bluuebunny/crossref_metadata_2025 huggingface dataset:
Fine‐needle aspiration of an unusual case of poorly differentiated insular carcinoma of the thyroid
Authors: Gong Yun , Krishnamurthy Savitri
Published: January 2005

Poorly differentiated insular carcinoma of the thyroid is a rare thyroid malignancy that is intermediary in biological behavior between well‐differentiated and undifferentiated thyroid carcinoma. We used fine‐needle aspiration (FNA) to diagnose a poorly differentiated insular carcinoma with unusual cytological features in a 53‐yr‐old woman with a history of goiter and hypothyroidism, who presented with a massively enlarged thyroid gland and a large liver metastasis. The hypercellular aspirates were comprised predominantly of individually dispersed tumor cells. The tumor cells were small, monotonous, round to oval, and often plasmacytoid with eccentric hyperchromatic nuclei and occasional binucleation; finely granular, ill‐defined cytoplasm; and smooth nuclear contours, with hyperchromasia, and small to inconspicuous nucleoli. There were no identifiable microfollicles, necrosis, and mitotic figures. The differential diagnosis included poorly differentiated insular carcinoma, medullary carcinoma of the thyroid, and low‐grade lymphoma. Immunocytochemical staining for thyroglobulin, calcitonin, and CD45 yielded negative findings. The insular pattern and scattered microfollicles were appreciated only focally in the specimen from the total thyroidectomy, which also showed other histological patterns including solid, trabecular, and papillary forms. In addition to small, uniform cells, Hürthloid, columnar, and clear cells were focally noted. Thyroglobulin immunoreactivity was recognized only in areas with well‐formed follicles. In view of the aggressive nature of insular carcinoma, preoperative recognition is important in planning appropriate therapy. Familiarity with the cytomorphological features, a high index of suspicion, and consideration of appropriate differential diagnoses can greatly aid in reaching a definitive preoperative diagnosis. The limitations of FNA in the sampling of a large tumor with heterogeneous patterns should be kept in mind when interpreting the cytomorphological and immunocytochemical results. Diagn. Cytopathol. 2005;32:103–107. © 2005 Wiley‐Liss, Inc.
Atypical papillary proliferation in gynecologic patients: A study of 32 pelvic washes
Authors: Ventura Karyna C. , Yang Grace C.H. , Levine Pascale Hummel
Published: January 2005

Papillary clusters in gynecologic pelvic washes frequently cause diagnostic challenges because they can be associated with borderline or malignant ovarian tumors, as well as benign pelvic diseases. The objective of our study was to review all pelvic washes with atypical papillary proliferation (APP) and investigate whether cytomorphology and/or immunohistochemistry on cell block could determine their origin. Thirty‐two pelvic washes from 31 patients containing APP were reviewed and correlated with their corresponding gynecologic or pelvic disease. Previously obtained cell blocks with immunohistochemical (IHC) stains were reviewed also. Nine of 32 washes (28%) were overcalled as malignant and were from patients with 5 borderline serous ovarian tumors (BSTO), 1 ovarian follicular cyst, 1 serous cystadenofibroma, and 1 endometrial carcinoma with ovarian seromucinous cystadenoma. BSTO and endometriosis were the most common sources of APP. Cell blocks could not discriminate further the etiology of APP. Immunohistochemistry was performed rarely and not fully contributory. Caution in interpreting papillary groups and cytohistological correlation is recommended to prevent a high false positive rate. Diagn. Cytopathol. 2005;32:76–81. © 2005 Wiley‐Liss, Inc.
Azaferrocenophanes with Azobenzene‐Containing Ligands − Protonation and Electrochemical Oxidation of the Molecule Influences the Absorption Spectra and cis−trans Isomerization of the Azobenzene Group
Authors: Sakano Tatsuaki , Horie Masaki , Osakada Kohtaro , Nakao Hidenobu
Published: January 2005

N‐{4‐(Phenylazo)phenyl}aminophenyl‐2‐aza‐[3]‐ferrocenophane (4) and N‐{3‐(phenylazo)phenyl}aminophenyl‐2‐aza‐[3]‐ferrocenophane (5) have been prepared by C−N bond‐forming reactions catalyzed by Ru and Pd complexes. The absorption peaks due to the π−π* transition of the trans‐azobenzene group of 4 and 5 appear at 442 and 426 nm, respectively, in toluene. Photoirradiation of solutions of 4 and 5 at 420 nm causes partial isomerization of the trans‐azobenzene group to cis‐azobenzene and reaches a photostationary state. The compounds at the photostationary state undergo thermal isomerization of the cis‐azobenzene group to the trans isomer. The isomerization after one‐electron oxidation of the compounds takes place more rapidly than that without electrochemical oxidation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)
Effects of preconditioning on the accuracy and efficiency of incompressible flows
Authors: Patel S. , Drikakis D.
Published: January 2005

An investigation of some form of preconditioning approach for the incompressible Navier–Stokes equations is presented. We have implemented preconditioning in conjunction with a high‐resolution (characteristics‐based) scheme for the advective terms, a non‐linear multigrid algorithm and an explicit fourth‐order, total variation diminishing (TVD) Runge–Kutta scheme. Computations have been carried out for flows through suddenly‐expanded and expanded–contracted geometries, for a broad range of Reynolds numbers, featuring flow separation as well as instabilities. We present comparisons of the preconditioned and non‐preconditioned solutions against experimental and previous computational results and show that for the cases exhibiting instabilities, preconditioning has a positive effect on the convergence, but the accuracy is adversely affected. Further investigations of other forms of preconditioning need to be performed in order to shed light on the above issues. Copyright © 2005 John Wiley & Sons, Ltd.
Contrasting chemical and physical properties of [o‐ and [p‐(N,N‐dimethylamino) phenyl]phosphines and phosphonium salts
Authors: Cairns S. Matthew , McEwen William E.
Published: January 2005

The rate of alkylation of (2‐N,N‐dimethylaminophenyl)diphenylphosphine with benzyl bromide in chloroform is faster than that of the corresponding reaction of (4‐N,N‐dimethylaminophenyl)diphenylphosphine. This result is discussed in terms of a through‐space N2p–P(IV) interaction for the former.

The rate of alkaline cleavage of benzyl(4‐N,N‐dimethylaminophenyl)diphenylphosphonium bromide, which gives toluene, is slower than the rate of alkaline cleavage of benzyl(2‐N,N‐dimethylaminophenyl)diphenylphosphonium bromide, which gives dimethylaniline. This result is also discussed in terms of the through‐space N2p–P(IV) interaction.

The 31P NMR spectra of a series of ortho‐dimethylamino‐substituted triarylphosphines and benzyltriarylphosphonium halides show that the phosphorus atom is more shielded than in the corresponding para‐dimethylamino compounds, as anticipated on the basis of an N2p–P(IV) interaction for the former.
The Chemistry of N‐substituted benzotriazoles. Part 22 [1]: Transformations of 1‐(trimethylsilylmethyl)benzotriazole
Authors: Katritzky Alan R. , Lam Jamshed N.
Published: January 2005

1‐(Trimethylsilylmethyl)benzotriazole is readily prepared from benzotriazole and chloromethyltrimethylsilane. It undergoes fluoride‐catalyzed desilylation with carbonyl compounds and forms an anion that can be alkylated and acylated readily and undergoes Peterson olefination. 1‐(Cyclohexylidenemethyl)benzotriazole is lithiated exclusively at the α carbon atom, and the anion can be cleanly alkylated.

1‐(α‐Acylalkyl)benzotriazoles are reduced to ketones with zinc and acid. The stability of 1‐alkenylbenzotriazoles to hydrolysis has been studied.
The insertion of sulfur and selenium into the 1,2‐dihydrophosphete ring
Authors: Huy Ngoc Hoa Tran , Mathey François
Published: January 2005

Sulfur and selenium react with a 1,2‐dihydrophosphete P‐W(CO)5 complex at ca. 120°C to give the corresponding 2,5‐dihydro‐1,2‐thiaphosphole and 2,5‐dihydro‐1,2‐selenaphosphole complexes, respectively. These products result from an insertion of S or Se into the PC sp3 bond of the four‐membered ring.
Persulfuration of phosphinines: Synthesis and X‐ray crystal structure analysis of a P2S3 derivative
Authors: Holand Serge , Alcaraz Jean‐Marie , Ricard Louis , Mathey François
Published: January 2005

The reaction of 4,5‐dimethyl‐2‐phenylphosphinine with sulfur in boiling benzene in the presence of N‐methylimidazole as a catalyst first yields a P‐sulfide. This monosulfide further reacts with sulfur to give a diphosphinine trisulfide and a diphosphinine tetrasulfide. The X‐ray crystal structure analysis of the trisulfide has been carried out.

The two head‐to‐tail 1,6‐dihydrophosphinine rings are connected by PSC and PC links, thus forming a central 1,2,4‐thiadiphospholane heterocycle. The PC bridge is weak [1.881(3) Å] and sulfur can insert into it to give the symmetrical tetrasulfide with two PSC bridges.
Tellurium tetrachloride: Addition to cyclohexene and preparation from tellurium dioxide and trimethylchlorosilane
Authors: Fukuzawa Shin‐Ichi , Irgolic Kurt J. , O'Brien Daniel H.
Published: January 2005

Tellurium dioxide, trimethylchorosilane, acetyl chloride, or acetyl bromide in glacial acetic acid generated a homogeneous solution. Addition of cyclohexene produced trans‐2‐halocyclohexyl tellurium trihalides of excellent purity in 70% yield. With dichloromethane or ethanol‐free chloroform the same compounds were obtained from heterogeneous reaction mixtures. trans‐2‐Methoxycyclohexyl tellurium trichloride was obtained quantitatively from tellurium dioxide, trimethylchlorosilane, and cyclohexene in absolute methanol. In the absence of cyclohexene, tellurium tetrachloride was obtained in 91% yield from tellurium dioxide and trimethylchlorosilane in chloroform, and tellurium tetrabromide in 98% yield from tellurium dioxide and acetyl bromide in glacial acetic acid.
Facile synthesis of 2,4‐dienals via an arsonium salt and its application to some natural products
Authors: Yang Jian‐Hua , Shi Li‐Lan , Xiao Wen‐Juan , Wen Xue‐Qing , Huang Yao‐Zeng
Published: January 2005

2,4‐Dienals were synthesized conveniently by using a new formylenylolefination method. The aldehydes were reacted with formylallyltriphenylarsonium bromide (2) in Et2OTHFH2O (9 : 1 : 0.05) in the presence of K2CO3 at room temperature to give (2E,4E)‐and (2E,4Z)‐dienals, in favor of the former. They could be easily separated by chromatography, and the latter, in CH2Cl2, could be converted to the former on treatment with a catalytic amount of iodine in daylight. The configurations of the (E,E) products have been conveniently identified by 1H NMR determined in C6D6. The syntheses of two natural products, navenone A and Otanthus maritima amide, by this method are also reported in detail.
Diketones from ozonolysis of fused 3‐phospholene oxides: Cyclizations to 3‐phosphorinone and to 1,4‐dihydro‐1,4‐azaphosphinine derivatives
Authors: Quin Louis D. , Marsi Brian G.
Published: January 2005

1‐R‐3‐Methyl‐2,4,5,6,7,7a‐hexahydro‐1(H)‐phosphindole 1‐oxide and 1‐R‐3‐methyl‐6‐methoxy‐2,8,9,9a‐tetrahydro‐1(H)‐benzo[e]phosphindole 1‐oxide (R = Me or Ph) were prepared and ozonized at −78°C to give diketones in good yield. The intramolecular aldol condensation was performed on certain of these ketones to give multicyclic 3‐phosphorinone derivatives. In some cases, double‐bond rearrangement into the ring‐fusion position was encountered. The 1‐phenyl derivative in the benzophosphindole series could not be cyclized due to ready displacement of the P fragment from the tetralone system. The diketones reacted with ammonium acetate to give multicyclic derivatives of the 1,4‐dihydro‐1,4‐azaphosphinine ring system. 1,2,3,4,5,6,7,8‐Octahydro‐3‐oxo‐1‐phenylphosphinoline 1‐oxide was used to demonstrate the value of the bicyclic 3‐phosphorinones as precursors of 1‐phosphadecalone derivatives. The carbonyl group was protected as the ethylene ketal and the double bond (as well as the benzene ring) was hydrogenated with ease. Hydrolysis gave the 1‐phospha‐3‐decalone derivative. Reduction of the same 3‐phosphorinone with NaBH4 gave a mixture of diastereomeric alcohols.
(R,R)‐2,3‐Butanediol and (s)‐pinanediol allylboronates in chiral synthesis of (2S,3S)‐3‐methyl‐5‐hexen‐2‐ol
Authors: Matteson Donald S. , Campbell J. Douglas
Published: January 2005

(R,R)‐Butanediol (dichloromethyl)boronate (1) with 1 equiv. allylmagnesium halide yields (R,R)‐2,3‐butanediol (1S)‐(1‐chloro‐3‐butenyl)boronate (3) together with the diallylated product (R,R)‐2,3‐butanediol (1‐allyl‐3‐butenyl)boronate (4). The formation of 4 is unprecedented in reactions of α‐chloroboronic esters with Grignard reagents. With methylmagnesium bromide 3 yielded (R,R)‐2,3‐butanediol (1S)‐(1‐methyl‐3‐butenyl)boronate (5), which failed to hydrolyze with water. Hydrolysis of 3 yielded impure α‐chloroboronic acid, which was esterified with pinacol and treated with methylmagnesium bromide to form 6, which with (dichloromethyl)lithium followed by methylmagnesium bromide yielded diastereomeric boronic esters 7 and 8. Oxidation by hydrogen peroxide yielded (2S,3S)‐ and (2R,3S)‐3‐methyl‐5‐hexen‐2‐ol (9 and 10, ees unknown). Treatment of (s)‐pinanediol allylboronate (11) with (dichloromethyl)lithium at −100°C followed by zinc chloride at up to 25°C has proceeded in the normal way to form (s)‐pinanediol (1S)‐(1‐chloro‐3‐butenyl)‐boronate (12), which has been elaborated via 13, 14, and 15 to (2S,3S)‐3‐methyl‐5‐hexen‐2‐ol (9) in 95% de.
Reaction of the diisopropylaminochlorophosphenium cation with crotonaldehyde dimethylhydrazone and acetone azine
Authors: Arif Atta M. , Cowley Alan H. , Kren Robert M. , Westmoreland Donald L.
Published: January 2005

The phosphenium ion [(i‐Pr2N)CIP]+ (1) reacts with crotonaldehyde dimethylhydrazone (2) to afford a product with a C3NP ring system (4). The reaction of 1 with acetone azine (3) results in a novel tricyclic compound (6) which features a C2N2P2 and two C2N2P rings. The structures of 4 and 6 were established by X‐ray crystallography. Compound 4, C12H26AlCl3N3OP, crystallizes in the monoclinic space group P21/n with Z = 4, a = 15.400(6), b = 14.442(4), c = 9.206(3) Å, and β = 93.33(3)°. Compound 6, C12H22Al2Cl6N4O2P2, crystallizes in the triclinic group P1 with Z = 1, a = 8.556(1), b = 9.782(1), c = 8.119(1) Å, α = 94.48(1), β = 104.97(1), and γ = 78.35(1)°.
About the structure of phosphorus ylids: Electron distribution and geometry
Authors: Schlosser Manfred , Jenny Titus , Schaub Bruno
Published: January 2005

Using 13C‐chemical shifts as a probe for the electronic environment of carbon centers, triphenylphosphoniomethanide, the model case of a “reactive” phosphorus ylid, was found to have much more zwitterion than PC double bond character (resonance structure 1a being dominant). Triphenylphosphonio‐propenide (“triphenylphosphonium‐allylid”), a “moderated” ylid, accumulates electron excess mainly at the α‐carbon atom (resonance structure 6a being dominant) whereas triphenylphosphonio‐ethenoate (formyl‐methylene‐triphenylphosphorane) and other “stabilized” ylids carry roughly equal fractions of negative charge at the α‐carbon and the oxygen atom (resonance formulas a and b being of comparable importance). The one‐bond C,H coupling constant of triphenylphosphonio‐methanide (1) argues against a perfectly planar ylid center. The three‐bond P,C coupling constants permit the assignment of endo‐ or exo‐configurations to ylids having an allyl‐type side‐chain.
Stereochemistry in the reaction of alkylsulfinyl phenylmethyl carbanion with electrophiles
Authors: Higaki Masato , Goto Mutsuo , Ohno Atsuyoshi
Published: January 2005

Stereochemistry of the reactions of methyl‐, ethyl‐, 2‐propyl‐, and 1,1‐dimethylethylsulfinyl phenylmethyl carbanions with deuterium oxide and methyl iodide in tetrahydrofuran have been studied. The 2‐propylsulfinyl phenylmethyl carbanion exerts abnormal behavior in the sense that the alkyl substituent herein has no ability to freeze the conformation of the carbanion. The results are interpreted in terms of hard and soft interactions. 7Li and 17O nuclear magnetic resonance (NMR) spectroscopy revealed that the carbanions derived from these sulfoxides behave as the oxylate form.
[1,5] Sigmatropic shifts in a 1,4‐diphospholylbenzene
Authors: Mercier François , Mathey François
Published: January 2005

The central phenylene ring of 1,4‐bis(3,4‐dimethylphosphol‐1‐yl)benzene undergoes [1,5] shifts around both phospholyl rings above 150°C to give 1,4‐bis(3,4‐dimethyl‐5H‐phosphol‐2‐yl)benzene, which can be trapped by tolane, [CpFe(CO)2]2, or Mn2 (CO)10 to yield the corresponding bis‐1‐phosphanor‐bornadiene, bis‐phosphaferrocene, or bis‐phosphacymantrene respectively.
Ligand coupling of 2‐pyridyl sulfoxides having an sp2 stereocenter at the α‐position: A novel preparation of α‐stilbazoles
Authors: Wakabayashi S. , Kiyohara Y. , Kameda S. , Uenishi J. , Oae S.
Published: January 2005

Ligand coupling of (E)‐ and (Z)‐styryl 2‐pyridyl sulfoxides with methylmagnesium bromide gave (E)‐and (Z)‐2‐styrylpyridine, respectively in a stereospecific manner. A number of (E)‐2‐styrylpyridine derivatives were prepared by the coupling reaction. Methyl styryl sulfoxide and 2,2′‐bipyridyl were obtained as by‐products. The mechanism of the reaction is discussed based on quantitative analysis of the products.
A novel simple dethioacetalization of thioacetals and thioketals with t‐butyl thionitrite
Authors: Park Young Jun , Kim Yong Hae , Oae Shigeru
Published: January 2005

Thioacetals and thioketals were readily cleaved to carbonyl compounds in excellent yields by treatment with t‐butyl thionitrite at ca. 0°C in acetonitrile under mild conditions. The conversion of thioketals to the ketones appears to be initiated via nitrosation on two sulfur atoms of the thioketals, followed by intramolecular transfer of nitroso oxygen.
X‐ray structure of 3‐diphenylmethylene‐2‐(2,4,6‐tri‐t‐butylphenyl)thiaphosphirane 2‐sulfide: The first thiaphosphirane with exo‐methylene
Authors: Hirotsu Ken , Okamoto Akihiro , Toyota Kozo , Yoshifuji Masaaki
Published: January 2005

The title compound was prepared by sulfurization of a 1‐phosphaallene and its x‐ray structure analysis showed the following notable features of the thiaphosphirane ring: P‐S = 2.101(2), P‐C = 1.770(5) and S‐C = 1.767(5) Å (remarkably short), and ∠SPC = 53.5(2), ∠PSC = 53.6(2) and ∠PCS = 72.9(2)°.
Toxic organophosphorus esters hydrolysis enhanced by onium perborates
Authors: Cristau Henri‐Jean , Torreilles Eliane , Ginieys Jean‐François
Published: January 2005

The addition of equimolecular quantities of phosphonium salts to an aqueous sodium perborate solution (Na+ PB−) greatly enhances he efficiency of Na+ PB− as a reagene that destroys organophosphorus esters, such as p‐nitrophenyldiethyl phosphate or ethyl p‐nitrophenyl methylphosphonate.
Pyrromethene–BF2 complexes as laser dyes:1.
Authors: Shah Mayur , Thangaraj Kannappan , Soong Mou‐Ling , Wolford Lionel T. , Boyer Joseph H. , Politzer Ieva R. , Pavlopoulos Theodore G.
Published: January 2005

Condensations between 3‐X‐2,4‐dimethylpyrroles (X = H, CH3, C2H5, and CO2C2H5) and acyl chlorides gave derivatives of 3,5,3′,5′‐tetramethylpyrromethene (isolated as their hydrochloride salts): 6‐methyl, 6‐ethyl, 4,4′,6‐trimethyl, 4,4′‐diethyl‐6‐methyl, and 4,4′‐dicarboethoxy‐6‐ethyl derivatives for conversion on treatment with boron trifluoride to 1,3,5,7‐tetramethylpyrromethene–BF2 complex (TMP–BF2) and its 8‐methyl (PMP–BF2), 8‐ethyl, 2,6,8‐trimethyl (HMP–BF2),2,6,‐diethyl‐8‐methyl (PMDEP–BF2), and 2,6‐dicarboethoxy‐8‐ethyl derivatives. Chlorosulfonation converted, 1,3,5,7,8‐pentamethylpyrromethene–BF2 complex to its 2,6‐disulfonic acid isolated as the lithium, sodium (PMPDS–BF2), potassium, rubidium, cesium, ammonium, and tetramethylammonium disulfonate salts and the methyl disulfonate ester. Sodium 1,3,5,7‐tetramethyl‐8‐ethylpyrromethene‐2,6‐disulfonate–BF2 complex was obtained from the 8‐ethyl derivative of TMP–BF2. Nitration and bromination converted PMP–BF2 to its 2,6‐dinitro‐(PMDNP–BF2) and 2,6‐dibromo‐ derivatives. The time required for loss of fluorescence by irradiation from a sunlamp showed the following order for P–BF2 compounds (10−3 to 10−4 M) in ethanol: PMPDS–BF2, 7 weeks; PMP–BF2, 5 days; PMDNP–BF2, 72 h; HMP–BF2, 70 h; and PMDEP–BF2, 65 h. Under similar irradiation PMPDS–BF2 in water lost fluorescence after 55 h. The dibromo derivative was inactive, but each of the other pyrromethene–BF2 complexes under flashlamp excitation showed broadband laser activity in the region λ 530–580 nm. In methanol PMPDS–BF2 was six times more resistant to degradation by flashlamp pulses than was observed for Rhodamine‐6G (R‐6G). An improvement (up to 66%) in the laser power efficiency of PMPDS–BF2 (10−4 M in methanol) in the presence of caffeine (a filter for light <300 nm) was dependent on flashlamp pulse width (2.0 to 7.0 μsec).
Complexes of tricoordinate hypervalent pnictogens with pentamethylcyclopentadienylruthenium
Authors: Arduengo Anthony J. , Lattman Michael , Calabrese Joseph C. , Fagan Paul J.
Published: January 2005

The complexes of a pentamethylcyclopentadienylruthenium moiety with hypervalent tricoordinate pnictogens are reported. A unique mode of complexation is observed for each of the different pnictogens (P, As, Sb). The phosphorus derived complex exhibits an 8‐electron tetrahedral bonding environment at phosphorus. The antimony derived complex maintains a 10‐electron bonding system at antimony with a pseudo‐trigonalbipyramidal geometry at antimony. The arsenic‐containing complex is formed with destruction of the original arsenic heterocycle and formation of a trinuclear Ru–Ru–As ring. Remarkably, the formation of the arsenic ruthenium complex can be reversed to reconstruct the original arsenic heterocycle.
Selenium‐Catalyzed debromination of vic‐dibromoalkanes and α‐bromo ketones with carbon monoxide and water
Authors: Nishiyama Yutaka , Katsuen Susumu , Jounen Hiroshi , Hamanaka Sawako , Ogawa Akiya , Sonoda Noboru
Published: January 2005

Selenium has been found to be an excellent catalyst for the reductive debromination of some organic bromides with carbon monoxide and water: vic‐dibromoalkanes and α‐halo ketones can be reduced to the corresponding alkenes and ketones respectively in moderate to high yields.
Synthesis of dimeric 1,3,2λ5‐benzoxazaphospholes from phosphinic acid derivatives by silylation/desiloxylation
Authors: Bovin Alexander N. , Yarkevich Alla N. , Tsvetkov Eugene N.
Published: January 2005

The reaction of N,N,O‐tris(trimethylsilyl)‐o‐aminophenol with two equivalents of phosphinic chloride yielded dimeric 2,2‐disubstituted 1,3,2λ5‐benzoxazaphospholes and trimethylsilyl phosphinate. The chlorides having the bulk substituents (o‐chlorophenyl or tert‐butyl) at phosphorus or containing PN and PO bonds (instead of a PC bond) either didn't react at all or reacted to retain the phosphoryl group. Being stable in solution at 20°C, the individual diastereoisomers of dimeric 1,3,2‐benzoxazaphospholes were converted upon warming to an equilibrium mixture of isomers. When reacted with another dimer each gave a mixed dimeric compound having two different phosphorus atoms in the molecule.
Bis(diisopropylamino)phosphanyldiazomethane: A building block for the synthesis of stable carbene and nitrilimines
Authors: Bertrand Guy
Published: January 2005

Thermolysis of [bis(diisopropylamino)phosphanyl](trimethylsilyl)diazomethane 1 affords the corresponding carbene 2, which is stable enough to be spectroscopically characterized. This species possesses a phosphorus–carbon multiple‐bond character as shown by the 2 + 3 and 2 + 2 cycloaddition reactions observed with trimethylsilyl azide or N2O and ethyl cyanoformate, respectively. On the other hand, 2 undergoes all the classical reactions of a carbene: cyclopropanation reaction with electron‐poor alkenes, carbon–hydrogen bond insertion, and carbene–carbene coupling with isonitriles. Compound 2 reacts with trimethylsilyl triflate affording a stable methylenephosphonium salt 15. Treatment of the lithium salt of the [bis(diisopropylamino)thiophosphoranyl]diazomethane 18 with the bis(diisopropylamino)phosphanyl chloride leads to a stable nitrilimine 3. Thermolysis of 3 affords the isomeric diazo derivative 20, while photolysis gives rise to thiophophoranylnitrile 21 and cyclodiphosphazene 23. Regioselective 2 + 3 cycloadditions are observed with electron‐poor dipolarophiles. Addition of trimethylsilyl triflate to 3 leads to a stable electrophilic nitrilimine 29.
Polyazaphosphorus macrocycles: Synthesis, reactivity, complexation
Authors: Majoral Jean‐Pierre , Badri Meryam , Caminade Anne‐Marie
Published: January 2005

A general synthesis of various polyazaphosphorus macrocycles involving [1 + 1], [2 + 2], or [3 + 3] cyclocondensations is reviewed, as well as the attempted synthesis of cryptands. Selective reduction (imino functions) methylation (PS groups), silylation (PO groups) are reported. Preparations of some macrocycle complexes are described.
Chemistry of the 2,3‐oxaphosphabicyclo[2.2.2]octene ring system: Extrusion of metaphosphates
Authors: Quin Louis D. , Bodalski Ryszard , Jankowski Stefan , Quin GyöOungyi S. , Sadanani Narayan D. , Wu Xiao‐Ping
Published: January 2005

The 2,3‐oxaphosphabicyclo[2.2.2]octene 3‐oxide (or sulfide) ring system is of considerable value because it easily fragments on being heated or irradiated (254 nm) to provide three‐coordinate phosphoryl species. The system is synthesized by O‐insertion with peracids into a CP bond of 7‐phosphanorbornene derivatives with a variety of P‐substituents. With rare exception, the insertion has been found to proceed with retention of the configuration at phosphorus, as established by X‐ray and NMR techniques. The thermal fragmentation that produces the metaphosphate derivatives EtOPO2, EtOP(S)O, and Et2NPO2 follows first‐order kinetics, and is independent of the concentration of a trapping agent for these species. Solvent effects and activation parameters join in defining a retrocycloaddition mechanism that ejects the free metaphosphate. The species PhPO2 can also be easily generated either thermally or photochemically. Metaphosphates have been found to attack ethereal oxygen in epoxides and oxetanes, and may undergo anchimeric participation with a properly placed methoxy group on the substituent used in the 2,3‐oxaphosphabicyclo[2.2.2]octene precursor.
Optically active phosphine oxides: 10 [1]; X‐ray structure and conformation of (Sp)‐ and (Rp)‐L‐menthyl α‐(phenylvinylphosphinyl)acetates
Authors: Pietrusiewicz K. Michał , Zabłocka Maria , KuoáZnikowski Maciej , Wieczorek Wanda , Maniukiewicz Waldemar , Rospenk Maria
Published: January 2005

The structures and solid‐state stereochemistry of the two P‐epimeric compounds (1 and 2) formed in a reaction of butyl phenylvinylphosphinite with (‐)‐L‐menthyl bromoacetate were studied by X‐ray crystallography and CP–MAS 13C NMR spectroscopy. The two compounds were also analyzed in solution by means of 2D 1H NMR, 13C NMR, IR, UV, and dipole moment measurement techniques. Compound 1, C20H29O3P, crystallized in the orthorhombic group P 212121 with Z = 4, a = 20.491(2), b = 16.719(1), and c = 5.910(1). Compound 2, C20H29O3P, crystallized in the monoclinic space group P 21 with Z = 2, a = 9.266(1), b = 9.852(1), c = 10.954(1), and β = 95.20(1)°. In the crystals both compounds possess their CCPO fragments in an s‐cis array, and have their PO and CO dipoles oriented uniformly in a syn, nearly parallel, fashion. In solution, however, an anti arrangement of these two dipoles is slightly preferred.
Synthesis of glycosyl phosphonates and related compounds
Authors: Vasella Andrea , Baudin Gisèle , Panza Luigi
Published: January 2005

The synthesis of glycosylphosphonates, isopolar, nonisosteric analogues of glycosylphosphates, from halonitro ethers, glycosyl acetates, or glycosyl trichloroacetimidates is reviewed. A new approach to phosphonate analogues of myo‐inositol trisphosphate (50) is described. Based on a hypothetical reaction mechanism for the formation of thioethers from a glyoxalase I inhibitor, an advanced intermediate 59 for the synthesis of diphosphonate–phosphate analogues of 50 is obtained by an addition–elimination–addition sequence from 54. Finally, glucosylphosphines, characterized as the corresponding phosphine oxides 61 and 62 have been prepared from the glycosylidene diazirine 60, a precursor of the tetra‐O‐benzylglucopyranosylidene carbene. The phosphine oxides 61 and 62 were also obtained by reaction of the glycosyl acetate 18 with methyl diphenylphosphinite.
Synthesis of antisense oligodeoxyribonucleotide analogues by use of deoxyribonucleoside 3′‐bis(1, 1, 1, 3,3,3‐hexafluoro‐2‐propyl) phosphites as new key intermediates
Authors: Hosaka Hideo , Watanabe Testuo , Suzuki Yoshikazu , Takaku Hiroshi
Published: January 2005

The deoxyribonucleoside 3′‐bis(1,1,1,3,3,3‐hexafluoro‐2‐propyl) phosphite units (3) are used in the chemical synthesis of oligodeoxyribonucleotides on solid supports. The new phosphite units (3) were prepared easily by reaction of nucleosides and tris‐(1,1,1,3,3,3‐hexafluoro‐2‐propyl) phosphite (2). They are readily activated by N‐methylimidazole under very mild conditions on a solid support. This operation involves a one step reaction, which is an advantage over both the phosphite and H‐phosphonate approaches. The use of deoxyribonucleoside phosphite intermediates in the synthesis of antisense oligodeoxyribonucleotides is also described.
Iminophosphanes as pseudocarbenes: A theoretical study of product formation
Authors: Schoeller Wolfgang W. , Busch Thilo , Niemann Jürgen , Dabisch Thomas , Stohrer W.‐D.
Published: January 2005

P(III) double bond systems possess two closely spaced frontier orbitals, a π‐orbital and a σ‐orbital. In the parent iminophosphane the orbital sequence is σ (HOMO) and π* (LUMO). Thus, it is isolabal to a singlet carbene and undergoes self‐dimerization via a [2 + 1] cycloaddition. The resulting three membered ring system can be considered as a complex of two iminophosphanes. Contrary to the classical cyclopropanation reaction, in the pseudo‐carbene iminophosphane the corresponding [2 + 1] reaction is only slightly exothermic, as established by ab initio calculations at the SCF/CEPA‐1 and the MCSCF/ACPF level.
Role of the conformation in the reactivity of 1,3‐diphosphapropenes
Authors: Gouygou Maryse , Koenig Max , Escudié Jean , Couret Claude
Published: January 2005

The symmetrical and unsymmetrical 1,3‐diphospha‐propenes 3 and 4 were obtained from the corresponding diposphiranes 1 and 2. The chemical behavior of these compounds has been studied. Phosphonium‐phosphaalkenes 7a and 10a have been obtained in the reactions with aluminium trichloride. Whereas the symmetrical diphosphaallene 13 can be obtained by reaction of 1 or 3 with lithio compounds, the unsymmetrical diphosphaalene 14 cannot be prepared by a similar route. Reduction of 3a and 4a (obtained with a different conformation) by lithium aluminum hydride afforded phosphino‐phosphaalkenes 17a and 18a (with a similar conformation); further dehydrochlorination with amines led to the symmetrical and unsymmetrical diphosphaalenes 13 and 14, respectively. The formation of allenes strongly depends on the conformation of the starting diphosphapropenes.
Use of 1,3‐diphosphacyclobutadiene complexes in the synthesis of mixed metal aggregates containing cobalt, rhodium, and platinum: Structure of a hexarhodium complex
Authors: Hitchcock Peter B. , Maah Mohd Jamil , Nixon John F.
Published: January 2005

The η4‐diphosphacyclobutadiene complexes [M(η5‐C5R5)(η4‐P2C2Bu)] (M  Co, Rh; R  H, Me), react with Rh(I), Pt(O), and Pt(II) centers via the phosphorus lone paris of the rings of afford mixed metal complexes. The crystal and molecular structure of the novel hexarhodium complex [Rh2Cl2{Rh(P2C2Bu)}]4 (Cp  N5‐C5H5) is presented and discussed.
Diels‐Alder adducts of 4‐chloro‐1,6‐dihydrophosphinine derivatives: A new precursor of 2‐phosphapropene
Authors: Quin Louis D. , Tang Jian‐Sheng , Keglevich György
Published: January 2005

The 4‐chloro‐1,6‐dihydrophosphinine derivatives, prepared as a mixture of 3‐ and 5‐methyl isomers from the thermolysis of dichlorocarbene adducts with 1‐R‐3‐methylphospholene oxide (R  Me, MeO, EtO, n‐PrO, i‐PrO), participate in Diels‐Alder reactions with dimethyl acetylenedicarboxylate and N‐phenylmaleimide. The former reactant is of special value since the 2‐phosphabicyclo[2.2.2]octa‐5,7‐diene framework is thermally labile and undergoes retrocycloaddition by a different path, eliminating the CP bridging unit as a low‐coordinate species. Thus, in the case of R  Me, the initial phosphine oxides (a mixture of isomers) have been reduced to the phosphines and these undergo straightforward fragmentations on heating at 50°C to produce 2‐phosphapropene. The reactions of this transient species with water and alcohols have been investigated. Unlike the case of stabilized phosphaalkenes, hydration occurs smoothly without catalysis to produce Me2P(O)H; addition of alcohols gives phosphinites, Me2POR. The structure of the Diels‐Alder adducts was confirmed by 31P, 1H, and 13C NMR spectroscopy. Each of the isomeric 1,6‐dihydrophosphinine oxides gives two diastereomeric adducts; partial separation of some of the resulting four‐component mixtures was achieved with silica gel chromatography.
Dense compounds of C, H, N, and O atoms: Nitramine derivatives of diimino‐ and dioxodecahydro‐1 h,5h‐diimidazo‐[4,5‐b:4′,5′‐e]pyrazine
Authors: Vedachalam Murugappa , Ramakrishnan Vayalakkavoor T. , Boyer Joseph H.
Published: January 2005

Guanidine condensed with 1,4‐diformyl‐2,3,5,6‐tetrahydroxypiperazine 1 to give 2,6‐diiminodecahydro‐1H,5H‐diimidazo[4,5‐b:4′,5′‐e]pyrazine 3 isolated as the tetrahydrochloride salt. nitric acid (100%) at −40°C converted the bisguanidine 3 to 2,6‐dinitrimino‐4,8‐dinitrodecahydro‐1H,5H‐diimidazo[4,5‐b:4′,5′‐e]‐ pyrazine 8 isolated as a dihydrate, whereas nitration by nitronium tetrafluoroborate at 0° to 25°C afforded 2,6‐diimino‐4,8‐dinitrodecahydro‐1H,5H‐diimidazo[4,5‐b:4′,5′‐e]pyrazine 9 isolate as the monohydrated bistetrafluoroborate salt, and treatmetn with nitric acid (100%) and acetic anhydride or phosphorus pentoxide converted the bisguanidine 3 to 2,6‐dioxo‐1,3,4,5,7,8‐hexanitrodecahydro‐1H,5H‐diimidazo[4,5‐b:4′,5′‐e]pyrazine 4, also obtained from the tetra N‐nitro compound 8 · 2 H2O and from the dinitramine 9 · 2 BHF4 · H2O after similar treatment. The cis‐syn‐cis‐ configuration of the tricyclic bisurea 4 and bisguanidine 9 was confirmed by X‐ray crys‐tallographic analysis. Nitrosation by nitrous acid or by dinitrogen tetroxide converted the bisguanidine 3 to a hydrated 2,6‐dinitrosimino‐4,8‐dinitrosodecahydro‐1H,5H‐diimidazo[4,5‐b:4′,5′‐]pyrazine 10 · 2.5 H2O, whereas treatment with nitrosonium tetrafluo‐roborate afforded the bistetrafluoroborate salt of 4,8‐dinitroso derivative 11 · 2 BHF 4. The nitrosamines 10 and 11 were converted to the tetranitro compound 8 · 2 H2O on treatment with nitric acid (100%) at −40°C. Treatmnt with fluoroboric acid etherate in acetonitrile converted nitroimino groups in compound 8 · 2 H2O and nitrosimino groups in compound 10 · 2.5 H2O to imino groups in compounds 9 · 2 BHF2 · H2O and 11 · 2 HBF4 respectively.
Stereochemistry and some synthetic uses of the heteroarylation of phospholes
Authors: Deschamps Eliane , Ricard Louis , Mathey François
Published: January 2005

Further studies have been conducted on the condensation of electron‐rich arenes or heteroarenes with the dienic system of phosphole P‐complexes. According to the X‐ray crystal structure analysis of one of the resulting 2‐aryl‐3‐phospholene P‐complexes, the condensation takes place on the side of the diene opposite to the complexing group. The decomplexation of the phospholene P–Mo(CO)5 and P–W(CO)5 complexes, respectively, by reaction with sulfur or halogens and tertiary amines yields the corresponding P‐sulfides and oxides with full retention of the stereochemistry at phosphorus. Double condensation of the phosphole P‐complexes onto the 2 and 5 positions of thiophene and furan ultimately leads to phosphole–thiophene–phosphole and phosphole–furan–phosphole chains. The first type has been characterized by X‐ray crystal structure analysis of its P,P‐disulfide. No electronic delocalization appears to take place along the chain.
Trifluoromethyl phosphaalkenes of the type F3CPC(OR)NR2: Synthesis, spectroscopic investigations, and ligand properties [1]
Authors: Grobe Joseph , Van Duc Le , Althoff Ulrike , Krebs Bernt , Dartmann Mechtild , Gleiter Rolf
Published: January 2005

The one‐pot reaction of the alcohol adducts F3CP(H)CF2OR of perfluoro‐2‐phosphapropene with secondary amines in a 1:3 molar ratio affords the stable phosphaalkenes F3CPC(OR)NR2 (R = Me, Et) 1–4 in yields of 58%. NMR and He(I) PE spectroscopic investigations show that the lone pair electrons on nitrogen and oxygen participate in n/π conjugation. In contrast to typical low‐coordinated double bonds the new derivatives do not react with alcohols, amines, and 1,3‐dienes. The derivatives are more closely related to the phosphaalkenes F3C(F)NR2 than to perfluoro‐2‐phosphapropene. The reaction of F3C(OEt)NMe2 (3) with Cr(CO)5THF yields the η1(P) complex Cr(CO)5[F3CPC(OEt)NMe2] (7) with an unusually long sp2 PC bond (1.809 Å).
Theoretical study on the transition state of oxaphosphetane formation between ethylidenetriphenylphosphorane and acetaldehyde
Authors: Yamataka Hiroshi , Hanafusa Terukiyo , Nagase Shigeru , Kurakake Toshiya
Published: January 2005

The MNDO MO calculations were carried out for the formation of oxaphosphetanes from substituted ylides and aldehydes (Equations 2–4). It was found that the reactions proceed through a nearly planar cyclic four‐membered ring transition state (TS) in all cases studied and that phenyl substitution on phosphorus has little effect on the TS geometry. This finding is not in line with the TS models that have been proposed to explain the experimentally observed cis‐selectivity.
Azidophosphanes: Attractive starting materials for the preparation of phosphazenes
Authors: Riesel Lothar , Friebe Robert , Bergemann Anke , Detlef/Sturm
Published: January 2005

Azidophosphanes are versatile reactants in the Staudinger reaction. The azides Cl2PN3 (1), (Et2N)ClPN3 (2), and (Et2N)2PN3 (3) react with phosphanes to give the N‐phosphanyl phosphazenes 4–10. (Et2N)P(N3)2 is oxidized by PhN3 yielding (Et2N)P(N3)2NPh (11), which with PPh3 yields the di‐ and triphosphazenes 12 and 13.
The structures of the hypho‐compounds B5H and B6H14: Application of the combined ab initio/IGLO/NMR method
Authors: Bühl Michael , Schleyer Paul Von Ragué , McKee Michael L.
Published: January 2005

Ab initio and NMR chemical shift (IGLO) calculations on the TZP/MP2/6‐31G* level suggest a Cs (1c), or the closely related C1 (1d) structure, rather than the proposed C2v (1a) geometry for hypho‐B5H12−. The two equivalent Cs forms interconvert rapidly with a barrier of ca 5 kcal/mol. For hypho‐B6H14 (2), at least six isomers examined lie within ca 7 kcal/mol in energy suggesting fluxional behavior, but none of the geometries (including the current proposals in the literature) reproduces the experimental chemical shifts.
Solid‐state conformations of medium‐sized‐ring phosphorus heterocycles: Preparation and x‐ray crystal structure of a benzo‐fused 1,3,2‐dioxaphosphepane in a twist conformation
Authors: Setzer William N. , Brown Milton L. , Wu Chia‐Kuei , Meehan Edward J.
Published: January 2005

The crystal and molecular structure of the benzo‐fused seven‐membered‐ring phosphorus heterocycle, 2‐phenyl‐2‐oxo‐5,6‐benzo‐1,3,2‐dioxaphosphepane, has been determined by single‐crystal X‐ray techniques. The compound crystallizes in the monoclinic space group P21/c with four molecules per unit cell of dimensions a = 13.312(1) Å, b = 7.6132(8) Å, c = 12.119(2) Å, and β = 95.990(9)°. Full‐matrix leastsquares refinement led to R = 4.4% and Rw = 5.9%. The conformation adopted by the 1,3,2‐dioxaphosphepane ring is a twist with approximate C2 symmetry.
Edge inversion in tricoordinated main group IV anions
Authors: Dixon David A. , Arduengo Anthony J. , Lappert Michael F.
Published: January 2005

The inversion barriers for SiF3−, GeF3−, SnF3−, SnCl3−, and SnCl2NH2− have been calculated by ab initio molecular orbital theory with large basis sets and have included the effects of electron correlation. The anions are predicted to invert by the edge inversion process. The edge inversion barriers in kcal/mol are 40.3, 34.3, 27.8, 27.8, and 14.2 in the order given above. Geometric effects and the charge distributions are discussed.
Reaction of thioxophosphorane sulfenyl bromides with ethyl vinyl ether: Mechanistic and synthetic aspects
Authors: Potrzebowski Marek J. , Łopusiński Andrzej , Michalski Jan
Published: January 2005

The mechanistic and synthetic aspects of the addition reaction of thioxophosphorane sulfenyl bromide with ethyl vinyl ether were studied in detail by NMR techniques. It has been found that the regiospecific, primary product of the reaction, 1‐bromo‐1‐ethoxy‐2S(dialkoxythiophosphoryl)ethane I, is unstable and undergoes slow decomposition to give four compounds. The formation of thiophosphoryl derivatives, vinyl ethers II and III, aldehyde IV, and the symmetrical hemiacetal anhydride V, has been considered in terms of a carbocation intermediate. By choice of the appropriate reaction conditions, the aldehyde IV can be obtained in very high yield.
Stereochemistry of the reaction of ribonucleoside cyclic 3′,5′‐phosphorothioates with oxiranes
Authors: Okruszek Andrzej , Guga Piotr , Stec Wojciech J.
Published: January 2005

The stereochemical course of the epoxide‐induced oxidative rearrangement of ribonucleoside cyclic 3′,5′‐phosphorothioates into the corresponding 2′,3′‐phosphates has been determined using styrene [18O] oxide and (Sp)‐uridine cyclic 3′,5′‐phosphorothioate. The evidence of full stereoselectivity of this reaction is presented and mechanistic implications of the presence of the nucleoside 2′‐hydroxyl group are discussed in terms of a classical Hamer Mechanism.
Directed ortho‐lithiation reactions: Position‐specific introduction of tributylstannyl derivative onto β‐[N,N‐dimethylamino]ethoxybenzenes
Authors: El‐Wakil Hoda , Seitz Daved E. , Mansour El‐Sayed M. E.
Published: January 2005

This article presents the position‐specific introduction of substituents onto substituted phenolic rings via electrophilic destannylation of trialkylstannyl derivatives of β‐[N,N‐dialkylamino]ethoxybenzenes.
Recent developments in heterocyclic systems with a Si–M′–Ge or Ge–M′–Ge linkage (M′ = Fe, Ru, or Co)
Authors: Barrau Jacques
Published: January 2005

The present review describes recent work on the synthesis, spectroscopic analysis, and investigation of the chemical behaviors of new polynuclear heterocyclic complexes 1–7 having M–M′–M catenation. Various CO substitution, cleavage, expansion, and adducts decomposition reactions are described.
OAs(NMe2)3: Synthesis and crystal structure of the arsenic analogue of HMPT
Authors: Lorberth JÖRg , Dorn Reiner , Shin Sung‐Hee , Otto Michael , Massa Werner
Published: January 2005

OAs(NMe2)3 (HMAsT) is obtained in low yields by reacting OAsCl3 with excess HNMe2 or by ozonolysis of As(NMe2)3; however, it is formed in yields >65% by using (Me3Si)2O2 and As(NMe2)3 in hydrocarbon solution. The structure of HMAsT was established by IR/Raman, NMR and mass spectroscopy, and single crystal X‐ray structure analysis. The structure determination revealed (sp3C)‐H…O–hydrogen bonding in the solid state. Acid‐base reaction by methanolysis affords ionic [Me2NH2] [O2As(OMe)2] while iodide is oxidized to iodine.
Gas phase structure and vibrational spectra of dimethoxysulfane (CH3O)2S
Authors: Baumeister Edgar , Oberhammer Heinz , Schmidt Heinar , Steudel Ralf
Published: January 2005

The vapor phase structure of (CH3O)2S [1] has been investigated by electron diffraction and ab initio MO calculations, which both result in a C2 symmetry for the most stable geometry, the Cs conformer being less stable by about 12 kJ/mol. The torsional barrier for rotation about one SO bond was calculated as 37 kJ/mol (trans barrier). The geometrical parameters (electron diffraction) of the C2 conformer are: dSO = 162.5(2), dCO = 142.6(3), dCH = 110.5(7) pm angles OSO = 103(1)°, SOC = 115.9(4)°, HCH = 109(1)°, torsional angle COSO = 84(3)°. Geometrical data calculated with 6‐31G* basis set agree well with the diffraction data; calculated dipole moments 1.1 D (C2) and 3.3 D (Cs).

The infrared spectrum of gaseous (CH3O)2S and the Raman spectra of liquid and solid (CH3O)2S are reported and have been almost fully assigned to the 27 fundamental vibrations.
Phosphonic systems: 5. Prototropic equilibria of diethyl alkenylphosphonates
Authors: Gerber J. P. , Modro T. A. , Wagener C. C. P. , Zwierzak A.
Published: January 2005

Base‐catalyzed prototropic equilibria for nine pairs of diethyl 1‐ and 2‐alkenylphosphonates have been determined. The results, together with those reported elsewhere for three other pairs, demonstrated that the diethoxyphosphoryl group PO3Et2 has only a very weakly stabilizing effect on the adjacent carbon–carbon double bond. The decisive factors are the number of carbon atoms attached to the double bond and the number of hydrogen atoms available for hyperconjugation.
First 1‐phospha‐1,3‐dienes unsubstituted in the carbon chain by pyrolysis of diallylphosphines: A novel route to the phosphorus—carbon double bond
Authors: Martin Gonzalo , Ocando‐Mavarez Edgar
Published: January 2005

Allylic phosphine systems were studied as phosphorus–carbon double bond precursors. 1‐Phenyl and 1‐butyl‐1‐phospha‐1,3‐dienes were generated by pyrolysis at 350–460°C of the corresponding diallyl phosphines in a stirred‐flow reactor. The unsubstituted phosphadienes generated in this manner dimerized; the formation of [4 + 2] cycloaddition products was confirmed by NMR and mass spectroscopic analysis. 31P NMR data of the 1‐phospha‐1,3‐dienes were obtained.
Theoretical studies on the diazacyclopentadienylidenes: An analysis of aromatic versus nonaromatic systems and singlet versus triplet reactivity
Authors: Pasto Daniel J.
Published: January 2005

Ab initio molecular orbital calculations have been carried out on the various electronic states of 2,3‐ (6), 2,4‐ (7), 2,5‐ (8), and 3,4‐diazacyclopentadienylidene (9) at the fully geometry optimized 6–31G* level, with single point calculations being carried out at the MP2/6–31G* level. The calculated geometries are interpreted in terms of the degree of occupancy and the nature of the π and σ‐nonbonded MO's. At the 6–31G* level the five π‐electron, π,σ‐triplet states were calculated to be considerably lower in energy. At the MP2/6–31G* level, however, with 7 the six π‐electron singlet state is calculated to lie only slightly above the five π‐electron triplet (0.4 kcal mole−1), whereas with 8 and 9 the aromatic six π‐electron singlet states are calculated to be lower in energy (9.0 and 8.1 kcal mole−1). With 3 and 9 the aromatic six π‐electron σ‐triplet states lie only 3.6 and 5.5 kcal mole−1 above the lowest energy states. It is concluded that, in general, the energy gained by having an electron in a lower energy σ‐type MO instead of a higher energy π MO effectively offsets the energy gained by having an aromatic π system. The results are discussed in terms of the observed chemistry of 6–9 and their substituted systems.
1‐acetoxyvinyl phosphonates: Facile synthesis via catalytic acylation of dialkyl phosphites
Authors: Tyryshkin Nikolay I. , Fuzshenokova Alexandra V. , Vedernikov Andrey N. , Solomonov Boris N.
Published: January 2005

A new and facile method of synthesis of 1‐acetoxyvinyl phosphonates (2) has been found. Dialkyl phosphites react readily with acetic anhydride in acetonitrile solution in the presence of catalysts to produce 2 and acylphosphonates (1) as a minor product. The most efficient catalysts are metal compounds of variable valency: iron(II), iron(III), and cobalt(II) chlorides. The same compounds catalyze transformation of 1 into 2 in an acetonitrile solution of acetic anhydride.