proposed diethyl phosphite/DLP and H3PO2/Et3N/AIBN as attractive reagents for this purpose that circumvent these impediments.[11] The core of the results reported in this paper and the following parts,[12][13] has been presented as communications at the Xth Symposium of the

Pd-catalysed [3 + 3] annelations in the stereoselective synthesis of indolizidines

• Olivier Y. Provoost,
• Andrew J. Hazelwood and
• Joseph P. A. Harrity

Beilstein J. Org. Chem. 2007, 3, No. 8, doi:10.1186/1860-5397-3-8

• generation of the intermediate TMM-reagent [12]. However, the ability of phosphite to carry out the reduction of Pd(II) to Pd(0) suggested to us that the annelation should proceed equally well in the absence of n-BuLi [13]. In an effort to clarify this issue we carried out a study of the [3 + 3] reaction in

A superior P-H phosphonite: Asymmetric allylic substitutions with fenchol- based palladium catalysts

• Bernd Goldfuss,
• Thomas Löschmann,
• Tina Kop-Weiershausen,
• Jörg Neudörfl and
• Frank Rominger

Beilstein J. Org. Chem. 2006, 2, No. 7, doi:10.1186/1860-5397-2-7

• , reflecting the effect of steric demanding and electron donating pyridine groups on enantioselectivity. The surprisingly stable halogen phosphites BIFOP-Cl and BIFOP-Br yield even higher enantioselectivities (39% and 37% ee) than the corresponding phosphite BIFOP-OPh or the phosphoramidite BIFOP-NEt2 (10% and

Synthesis of phosphorothioates using thiophosphate salts

• Babak Kaboudin and
• Fatemeh Farjadian

Beilstein J. Org. Chem. 2006, 2, No. 4, doi:10.1186/1860-5397-2-4

• benzoyl chloride (a hard electrophile), gave the O-acylation product. A simple, efficient, and general method has been developed for the synthesis of phosphorothioates through a one-pot reaction of alkyl halides with the mixture of diethyl phosphite in the presence of triethylamine/sulfur/and acidic

• the utility of surface-mediated reactions for the synthesis of organophosphorus compounds, [37][38][39][40][41][42][43][44][45][46][47][48] we report a new method for the preparation of phosphorothioates by reaction of diethyl phosphite with alkyl halides in the presence of a mixture of ammonium

• them, depending on conditions, and mixtures are often obtained in the reaction with electrophilic centers (Scheme 2). [50] We have found that the reaction of diethyl phosphite with alkyl halides in the presence of a mixture of ammonium acetate/sulfur/alumina under solvent-free conditions using

New modification of the Perkow reaction: halocarboxylate anions as leaving groups in 3-acyloxyquinoline- 2,4(1H,3H)-dione compounds

• Oldřich Paleta,
• Karel Pomeisl,
• Stanislav Kafka,
• Antonín Klásek and
• Vladislav Kubelka

Beilstein J. Org. Chem. 2005, 1, No. 17, doi:10.1186/1860-5397-1-17

• 72 Zlín, Czech Republic Zentiva, U Kabelovny 130, 10237 Prague 10, Czech Republic 10.1186/1860-5397-1-17 Abstract Substituted 3-(fluoroacyloxy)quinoline-2,4(1H,3H)-diones including 3-(fluoroiodoacetoxy) derivatives react with triethyl phosphite to afford either the product of the Perkow reaction or

• reaction of halocompounds, the observed leaving groups were the halogen anions. However, in the reaction of pentaacetylated D-fructose with trimethyl phosphite the acetyloxy anion as the leaving group was also observed. [10] This rather unusual transformation may be attributed to the structural nature of

• the sugar skeleton and its multiple acetoxy groups. In this communication we would like to report on the ability of halocarboxylate anions to act as leaving groups in the reactions of 3-(haloacyloxy)-quinoline-2,4(1H,3H)-diones with triethyl phosphite to afford 8 and 9, the products of the Perkow

An exceptional P-H phosphonite: Biphenyl- 2,2'-bisfenchylchlorophosphite and derived ligands (BIFOPs) in enantioselective copper- catalyzed 1,4-additions

• T. Kop-Weiershausen,
• J. Lex,
• J.-M. Neudörfl and
• B. Goldfuss

Beilstein J. Org. Chem. 2005, 1, No. 6, doi:10.1186/1860-5397-1-6

• as well as hydridic and organometallic nucleophiles. Chloride substitution in BIFOP-Cl proceeds only under drastic conditions. New enantiopure, sterically demanding phosphorus ligands such as a phosphoramidite, a phosphite and a P-H phosphonite (BIFOP-H) are hereby accessible. In enantioselective Cu

• -catalyzed 1,4-additions of ZnEt2 to 2-cyclohexen-1-one, this P-H phosphonite (yielding 65% ee) exceeds even the corresponding phosphite and phosphoramidite. Keywords: phosphorus ligands; chirality; biaryls; asymmetric conjugate additions; phosphoramidites; phosphites; phosphonites; X-ray analyses

• and LiNEt2. While no hydrolysis of 1 is observed at ambient temperature, only reflux and basic conditions (KOH) yield complete hydrolysis of 1 to BIFOP(O)-H, 8 (98%, Table 1, entry 14, Figure 5). [79][80] The phosphite BIFOP-OPh, 6 (40%, Figure 6) and the phosphoramidite BIFOP-NEt2, 7 (47%, Figure 7

Mixtures of monodentate P-ligands as a means to control the diastereoselectivity in Rh-catalyzed hydrogenation of chiral alkenes

• Manfred T. Reetz and
• Hongchao Guo

Beilstein J. Org. Chem. 2005, 1, No. 3, doi:10.1186/1860-5397-1-3

• a diastereoselectivity of only 5:1 (entry 17). Another noteworthy catalyst system is composed of the bulky phosphite P22. This ligand alone delivers a moderate diasteroselectivity of 4:1 (entry 20), whereas various hetero-combinations based on P22 and other P-ligands induce markedly enhanced