bluuebunny/crossref_metadata_2025 huggingface dataset:
Vibration spectrum and normal coordinate analysis of the pyrothiophosphates Na4P2S7, Na2FeP2S7, and Ag4P2S7
Authors: Menzel Frank , Ohse Lothar , Brockner Wolfgang
Published: January 2005

Na4P2S7, Na2FeP2S7, and Ag4P2S7 were prepared by elemental synthesis at high temperatures and were characterized by vibration spectra and differential thermal analysis (DTA). A normal coordinate analysis was performed for P2S4−7. Additional vibration frequencies indicate the presence of the decathiotriphosphate anion P3S5−10. The formation of higher thiophosphates of the type PnS(n+2)‐3n+1 with n ≥ 4 cannot be excluded.
Phosphate–Phosphonate conversion: Nucleophilic displacement reactions involving phosphoric amides and alkyllithiums
Authors: Patois Carl , Savignac Philippe
Published: January 2005

Alkylation at phosphorus with alkyllithiums of acyclic, 5‐membered, and 6‐membered cyclic phosphoric amides was investigated. The chlorinated derivatives reacted in all cases to afford stable α‐(lithioalkyl)phosphonamides. Only 2‐ethoxy‐2‐oxo‐1,3‐dimethyl‐1,3,2‐diazaphospholidine reacted similarly. The study has shown that steric hindrance at phosphorus is the main control of the reaction.
Substituted selenourea–tellurium tetrahalide adducts: Precursors to selenium–tellurium alloys
Authors: Pathirana Hema M. K. K. , Zingaro Ralph A. , Meyers Edward A. , Reibenspies Joseph H. , Dufner D. Carl
Published: January 2005

N,N‐Dimethylselenourea (DMSeU) yields, with TeX4 (X = Cl or Br), a variety of compounds having bonds from selenium to tellurium. Excluding molecules of solvation these compounds display the following stoichiometries: [(DMSeU)4Te]X2, (DMSeU)3(TeX4)2, and (DMSeU)2Te2X6. Tetramethylselenourea (TMSeU) gives, with TeBr4, crystals of (TMSeU)2TeBr4. Both the carbon–selenium and tellurium–halogen bonds undergo hydrolysis under mild conditions to yield precipitates that are alloys of selenium and tellurium. Thus, this group of compounds affords a new approach to the synthesis of selenium–tellurium alloys. Some of the properties of these compounds, as well as the crystal structure of [(DMSeU)4Te]Cl2, are described in this article.
New fluorine derivatives of methylcyclohexasilane
Authors: Hengge Edwin F. , Hassler Karl , Schrank Franz
Published: January 2005

1,1‐Difluorodecamethyl‐ and 1,1,4,4‐tetrafluorooctamethylcyclohexasilane were synthesized by the reaction of LiF with the corresponding trifluoromethanesulfonic derivatives and were characterized by spectroscopic methods, mainly by modern NMR techniques. The stability of the fluorinated cyclosilanes decreases with an increase of fluorine substituents. This seems to be the reason for the instability of perfluorinated cyclosilanes.
Polyhalogenalkoxy(aryloxy)chloro‐ and bromophosphoranes
Authors: Markovsky Leonid N. , Kozlov Ernest S. , Shermolovich Yury G.
Published: January 2005

The data on the synthesis, stereochemistry, and molecular dynamics of alkoxy(aryloxy)halogenphosphoranes of acyclic structure, as well as of halogenphosphoranes containing the pentacoordinate phosphorus atom in the 1,4,2‐dioxophospholane cycle and the node of bicyclo[2.2.2]octane system, are systematized. The influence of spatial properties of polyhalogenalkyl substituents on thermal stability and structure of adducts from tris(polyhalogenalkyl) phosphites with chlorine and bromine is ascertained. The effect of the phosphorus atom inclusion into the cycle and node of the bicyclooctane system on its pentacoordinate state stability is investigated.
Some aminophosphinocarboxylic acids and their derivatives
Authors: Mastryukova T. A.
Published: January 2005

The addition of Schiff bases of α‐aminoacid esters to vinylphosphoryl compounds was studied as a method for the synthesis of phosphinothricin and its analogues. The reaction was found to proceed smoothly in DMSO in the presence of strong nitrogen bases and under the conditions of phase transfer catalysis. The Claisen condensation of β‐phosphorylated propionitrile with diethyl oxalate was studied; phosphorylated derivatives of hydroxycitraconic acid nitrile were prepared on hydrolysis; transformation of such a derivative into a cyclic imide as well as into trimethylsilyl esters of these acids and their Z → E transformation were investigated. Cyclization reactions between α,ω‐dibromoalkanes and phosphoryl compounds containing an active methylene group affording cyclopropane and other cyclic derivatives were studied. The cyclopropane ring is cleaved by amines to give aminophosphinocarboxylic acids.
Application of phosphonate and thiophosphate analogues of nucleotides to studies of some enzyme reactions
Authors: Blackburn G. Michael , Ashton Peter R. , Guo Mao‐Jun , Rogers Michael , Taylor Graham , Guranowski Andrzej , Watts Donald
Published: January 2005

The enzymatic cleavage of a scissile PO bond can be blocked by recourse to phosphonate analogues of biological phosphate esters. α‐Fluorophosphonates have an enhanced electronegativity at the bridging carbon, which, in many cases, makes them superior to simple methylene phosphonates for the study of enzyme reactions. Thus, the β,γ‐difluoro‐methylene analogue of ATP is a good substrate for the interferon‐induced (2→5)An synthetase, which converts it into a (2→5)A4 species having a 5′‐β,γ‐difluoromethylenetriphosphate. This binds strongly to RNase L but does not activate it. The unsymmetrical Ap4Aases from Artemia and Lupin are strongly inhibited by P1,P4‐dithiophosphate analogues of diadenosyl‐5′,5‴‐P1,P4‐tetraphosphate although nonregiospecific cleavage of certain P2,P3‐methylene analogues can be observed. Some of these analogues are remarkably effective inhibitors of platelet aggregation and are effective inhibitors in vivo of arterial blood‐clotting in rabbits. Separation of all diastereoisomers of P1,P4‐dithiophosphate analogues of Ap4A is achieved cleanly using reverse‐phase hplc chromatography and this provides direct access to β,γ‐CHF‐bridged analogues of ATP with resolved stereochemistry at the CHF center. Lastly, growing cells of Dictyostelium discoideum not only tolerate a range of substituted methylene bisphosphonates in their growth medium but actually incorporate them into nucleotide analogues of ATP and Ap4A.
Enzymatic and chemical reactivities of sym‐monothiopyrophosphate
Authors: Halkides Christopher J. , Lightcap Eric S. , Frey Perry A.
Published: January 2005

The synthesis of sym‐monothiopyrophosphate (MTP) is described and the relative hydrolysis rate constants are reported for the dianion, trianion, and tetraanion in aqueous solution. The MTP‐dianion undergoes hydrolysis at a rate 5 x 107‐fold faster than the dianion of pyrophosphate (PPi) and the trianion undergoes hydrolysis 2.7 x 107‐fold faster than PPi‐trianion. The entropy of activation for the hydrolysis of MTP‐trianion is 0.2 cal/deg/mol, and the enthalpy of activation is 19.7 kcal/mol. The hydrolysis appears to involve a dissociative transition state. The hydrolysis of the tetramethyl ester of MTP, in contrast, appears to involve an associative transition state. The Mg complex of MTP is a reasonable substrate for PPi‐dependent phosphofructokinase and inorganic pyrophosphatase, despite its larger size relative to PPi. Therefore, MTP is tolerated within the active sites and in the transition states of enzymes that catalyze phosphoryl transfer from PPi to acceptor molecules. These observations are consistent with the transition states for these enzymes being dissociative in nature, although they do not prove that they are dissociative. MTP is, on the other hand, not a substrate for acetyl‐CoA synthase, an enzyme that utilizes the Mg complex of PPi as a specific acceptor for the adenylyl group, an alkylphosphoryl group. Inasmuch as nonenzymatic reactions of this type involve associative transition states, it may be that the larger size of MTP relative to PPi undermines the catalytic process in the active site of acetyl‐CoA synthase, which may catalyze adenylyl transfer through an associative transition state.
Conformational properties of cyclic pentaalkoxy phosphoranes: Apical–equatorial attachment and nonchair conformation of the phosphorus‐containing six‐membered ring
Authors: Yu Jaehoon , Sopchik Alan E. , Arif Atta M. , Bentrude Wesley G. , Roeschenthaler G.‐V.
Published: January 2005

A series of phosphoranes with pentacovalent phosphorus contained in a 1,3,2‐dioxaphosphorinane ring have been studied by 1H NMR. One compound was investigated by low‐temperature 13C NMR and another by X‐ray crystallography. Although the 1H NMR parameters observed are time‐averaged, the coupling constants can be accounted for if the phosphoranes have the six‐membered ring attached apical–equatorial to phosphorus and occupy in solution rapidly isomerizing boat or slightly twisted boat conformations similar to that found in the X‐ray study.
Conformational transmission in pentacoordinated phosphorus systems, modelling the activated state of cyclic AMP
Authors: Broeders Niek L. H. L. , Koole Leo H. , Buck Henk M.
Published: January 2005

The proposed activated state of cyclic adenosine 3′,5′‐monophosphate (cAMP) is modelled by two nucleoside cyclic 3 ′,5 ′ Pv‐TBP compounds 3 and 4. The reason for the design of compound 3, in which a probe fragment (OCH2CH2OCH3 group) is linked to phosphorus, was reflected in a conformational transmission effect, which occurs when the probe is located in the axis of a Pv‐TBP. This means that the six‐membered 3′5′‐dioxaphosphorinane ring predominantly remains in a diequatorial (e,e) orientation. In the absence of conformational transmission, as in compound 4, the 3′,5′‐dioxaphosphorinane ring favors an equatorial‐axial (e,a) orientation. From this we conclude that the occurrence of conformational transmission can stabilize the (e,e) orientation of the 3′,5′‐ring. This can be of relevance to the activation of protein kinase by cAMP. In order to obtain more structural information from 3 and 4, we performed MNDO calculations on the models 8–10. These calculations revealed that the (e,e) orientation of the 3′,5′‐ring is destabilized by 3–4 kcal/mol compared to the (e,a) orientation. For the (e,a) geometry, the 3′,5′‐ring adopts a twist conformation, whereas the (e,e) orientated 3′,5′‐ring shows a half‐chair geometry.
Molecular modeling of the Wittig olefination reaction: Part 2: A molecular orbital approach at the MNDO‐PM3 level
Authors: Marí Frank , Lahti Paul M. , McEwen William E.
Published: January 2005

We have shown that the MNDO‐PM3 semiempirical molecular orbital method is capable of yielding calculated structures of oxaphosphetanes and ylides that are comparable with the experimentally known structures.

The MNDO‐PM3 method also reproduces the geometric and thermodynamic parameters of the “mythyical Witting half‐reaction”, previously calculated using a more elaborate and costly ab initio molecular orbital approach. In addition, using the SADDLE routine, we were able to find a transition state for this half‐reaction. This transition state resembles geometrically the transition state found using the ab initio approach (4‐31G* level). The energy of activation was calculated to be 9.2 kcal/mole, which is fairly comparable with the ab initio reslt of 5.2 kcal/mole.

According to our calculations, and in general agreement with findings of Volatron and Eisenstein [11], the mythical Witting reaction reaction would be expected to proceed through a planar transition state for the cycloaddition of the ylide and the aldehyde in a process that superficially seems to be a synchronous one. However, an analysis of the evolution of the bond orders and the localized molecular orbitals throughout the reaction indicates that the PO bond has not been formed in the transition state, whereas the CC bond is about 40% formed. Therefore, the mythical Wittig half‐reaction is best described as a very asynchronous cycloaddition (a bordeline two step mechanism) with a planar geometry in the transition state, composed of a multi‐centered mPCCO bond orbital and with the phosphorus and the oxygen atoms sharing a strong attractive charge interaction. A similar description results from computations of the Wittig reactions of H3CHCH3 and (C6H5)3PCHCH3 with H3CCHO, which is inconsistent with the Vedejs geometry.
Reaction of allyl bromide with carbonyl compounds mediated by tributylbismuthine [1]
Authors: Huang Yao‐Zeng , Liao Yi
Published: January 2005

In the presence of tributylbismuthine, allyl bromide was found to react with either aldehydes or ketones to give the corresponding homoallylic alcohols and their allylic ethers in good total yields.
Coupling constants in cis‐phosphine platinum complexes containing chalcogen‐nitride anions
Authors: Kelly Paul F. , Parkin Ivan P. , Sheppard Richard N. , Woollins J. Derek
Published: January 2005

The 31P NMR spectra of complexes of the type Pt(SeSN2)(PR3)2 and Pt(Se2N2(PR3)2) display trans 2J{77Se31P} couplings of ca. 30–80 Hz, with no corresponding cis coupling; in contrast Pt(TeSN2)(PMe2Ph2 has both trans and cis J{125Te31} coupling of 146 Hz and 103 Hz respectively. The 31 spectra of the complexes Pt(S215N2)(PMe2)P2 nd [Pt(S215N2)Cl(PMe2)Ph)]− show both 2J‐ and 4J{15N31P} couplings, which alter substantially upon protonation of the S2N22− ligand. The 15N NMR spectra of Pt(S215N2H)Cl(PMe2Ph) and Pt(S315N)Cl(PMe2Ph) show the presence of both 31P15N and 195Pt15N couplings but no significant 15N15N interactions.
X‐Ray and 31P CP MAS NMR studies of bis(dialkoxythiophosphoryl) disulfides
Authors: Potrzebowski Marek J. , Reinbenspies Joseph H. , Zhong Zhiang
Published: January 2005

The crystal and molecular structures of the title compounds were determined by X‐ray diffraction technique from diffractometer intensity measurements. It has been found that two homologous disulfides, bis(dimethoxythiophosphoryl) disulfide 1 and bis(dineopentoxythiophosphoryl) disulfide 2, form different molecular and crystal structures with space groups C2/c and P&1macr;, respectively. These results were confirmed by 31P CP MAS NMR studies, which showed that under favorable conditions the solid state NMR may lead to determination of the number of crystallographically unique phosphorus atoms. Moreover, the variation of the disulfide S–S bond length versus torsional P–S–S–P angles was observed.
Catalytic trimerization of isocyanates by neutral pentacoordinated silicon hydrides
Authors: Corriu Robert J. P. , Lanneau Gérard F. , Mehta Vimal D.
Published: January 2005

Pentacoordinated hydrosilanes react with excess of aryl isocyanates to give isocyanurates under mild and neutral conditions. The catalytic species are the initially formed N‐silylformamides, which incorporate three equivalents of isocyanate, and then rearrange to N‐silylformamide and isocyanurates.
Facile synthesis of 2,4‐dioxo‐1,2,3,4‐tetrahydroquinazolines by sulfur‐assisted carbonylation with carbon monoxide
Authors: Miyata Toshiyuki , Mizuno Takumi , Nagahama Yoshio , Nishiguchi Ikuzo , Hirashima Tsuneaki , Sonoda Noboru
Published: January 2005

2,4‐Dioxo‐1,2,3,4‐tetrahydroquinazolines were easily synthesized in excellent yields by sulfur‐assisted carbonylation of 2′‐aminobenzamides with carbon monoxide in the presence of a base, such as DBU or DBN.
Does the ipso‐carbon chemical shift tell us anything about the structure of phenylated phosphorus compounds?
Authors: Liu Zi‐Ping , Schlosser Manfred
Published: January 2005

The nuclear magnetic resonance signals exhibited by the ipso‐carbon atoms of a variety of phenylated phosphorus compounds were found to span over the remarkably wide range of + 162 to + 117 ppm. Nevertheless, these changes in chemical shifts have little diagnostic value. They are tentatively attributed to a charge‐mediated contraction and expansion of the C,P σ‐bond orbital on one hand and to a σ‐bond induced deformation of the aromatic π‐electron cloud on the other.
Ligand exchange reactions of aryl pyridyl sulfoxides with grignard reagents: Convenient preparation of 3‐ and 4‐pyridyl grignard reagents and examination of the leaving abilities of pyridyl anions
Authors: Shibutani Tadao , Fujihara Hisashi , Furukawa Naomichi , Oae Shigeru
Published: January 2005

Aryl 3‐ and 4‐pyridyl sulfoxides undergo ligand exchange in reactions with aryl Grignard reagents to generate 3‐ and 4‐pyridyl Grignard reagents, which, upon treatment with aldehydes or ketones, give the corresponding addition products in moderate‐to‐good yields. The mechanism for the exchange reaction was investigated by treating optically active 3‐ and 4‐pyridyl p‐tolyl sulfoxides with a phenyl Grignard reagent. Inversion of the configuration of the sulfur atom was the stereochemical result of the reactions. In the reactions of phenyl 2‐pyridyl sulfoxide with Grignard reagents, the leaving ability of the 2‐pyridyl group competes with that of the phenyl group. Both the experimental and MO calculated enthalpy values for deprotonation of α‐, β‐, and γ‐protons of pyridine in the gas phase [1] are in accordance with the following order of the leaving abilities of aryl and pyridyl Grignard reagents: 4‐PyMgBr > 3‐PyMgBr » PhMgBr > p‐TolMgBr > 2‐PyMgBr.
Organoborane‐mediated synthesis of functional polymers: A review
Authors: Chung T. C. , Schulz D. N.
Published: January 2005

This article reviews recent advances in the synthesis of polar functional polymers via the mediation of organoborane monomers and polymers. Both direct polymerization and post‐polymerization functionalization processes are described. Organoborane‐assisted Ziegler–Natta, metathesis, and hydroboration (haloboration) polymerizations are presented. Moreover, the special problems and opportunities of polymer modification of olefin containing homo and copolymers by organoboranes are discussed.
Study of the reaction of methyltris(dimethylamino)silane with diamines
Authors: Cragg R. Harry , Ma C. Kit
Published: January 2005

Tris(dimethylamino)methylsilane reacts with N,N′‐dialkyldiamines to give the corresponding substituted 1,3,2‐diazasilacycloalkanes. In contrast, the reaction with an N‐alkyldiamine yields the corresponding polycyclic silazane.
The structure of tetramethyl μ‐monothiopyrophosphate
Authors: Halkides Christopher J. , Benning Matthew , Frey Perry A.
Published: January 2005

The compound tetramethyl μ‐monothiopyrophosphate (C4H12O6P2S) crystallizes in the monoclinic space group C 2/c, with (at ‐130°C) a = 10.322 Å, b = 8.229 Å, c = 12.062 Å, β = 98.44°, and Dcalc = 1.639 g/mL3 and Z = 4. The crystal structure has been determined by single crystal X‐ray diffraction to give a final R value of 0.0329 for 614 independent observed reflections [F˚ > 2.5σ(F˚)]. The sulfur atom resides on a crystallographic two‐fold axis. The PSP bond angle is 105.4° and the PS bond lengths are 2.093 Å. The bond angles around phosphorus range from 99.1° to 118.2°. The terminal PO bond is 1.465 Å, and the methoxyl PO bond is about 1.556 Å. The H3COP bond angle is about 119.5°. Many structural features are interpreted in terms of π‐bonding to phosphorus. Comparisons with the structures of pyrophosphate and related compounds indicate that the combined effects of increased acuteness of the PSP bond and the increased length of the P—S bonds lead to an increase of about 0.4 Å in the separation of phosphorus atoms in the sulfur‐bridging compound. These facts, together with the weakness of the PS bond, must be taken into account in the interpretation of kinetic data for enzymatic reactions of phosphorothiolates as substrates in place of phosphates.
Conformational study of 1,4‐thiazinan‐3‐one
Authors: Koskimies Jorma K. , Halonen Aija
Published: January 2005

The proton NMR spectra of several 1,4‐thiazinan‐3‐ones were analyzed using LAOCOON. The geminal and vicinal coupling constants indicate that the ring conformation of this heterocycle is a half‐chair similar to δ‐valerolactam. Molecular mechanics calculations show that the energy of the boat is only slightly higher than that of the half‐chair. The conformational equilibria of methyl‐substituted compounds were calculated by the coupling constant method. These energies are compared to those obtained by molecular mechanics.
Systematic series of azacycl[3.3.3]azines of varying nitrogen content: Nitrogen‐15 magnetic resonance spectra
Authors: Kanamori Keiko , Roberts John D. , Rossman Mitchell A. , Leonard Nelson J.
Published: January 2005

Nitrogen‐15 NMR spectra were obtained for a systematic series of azacycl[3.3.3]azines: 1,3,4,6,7,9‐hexaaza‐,1,3,4,6,7‐pentaaza‐,1,3,4,6‐tetraaza‐, 1,3,4,6,8‐pentaaza‐, and 1,3,6‐triazacycl[3.3.3]azine. The magnetic resonance data were compared with other physical and spectroscopic properties available for the series relative to the diminishing number of peripheral nitrogens in alternating positions. The properties of 1,3,4,6,8‐pentaazacycl[3.3.3]azine, which has a peripheral 1,4‐diazine‐type nitrogen, are distinct from those of the rest of the series.
Stereocontrolled enantioselective addition of diethylzinc to aldehydes using new chiral aminoalcohols
Authors: Kim Yong Hae , Park Doo Han , Byun Il Suk
Published: January 2005

The new chiral β‐aminoalcohols of indolinylmethanols (1) and their reduced derivatives (2) were synthesized from (S)‐indoline‐2‐carboxylic acid. Both (R) and (S) enantiomers of the optically active secondary alcohols have been successfully obtained in high enantiomeric excess from the stereoselective addition of diethylzinc to the aldehydes catalyzed by the chiral aminoalcohols (1 and 2). The sense of the asymmetric induction and the degrees of enantioselectivities turned out to be highly dependent on the structure of the catalysts: The presence of the catalyst 1 afforded the (S)‐configuration of the corresponding alcohols; on the other hand, the presence of 2 afforded the (R)‐configuration of the alcohols in high enantiomeric selectivity.
Preparation and reactions of 3‐oxa‐ and 4‐oxa‐5‐hexenyllithiums
Authors: Bailey William F. , Punzalan Eric R. , Zarcone Lyn M. J.
Published: January 2005

Low‐temperature lithium–iodine exchange between tert‐butyllithium and the appropriate iodide has been used to generate 3‐oxa‐5‐hexenyllithium and a variety of 4‐oxa‐5‐hexenyllithiums. The 3‐oxa system is inherently unstable and fragments via facile β‐elimination to give the anion of allyl alcohol and ethylene. The 4‐oxa‐5‐hexenyllithiums, in contrast, are stable at low temperatures but undergo novel isomerization upon warming to deliver the lithium salt of a 4‐alken‐1‐ol in the formal equivalent of an unprecedented [1,4]‐Wittig rearrangement. The rearrangement is most likely mediated by 5‐exo‐trig ring closure of the 4‐oxa‐5‐hexenyllithium to a (2‐tetrahydrofuranyl)methyllithium followed by rapid opening to the alkoxide.
Heats of formation of organic molecules by ab initio methods: Thiaalkanes
Authors: Allinger Norman L. , Yang Linrong , Motoc Ioan , Bender Charles , Labanowski Jan K.
Published: January 2005

The bond energy scheme for calculating heats of formation of organic molecules from ab initio data (6–31G*) has been extended to include 24 compounds containing sulfur in the sulfide oxidation state. The rms deviation from the experimental values for these compounds is 0.54 kcal/mol, which is approximately experimental error.
Retention stereochemistry in ligand coupling reaction of optically active (1 R)‐phenylethyl 2‐quinolyl (R)‐ and (S)‐sulfoxide with methylmagnesium bromide
Authors: Uenishi Jun'ichi , Yamamoto Atsumi , Takeda Takashi , Wakabayashi Shoji , Oae Shigeru
Published: January 2005

Reactions of (+)‐(1R)‐phenylethyl 2‐quinolyl (R)‐ sulfoxide 7a and (−)‐(1R)‐phenylethyl 2‐quinolyl (S)‐ sulfoxide 7b with methylmagnesium bromide were examined. The reaction gave (R)‐2‐(1‐phenylethyl)quinoline 9 as a ligand‐coupling product, and a mixture of methyl(1R)‐phenylethyl(R)‐and (S)‐sulfoxide 11a and 11b as ligand exchange products. The other (S) stereoisomer at the 1‐phenylethyl carbon center was not detected in the reaction products. That is, both the ligand coupling and ligand exchange reactions proceeded with retention of configuration at the asymmetric carbon center.
Organophosphorus chemistry 23 [1], the reaction of α,β‐unsaturated nitriles with alkyl phosphites and phosphorus ylides
Authors: Mahran Mohamed R. , Abdou Wafaa M. , AbdEl‐Rahman Naglaa M. , Khidre Maha D.
Published: January 2005

Wittig reagents 2 react with furfurylidenemalonitrile (1a) and thienylidenemalonitrile (1b) to give a mixture of products (6 and 7). Compound 1b reacts with di‐alkyl phosphites (3) and trialkyl phosphites (4) to give the phosphonate 1:1 adducts 9 and 12, respectively. Structures of the new products were confirmed on the basis of elemental analyses and spectral studies.
Synthesis of fluorinated 2‐oxo‐1,4,2‐oxazaphosphol‐4‐ines and their opening by alcohols
Authors: Korenchenko Olga V. , Aksinenko Aleksey Yu. , Sokolov Vladimir B. , Martynov Ivan V.
Published: January 2005

Trifluoromethyl‐substituted 1,4,2λ5‐oxazaphosphol‐4‐ines from phosphorus dichlorides and N‐acylimines of hexafluoroacetone have been synthesized and characterized by 1H, 19F, and 31P NMR. Alcohols open these oxazaphospholines at the P–O bond, forming the corresponding esters.
5‐Methyl‐2‐phenyl‐2H‐1,2,3‐diazaarsole in reaction with ethyl diazoacetate
Authors: Arbuzov Boris A. , Zabotina Elena Ya. , Dianova Evelina N. , Litvinov Igor A. , Naumov Victor A. , Latypov Shamil K. , Il'asov Ahat V.
Published: January 2005

5‐Methyl‐2‐phenyl‐2H‐ 1,2,3‐diazaarsole 1 reacts with ethyl diazoacetate to form a 1:1 bicyclic product 3a, 8‐ethoxycarbonyl‐4‐methyl‐2‐phenyl‐1‐arsa‐2,3,6,7‐tetraazabicyclo[3.3.0]octa‐3.7‐diene. The latter isomerizes to a two‐coordinate arsenic compound 5, 3‐ethoxycarbonyl‐5‐[α‐(phenylhydrazono)ethyl] 1‐1,2,4‐diazaarsole. The X‐ray crystal structure analyses of both products 3a and 5 have been carried out.
(2,4,6‐Tri‐tert‐butylphenylimino)thioxo‐and ‐selenoxophosphoranes. Synthesis and structural characterization
Authors: Romanenko Vadim D. , Ruban Alexander V. , Drapailo Andrei B. , Chernega Alexander N. , Rusanov Eduard B.
Published: January 2005

A series of stable imino(chalcogeno)phosphoranes R  P( X)  NAr, RPh, 2, 4, 6‐Me3C6H2, 2, 4, 6‐i‐Pr3C6H2; Ar 2, 4, 6‐t‐Bu3C6H2; X  S, Se (5bd, 6b,c), has been prepared by the oxidation of λ3‐imino‐phosphines R  P  N  Ar (4b‐d) with sulfur and selenium. When P  (tert‐butyl)iminophosphine, t‐Bu  P  N‐  Ar (4a), was reacted with S8 and Seiv the corresponding oligomeric metaphosphonimidates 7, 8 were obtained. All new compounds are characterized by their NMR spectra. The constitution of the imino(thioxo)phosphorane 5d is proved by X‐ray crystal structure determination.
Syntheses of stereodefined β‐alkylidene‐γ‐lactones and substituted β, γ‐unsaturated δ‐lactones
Authors: Lee Yuhshan , Leong William , Zweifel George
Published: January 2005

1‐Trimethylsilyl‐1,3‐diyne derived trans‐bis(trimethylstannyl) enynes undergo stepwise transmetallation with methyllithium to furnish the corresponding enynyllithium reagents. The application, in various orders, of a sequence of transmetallation‐protonation‐alkylation‐hydroxyalkylation‐hydroboration‐oxidation reactions provides a novel approach to stereo‐defined β‐alkylidene γ‐lactones and β, γ‐unsaturated δ‐lactones.
Cyclization reactions of ω‐tosyloxy‐1‐alkynyl‐ and ω‐tosyloxy‐1‐alkenylborates and their ω‐halo analogues
Authors: Negishi Ei‐ichi , Nguyen Thinh , Boardman Larry D. , Sawada Hiroyuki , Morrison James A.
Published: January 2005

The reaction of trialkylboranes with ω‐tosyloxy‐1‐lithio‐1‐alkynes can induce transfer of an alkyl group from the boron atom to the alkynyl carbon atom with concomitant formation of four‐ through six‐membered carbocycles via intramolecular displacement of the ω‐tosyloxy group. The stereoselectivity of the reaction, however, is low (anti/syn≃1.6–1.7). The corresponding reaction of ω‐halo‐ or ω‐tosyloxy‐1‐alkenylborates also gives exocyclic alkenes via 1,2‐migration‐cyclization followed by dehydroboration. In the cases of cyclopropanation, cyclopropylcarbinyl‐to‐homopropargyl rearrangement rather than dehydroboration takes place. Diphenylzirconocene reacts similarly with 6‐lithio‐5‐hexynyl tosylate to give phenylmethylenecyclopentane in 45% yield. On the other hand, attempts to induce a similar migration with phenyl derivatives of Y, V, Cr, and Mn have led to < 5–10% yields of the same cyclization product.
X‐Ray determination of the effective charges on sulfur and phosphorus atoms in chemical compounds
Authors: Dolenko G. N. , Litvin A. L. , Elin V. P.
Published: January 2005

The dependencies of Kα line shifts of the P and S atoms on effective charges of the atoms, calculated by CNDO/S, CNDO/2, INDO, and MNDO methods in the minimal and extended basis sets, have been investigated for model compounds. Good linear relationships between Kα shifts and atomic charges have been obtained for all cases investigated except for CNDO/2 and INDO calculations in the extended basis set. It is found that the PS bond ionicity is a nearly constant value, whereas the PS bond ionicity increases linearly with an increase in the positive charge of the central P atom. It is shown that the P and S atom charge in sulfides and phosphines containing no substituents with a strong M‐effect at the central atom depend only on inductive substituent effects. Also, the positive charge on the central atom increases with the growth of the π‐donor properties of substituents in sulfides and phosphines containing substituents exerting a strong M‐effect, as well as in phosphoryl and thiophosphoryl compounds and sulfones.
Substitution of 2‐phosphaindolizines by bromine and by chlorophosphines
Authors: Bansal Raj K. , Gupta Neelima , Kabra Vijaya , Spindler Claudia , Karaghiosoff Konstantin , Schmidpeter Alfred
Published: January 2005

Bromine does not add to phosphorus in a 2‐phosphaindolizine 1 but substitutes its 1‐position. The 1‐bromo derivatives 2 are best prepared with Br2/NEt3 or N‐bromosuccinimide. Their hydrolysis is remarkable; it involves a debromination of C‐1, an oxidation of P and a selective opening of the P/C‐3 bond.

PCl3 also causes a substitution of the 1‐position. The resulting 1‐dichlorophosphino derivatives 5 easily undergo a substituent exchange at the exocyclic phosphorus. More 1‐phosphino derivatives are formed in the reaction of 1 with phenyl and diazaphospholyl dichlorophosphine.
Preparation of polyfluorodihydrobenzothiophenes and investigation of some of their chemical properties
Authors: Maksimov Alexander M. , Platonov Vyacheslav E.
Published: January 2005

Co‐pyrolysis of thiophenol or diphenyl disulfide with tetrafluoroethylene or chlorotrifluoroethylene in the presence of oxidants gave 2,2,3,3‐tetrafluoro‐2,3‐dihydrobenzo[b]thiophene (I) or the corresponding chlorotrifluorodihydrobenzothiophenes.

Reactions of compounds synthesized by use of electrophilic and nucleophilic reagents and with oxidants have been studied.
NMR studies on the ligand exchange reactions between diaryl tellurides and phenyllithium: Detection of hypervalent triaryl tellurium ate complexes
Authors: Ogawa Satoshi , Masutomi Yutaka , Furukawa Naomichi , Erata Tomoki
Published: January 2005

Diaryl tellurides undergo rapid ligand exchange and disproportionation reactions on treatment with phenyllithium at −78°C. Triarylteliuranes [10‐Te‐3(C3)]− Li+ were identified as discrete intermediates during the reactions by 125Te, 1H, 13C, and CH‐COSY NMR studies.
Coupling reactions of 2‐aryl‐1,3‐dithiolane‐S‐oxides with MeMgl
Authors: Cheng Wen‐Lung , Luh Tien‐Yau
Published: January 2005

Reactions of 2‐aryl‐1,3‐dithiolane‐S‐oxides 1 with MeMgl in refluxing benzene‐ether furnish a useful procedure for introducing the isopropenyl group. The reaction may proceed via a fragmentation‐coupling process leading to the alkylative olefination product.
Reductive ring opening of cyclopropyl ketones with samarium (II) diiodide
Authors: Kim Yong Hae , Lee In Sang
Published: January 2005

Functionalized cyclopropyl ketones have been found to undergo facile reductive cyclopropane ring opening with samarium (II) diiodide in the presence of a proton source. These reactions were exceedingly rapid, taking place in most cases at −78°C under neutral conditions. An ester group substituted at the C2 position of the cyclopropane ring played an important role in the ring opening of cyclopropyl ketones.
Synthesis of flavins bearing a sulfur functional group and their catalytic activities for reduction of disulfides
Authors: Nagata Toshiyuki , Fujimori Ken , Oae Shigeru
Published: January 2005

Bis‐flavins, each of which bears a disulfide linkage in the molecule, have been synthesized as model compounds for dihydronicotinamide dependent disulfide reductase. These flavins were found to be much better catalysts to promote the reduction of dibenzyl disulfide to α‐toluenethiol than 3‐methyllumiflavin.
Cyclization of N‐propargylaminophosphines—New method for synthesis of 2,5‐dihydro‐1,2‐azaphospholes
Authors: Angelov Christo M. , Enchev Dobromir D.
Published: January 2005

The reaction of N‐methyl‐N‐propargylamine with dialkoxy‐chlorophosphines 1a–e gave N‐dialkoxyphosphinyl‐N‐propargylammonium salts 2a–e which, by heating, undergo cyclization to new five‐membered azaphosphole derivatives 4a–e.
2,6‐Dithiodecahydro‐1H,5H‐Diimidazo[4,5,‐b:4′,5′‐e]Pyrazine and related dioxo‐ and diimino‐decahydrodiimidazopyrazines
Authors: Vedachalam Murugappa , Boyer Joseph H.
Published: January 2005

Thiourea condensed with 1,4‐diformyl‐2,3,5,6‐tetrahydroxypiperazine 2 in the presence of hydrochloric acid to give 2,6‐dithiodecahydro‐1 H,5H‐diimidazo[4,5,‐b:4′,5′‐e]pyrazine 5 isolated as the dihydrochloride salt. The salt 5. 2HCl was converted to the free base 5 by lithium hydroxide, to the dinitrate salt 5. 2HNO3 by silver nitrate, degraded to 2‐thio‐2,3,4,7‐tetrahydro‐1 H‐imidazo[4,5‐b]pyrazine 6 in a reaction with tert‐butyl amine, and converted to 4,8‐dihydro‐4,8‐dinitro‐1H,5H‐diimidazo[4,5‐b:4′,5′‐e]pyrazine‐2,6‐ disulfonic acid 9 by nitric acid (100%) at −40°C. Denitration of the dinitramine 9 to give 4,8‐dihydro‐1H,5H‐diimidazo[4,5‐b:4′,5′‐e]pyrazine 11 was brought about by methanolic hydrogen chloride in ether. In one run nitration without oxidation converted the salt 5 · 2HCl to the dinitrate salt of the 4,8‐dinitro derivative 10; treatment with triethyl amine liberated the free base 10 from the salt. Degradation of 2,6‐dioxo‐1,3,4,5,7,8‐hexanitrodecahydro‐1H,5H‐diimidazo[4,5‐b:4′,5′‐e]pyrazine 12 to 2‐oxo‐2,3‐dihydro‐1,3‐dinitro‐1H‐imidazo[4,5‐b] pyrazine 13 was brought about by hydrochloric acid. Treatment with lithium hydroxide also liberated 2,6‐dioxodecahydro‐1H,5H‐diimidazo [4,5‐b:4′,5′‐e]pyrazine 3 from its dihydrochloride salt. Attempts to liberate 2,6‐diiminodecahydro‐1H, 5H‐diimidazo[4,5‐b:4′,5′‐e]pyrazine 4 from its tetrahydrochloride salt led instead to intractable mixtures. The tetrahydrochloride salt 4 · 4HCl was converted to the dihydrochloride salt 4 · 2HCl in a reaction with tert‐butyl amine.
Polymerization of vinyl derivatives of the main group elements
Authors: McNally Lydia , Allen Christopher W.
Published: January 2005

A survey of selected novel hybrid organic‐inorganic polymers obtained by polymerization and copolymerzation of main group compounds containing vinyl groups is presented. Examples from groups 13 through 16 are discussed with an emphasis on synthesis and quantitative reactivity studies.
P‐Substituted 3‐phosphabicyclo [3.1.0] hexane 3‐oxides from diastereoselective substitution at phosphorus
Authors: Keglevich György , Kovács Attila , Tőke László , Újszászy Kálmán , Argay Gyula , Czugler Mátyás , Kálmán Alajos
Published: January 2005

Preparation of P‐amino‐3‐phosphabicyclo[3.1.0]‐hexane 3‐oxides either by addition of dichlorocarbene to the double bond of 1‐amino‐2,5‐dihydro‐1H‐phosphole 1‐oxides or by substitution of the P‐chloro derivative of the bicyclic system was accomplished. Two different diastereomers are obtained by the two approaches; their 13C NMR spectra were interpreted on the basis of the P‐ethoxy isomers, whose structures were confirmed by X‐ray analysis. The P‐hydroxy adduct was also prepared, and it was found that intermolecular OH … O hydrogen bonding connects the molecules together in the solid phase. This effect eliminates the possibility of diastereoisomerism, as was also observed in the case of P‐hydroxy tetrahydrophosphinine oxides. Thermolysis of the P‐hydroxy adduct is a better way to synthesize 1‐hydroxy‐1,2‐dihydrophosphinine oxides than by hydrolysis of the phosphinic chlorides.
Synthesis, characterization, and X‐ray crystallographic structure of 1,3‐dimethyl‐2(3H)‐imidazoleselone
Authors: Williams Daniel J. , Fawcett‐Brown Melissa R. , Raye Rhonda R. , VanDerveer Donald , Pang Yong T. , Jones Robert L. , Bergbauer Katrina L.
Published: January 2005

The reaction of elemental Se with 1,3‐dimethylimidazolium iodide in methanolic K2CO3 yields 1,3‐dimethyl‐2(3H)‐imidazoleselone for which three addition products, two with bromine and one with iodomethane, have been synthesized and for which X‐ray crystallographic analysis shows the structure to consist of a selenium‐substituted planar heterocyclic ring with bond distances and angles significantly different from those noted for the previously reported sulfur analog [1,3‐dimethyl‐2(3H)‐imidazolethione, dmit]. Crystal data: C5H8N2Se, space group C mcm, M = 175.03, a = 8.625(3), b = 11.447(6), c = 6.900(4) Å, V = 681.24 Å3, Z = 4, Dc = 1.707 g cm−3, D0 = 1.68 g cm−3, λ = 0.71073 Å (Mo‐Kα), μ = 5.35 mm−1, R = 0.034, and Rw = 0.031.
Kinetic studies of hydrolysis of some alkyl benzenesulfinates
Authors: Okuyama Tadashi
Published: January 2005

Hydrolysis reactions of methyl, ethyl, isopropyl, and t‐butyl benzenesulfinates were kinetically investigated. Rates of alkaline hydrolysis decrease with increasing steric effects (Me > Et > i‐Pr > t‐Bu), while the t‐butyl ester is the most reactive in perchloric acid (t‐Bu > Me > Et > i‐Pr). The hydrolysis is faster in HCl and HBr than in HClO4, and the relative rates in the halide acids are not unusual (Me > Et > i‐Pr ∼ t‐Bu). The high reactivity of the t‐butyl ester in HClO4, is ascribed to the reaction at the carbon via the A1 mechanism, while halide ions accelerate the hydrolysis by nucleophilic participation at sulfur.
Stereoselective sulfur extrusion reaction of syn‐ and anti‐10,20‐dibromo‐2,3,12,13‐tetrathia[4.4]metacyclophanes to the corresponding syn‐ and anti‐dithia[3.3]metacyclophanes
Authors: Fujihara Hisashi , Chiu Jer‐Jye , Furukawa Naomichi
Published: January 2005

A new cyclophane, 10,20‐dibromo‐2,3,12,13‐tetrathia[4.4]metacyclophane (1), has been synthesized by the oxidative coupling reaction of 2,6‐bis(mercaptomethyl)‐1‐bromobenzene with I2. Both syn and anti isomers of 1 can be isolated at room temperature. The thermal sulfur extrusion reaction of anti‐1 with (Et2N)3P afforded anti‐9,18‐dibromo‐2,11‐dithia[3.3]metacyclophane, while syn‐1 gave 9,19‐dibromo‐2,11,12‐trithia[3.4]metacyclophane. syn‐9,18‐Dibromo‐2,11‐dithia[3.3]metacyclophane was produced from the photochemical sulfur extrusion of syn‐1 with (MeO)3P.
Formation of allyl‐substituted allene episulfide S‐oxides and their thermal and acid‐catalyzed rearrangements
Authors: Choi Nami , Tokitoh Norihiro , Ando Wataru
Published: January 2005

Oxidation of allyl‐substituted allene episulfides with a peracid gave the corresponding allene episulfide S‐oxides which were found to undergo ready isomerization to bicyclo[2.1.1]thiahexane S‐oxide derivatives on thermolysis or under acid‐catalyzed reaction conditions.
Chlorodiazaphospholines as intermediates in the synthesis of 1,2‐dihydro‐2‐alkenyl‐3H‐pyrazol‐3‐ones and 2‐pyrrolylacetates
Authors: Baccolini Graziano , Biondi Daniele
Published: January 2005

New derivatives of 1,2‐dihydro‐2‐alkenyl‐3H‐pyrazol‐3‐ones 6 and 7 have been synthesized at room temperature by a one‐pot two‐step reaction of PCl3, a ketone methylhydrazone, and a β‐keto ester. With ketone methylhydrazones bearing at least a phenyl group in the α‐positions to the CN bond and in the second step β‐keto esters, such as propionyl‐ or butyrylacetates, we obtained 2‐pyrrolylacetates 8 as unexpected products together with pyrazolones 7. The ratio of the two products depends on the nature of the groups in the α‐positon to the CN bond. A chlorodiazaphospholine 1 is the key intermediate of this new reaction, and a plausible mechanism of formation of the azaheterocycles is reported.
Phosphonic systems. Part 12. Fragmentation‐rearrangement of dialkyl 2‐acyloxyalkylphosphonates
Authors: de Jongh Connie P. , Modro Tomasz A. , Modro Agnes M.
Published: January 2005

Dialkyl esters of 2‐acyloxyalkylphosphonic acids, RCH(OAc)CH2PO3R′2, undergo thermolytic fragmentation to an alkene RCHCH2, a new ester AcOR′, and an alkyl metaphosphate R′OPO2. The reaction represents a new type of a process in which a metaphosphate species is generated from a neutral precursor and involves alkyl group (R′) migration as a prerequisite for the reaction. Mechanistic studies indicate that the reaction involves interaction between the phosphoryl group and the electrophilic center of the Ac group, followed by the intramolecular dealkylation of the POR′ function and the subsequent fragmentation of the intermediate.
Syntheses of β‐amidovinyltellurides and oxazoles by addition reactions of alkynes with benzenetellurinyl trifluoromethanesulfonate in acetonitrile
Authors: Fukumoto Takahiro , Aso Yoshio , Otsubo Tetsuo , Ogura Fumio
Published: January 2005

Benzenetellurinyl trifluoromethanesulfonate in conjunction with acetonitrile readily effected amidotellurinylation reactions with alkynes. Most of the addition reactions proceeded in a trans fashion to form the (E)‐β‐acetamidovinyl phenyl telluroxides. Subsequently, it was found that the prevailing Markovnikov adducts from terminal alkynes immediately isomerized to (Z)‐isomers which were isolated as the corresponding vinyltellurides. On the other hand, the adducts derived from internal alkynes thermally underwent a spontaneous intramolecular cyclization to be transformed eventually into oxazoles.
Studies on organophosphorus compounds 81. A novel synthetic approach to substituted cyclopentane‐1,1‐diylbisphosphonates via Pd(0) catalyzed enyne cyclization
Authors: Li Chaozhong , Yuan Chengye
Published: January 2005

Intramolecular enyne cycloisomerization reactions catalyzed by Pd(PPh3)4 gave 4‐substituted 3‐methylenecyclopentane‐1,1‐diylbisphosphonates in good yield.
Stereoselective synthesis of and atropisomerism in 4‐pyridyl‐3‐(1‐pyridinio)‐3,4‐trans‐1,2,3,4‐tetrahydropyridines and their transformation products
Authors: Shestopalov Anatolij M. , Bogomolova Olga P. , Rodinovskaja Ludmila A. , Litvinov Victor P. , Bujnicki Bogdan , Mikol̀ajczyk Marian , Nesterov Vladimir N. , Struchkov Yurij T.
Published: January 2005

A series of 2‐oxo‐4‐pyridyl‐3‐(1‐pyridinio)‐5‐cyano‐3,4‐trans‐1,2,3,4‐tetrahydropyridine‐6‐6‐olates were prepared by condensation of pyridinium ylides with α,β‐unsaturated carbonyl compounds or more conveniently by a three‐component condensation of pyridinium ylides, pyridine aldehydes, and ethyl cyanoacetate 3 and/or 6. This analogues of the above tetrahydropyridines were prepared in a similar way starting from suitable substrates. Spectroscopic data revealed that the reaction leads to trans‐isomers around the C3‐C4 bond and is atroposelective. The conformation of and tautomerism in the tetrahydropyridines are discussed in the light of 1H NMR data. The reaction of 5‐cyano‐3‐(3‐methyl‐1‐pyridinio)‐2‐oxo‐4‐(3‐pyridyl)‐1,2,3,4‐tetrahydropyridine‐6‐thiolate 10c with phenacyl bromide was found to give 3‐hydroxy‐5‐oxo‐7‐(3‐pyridyl)‐6‐(3‐methyl‐1‐pyridinio)‐3‐phenyl‐8‐cyano‐6,7‐trans‐2,3,6,7‐tetrahydrothiazol[3,2a]pyridine bromide, the crystal and molecular structure of which has been determined by X‐ray crystallographic analysis.
1‐Aminothiaalkanephosphonic acids and their sulfinyl and sulfonyl derivatives: Synthesis and acidic properties
Authors: Kudzin Zbigniew H. , Andrijewski Grzegorz , Drabowicz Józef
Published: January 2005

Several 1‐aminothialkanephosphonic acids 2 were synthesized and selectively oxidized to their sulfinyl 3 and sulfonyl 4 derivatives. For the compounds 2, 3, and 4, their dissociation properties were determined potentiometrically.
A mild and efficient synthesis of intermediates for the Pomeranz‐Fritsch reaction
Authors: Katritzky Alan R. , Yang Zhijun , Cundy Darren J.
Published: January 2005

Reaction of 1‐chloro‐2,2‐dimethoxyethane with sodium azide affords 1‐azido‐2,2‐dimethoxyethane which, upon treatment with triphenylphosphine followed by aromatic aldehydes, alkyl bromides, or isocyanates, gives the corresponding dimethyl α‐arylimino‐, α‐alkylamino‐, and α‐carbodiimido‐acetals, respectively, in good to excellent yields.
Crystal and molecular structure and determination of absolute configuration of two enantimers of methoxycarbonylmethyl carboxymethyl sulfoxide
Authors: Wieczorek Michał W. , Błaszczyk Jarosław , Mikołajczyk Marian , Kiełbasiń;ski Piotr , ŻurawińSki Remigiusz
Published: January 2005

Crystal and molecular structures of two enantiomers of methoxycarbonylmethyl carboxymethyl sulfoxide 2 ( 2(−) and 2(+) ) have been determined by X‐ray methods. Crystals of 2 are orthorhombic, space group P212121, Z = 4, with a = 5.1900(4) Å, b = 8.7960(7) Å, and c = 18.489(2) Å in 2(−) and a = 5.1897(7) Å, b = 8.787(1) Å, and c = 18.520(2) Å in 2(+). Structures 2(−) and 2(+) were refined to R factors equal to 0.041 and 0.052, respectively. The absolute configuration at the sulfur atom in enantiomer 2(−) with [α] = −20° (MeOH) is Rs. (In 2(+), where [α] equals + 20° (MeOH), the absolute configuration at S atom is Ss.) In compounds 2(−) and 2(+), a strong intermolecular hydrogen bond O3H3 … O1 occurs.
Cyclization of Ph2Si(NHNHMe)2. I. Reaction with n‐BuLi/Ph2SiCl2 and ring rearrangement
Authors: He Jiliang , Harrod John F.
Published: January 2005

Reaction of Ph2Si(NHNHMe)2 (1) with n‐BuLi and Ph2SiCl2 in 1 : 2 : 1 ratio afforded 54% of 1,2,4‐triaza‐1‐methyl‐4‐methylamino‐3,3, 5, 5‐tetraphenyl‐3,5‐disilacylopentane (2). In the presence of a catalytic amount of n‐BuLi, 2 is rearranged to two isomers, 1,2,4,5‐tetraaza‐1,4‐dimethyl‐3,3,6,6‐tetraphenyl‐3,6‐disilacyclohexane (3) and 1,2,4,5‐tetraaza‐1,5‐dimethyl‐3,3,6,6‐tetraphenyl‐3,6‐disilacyclohexane (4), with 3 as the major product. The crystal structure of 3 reveals a twist‐boat conformation of the Si2N4 ring [a = 10.691(4) Å, b = 13.178(4) Å, c = 17.812(3) Å, β = 95.11(7)°; monoclinic, P21/n; Z = 4], in which eachN(Me)N(H)unit contains one pyramidal (NH) and one planar (NMe) nitrogen.
The intramolecular sila‐Pummerer cyclization: A new route to sulfur heterocycles
Authors: Still Ian W. J. , Toste F. Dean
Published: January 2005

The generality of the intramolecular cyclization of suitable nucleophilic sites to a S+CH2 center created by a sila‐Pummerer rearrangement has been investigated. Successful nucleophilic sites included the OH group (in alcohols, carboxylic acids, and hydroxylamines) and the NH group (in amines and carbamates): attempts to produce carbon‐based nucleophilic sites were not effective. Successful cyclizations were achieved to produce sulfur heterocycles with 5‐, 6‐, and 7‐membered rings.
Reactions of N‐sulfonyldiarylchalcogenimides with diaryl ditellurides
Authors: Naddaka Vladimir I. , Cherkinskaya Marina L. , Avanesyan Knarik V.
Published: January 2005

Unlike the N‐sulfonylsulfimide 1a, which does not react with diaryl ditellurides 2 even at 180°C, the selenimide 1b, and tellurimides 1c,d convert quantitatively compounds 2 to N,N‐bis‐(N′‐p‐tosylimidoarenetellurinyl)‐p‐tosylamides 4a,b in refluxing benzene. The reactivity of N‐sulfonylchalcogenimides 1 increases in the order S < Se < Te. Diaryl telluroxides 6 readily oxidize ditellurides 2 to arenetellurinic anhydrides 5. The mechanisms of these reactions are discussed.