Model reactions of functionalization of polycarbonate. Reactions of phenyl chloroformate with nucleophiles and cationic polymerization behavior of bicyclo orthoesters containing carbonate group

Some model experiments for functionalization of a polycarbonate were carried out. At first, reactivity of phenyl chloroformate with a few nucleophiles was examined. Reaction with alkyl amines gave corresponding carbamates, but in the case of aniline, formation of a byproduct diarylurea was observed. Reactions with alcohols and phenols afforded carbonates in moderate yields, in which p-nitrophenol and isopropyl alcohol were less reactive. On the basis of these results, 1-ethyl-4-phenoxycarboxymethyl-2,6,7-trioxabicyclo[2.2.2]octane (2) and 1-ethyl-4-ethoxycarboxymethyl-2,6,7-trioxabicyclo[2.2.2]octane (3) were prepared by the reaction of phenyl and ethyl chloroformates with 1-ethyl-4-hydroxymethyl-2,6,7-trioxabicyclo[2.2.2]octane in the presence of tert-amine. 2 polymerized cationically with BF₃OEt₂ at more than 80°C to give a polyether containing both ester and carbonate groups in the side chain, with contamination of a gelled polymer.     

Synthesis of monomers that expand on polymerization. Synthesis and polymerization of 2,6,7-trioxabicyclo[2.2.2]octanes with phenyl groups

2,6,7-Trioxabicyclo[2.2.2]octanes with phenyl group were prepared to obtain monomers which expand on polymerization. 1-Phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane (I) could expand 0.2% during polymerization at a temperature slightly higher than the melting point. 1,4-Diphenyl-2,6,7-trioxabicyclo[2.2.2]octane (II) also expanded as much as 1.4% on polymerization. Further, the hydrolysis of 2,6,7-trioxabicyclo[2.2.2]octanes with p-substituted phenyl groups were investigated to estimate the stability in water.     

Equilibrium polymerization behavior in the cationic single ring‐opening polymerization of bicyclo orthoesters

The synthesis and cationic polymerization of the following bicyclo orthoesters were examined: 4‐ethyl‐2,6,7‐trioxabicyclo[2.2.2]octane, 1,4‐diethyl‐2,6,7‐trioxabicyclo[2.2.2]octane, 4‐ethyl‐1‐phenyl‐2,6,7‐trioxabicyclo[2.2.2]octane, 4‐ethyl‐1‐(4‐methoxyphenyl)‐2,6,7‐trioxabicyclo[2.2.2]octane, and 4‐ethyl‐1‐(4‐nitrophenyl)‐2,6,7‐ trioxabicyclo[2.2.2]octane. All the monomers underwent equilibrium polymerization, which was confirmed by the relationships between the polymerization temperature and monomer conversion. The obtained polymers afforded the original monomers via an acid‐catalyst treatment with a low reagent concentration in CH₂Cl₂ at 20 °C. The equilibrium monomer concentration was constant, regardless of the initial reagent concentration, in both polymerization and depolymerization. The bicyclo orthoesters with a bulky and electron‐withdrawing substituent showed a larger equilibrium monomer concentration. © 2001 John Wiley & Sons, Inc. J Polym Sci Part A: Polym Chem 39: 3159–3167, 2001     

The synthesis,characterization, and polymerization of 1-ethyl-4-[(2-methacryloxy)ethyl carbamoyloxymethyl]-2,6,7-trioxabicyclo[2.2.2]octane

The synthesis of a monomer bearing polymerizable acrylic and bicyclic ortho ester groups is described. The monomer 1-ethyl-4-[(2-methacryloxy)ethyl carbamoyloxymethyl]-2,6,7-trioxabicyclo[2.2.2]octane is characterized by elemental analysis, ¹H- and ¹³C-NMR spectra, mass spectra, and heat of polymerization. The free-radical and ionic polymerization of 4 is probed as is its copolymerization with several vinyl monomers.     

Complete transligation of (AcO)4Rh2 applied onto λ-Al2O3 with 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane

Complete transligation of (AcO)₄Rh₂ with 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane was conducted in the solid phase on λ-Al₂O₃. The reduction of Rh¹¹ to Rh^I on λ-Al₂O₃ at 130°C under the actionof the above-mentioned bicyclic phosphite is accompanied by the oxidation of the acetate anion to the acetoxyl radical. The oxidation products were detected by IR and ESR spectroscopy. 2,6-Di-tert-butyl-4-methylphenol was used as a “spin trap” to identify stable secondary radical cations. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 2036–2038, October, 1998.     

A stereoselective synthesis of 3-substituted (S)-pyroglutamic and glutamic acids via OBO ester derivatives

(S)-Pyroglutamic acid is transformed to the Cbz-protected 4-methyl-2,6,7-trioxabicyclo[2.2.2] octane (OBO) ester. This ortho ester functionality is employed as a bulky steering group for stereoselective introduction of alkyl and aryl groups via 1,4-cuprate addition to 3,4-unsaturated pyroglutamates. After deprotection and ringopening, 3-substituted glutamic acids are obtained.     

具有可逆热致变色有机-无机杂化铜化合物的合成及表征

在浓盐酸水溶液中，碘化N，N-二甲基-1，5-二氮杂环[3.2.1]辛烷（[3.2.1-Me₂dabco]I₂）和碘化1-氨基-1，4-二氮杂环[2.2.2]辛烷（[2.2.2-NH₂dabco]I）与氯化铜反应得到2种有机-无机杂化铜化合物[3.2.1-Me₂dabco][CuCl₄]（1）和[2.2.2-NH₂dabco][CuCl₄]（2）。X射线单晶结构衍射证实化合物1和2中的无机阴离子是[CuCl₄]^2-四面体。化合物1和2表现出可逆的热致变色现象，随着温度升高，它们的颜色从黄色变为红色，这应该是由[CuCl₄]^2-四面体的变形引起的。     

Synthesis and Structure of A Novel Caged Bicyclic Phosphate Flame Retardant

IntroductionThe ecological safety of polymer flame retardant has become a major subject in the modern polymer industry, and there is an international demand for the control of polymer flammability without the use of halogenated additives. Consequently, current research is mainly focused on looking for environmental friendly additives in the form of organophosphorus compounds, which are being thought as the alternatives of the halogen containing flame retardants1. Among the organophosphorus fla…     

A new three‐dimensional CdII supramolecular framework constructed from the 1‐[(1H‐tetrazol‐5‐yl)methyl]‐1,4‐diazoniabicyclo[2.2.2]octane ligand

A new tetrazole–metal supramolecular compound, di‐μ‐chlorido‐bis(trichlorido{1‐[(1H‐tetrazol‐5‐yl‐κN²)methyl]‐1,4‐diazoniabicyclo[2.2.2]octane}cadmium(II)), [Cd₂(C₈H₁₆N₆)₂Cl₈], has been synthesized and structurally characterized by single‐crystal X‐ray diffraction. In the structure, each Cd^II cation is coordinated by five Cl atoms (two bridging and three terminal) and by one N atom from the 1‐[(1H‐tetrazol‐5‐yl)methyl]‐1,4‐diazoniabicyclo[2.2.2]octane ligand, adopting a slightly distorted octahedral coordination geometry. The bridging bicyclo[2.2.2]octane and chloride ligands link the Cd^II cations into one‐dimensional ribbon‐like N—H...Cl hydrogen‐bonded chains along the b axis. An extensive hydrogen‐bonding network formed by N—H...Cl and C—H...Cl hydrogen bonds, and interchain π–π stacking interactions between adjacent tetrazole rings, consolidate the crystal packing, linking the poymeric chains into a three‐dimensional supramolecular network.     

Synthese und Struktur von Hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octan – Eine neue Käfigverbindung mit dem Sn(P2)3Sn-Gerüst

Synthesis and Structure of Hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octane – a New Cage Compound with the Sn(P₂)₃Sn Skeleton The reaction of the diphosphide K₂[(tBuP)₂] 1 with SnCl₄ leads by a redox process mainly to (tBuP)_3,4 and other sideproducts. However, at the same time a threefold [2 + 1]-cyclocondensation reaction takes place yielding the new cage compound hexa-t-butyl-1,4-dichloro-1,4-distanna-2,3,5,6,7,8-hexaphosphabicyclo[2.2.2]octane, ClSn(tBuP? PtBu)₃SnCl 2 . 2 could be obtained in a pure form and characterized ³¹P and ¹¹⁹Sn NMR spectroscopically; 2 was also characterized by a single crystal structure analysis.     

Reduction potential as a measure of activity of the N-F fluorinating agents

The possibility of evaluating activity of fluorinating agents by their electrochemical characteristics is confirmed by the example ofN-fluorobenzenesulfoneimide (I), as well as l-chlormethyl-4-fluoro-l,4-diazoniumbicyclo [2.2.2]octane (II) and l-hydroxy-4-fluoro-l,4-diazoniumbicyclo[2.2.2]octane (III) ditetrafluoroborates. The half-wave potentialE _1/2 of reduction on a rotating platinum electrode is the best activity measure. CompoundsII andIII, being very reactive fluorinating agents, are characterized by positiveE _1/2. Compound I, which has moderate reactivity, reduces at much more negative potentials.     

Cationic polymerization of 1-phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane

Cationic polymerization of bicyclo ortho ester, 1-phenyl-4-ethyl-2,6,7-trioxabicyclo[2.2.2]octane, was carried out with Lewis acids and cation sources to obtain the polyether containing ester group in the side chain. It was found that boron trifluoride etherate was the most active initiator in the Lewis acids. Magnesium perchlorate and triphenylcarbenium tetrafluoroborate, which have lower nucleophilic counter ions, initiated effectively the polymerization of bicyclo ortho ester.     

In Situ Observation of Ferroelastic Domain and Phase Transition in a Three-Dimensional Molecular Crystal

Massive efforts have been devoted to designing molecular ferroic materials by molecular modification. For molecular ferroelastic, previous work is focused on the temperature-dependent ferroelastic domains, however, few are related to controlling the ferroelastic domain by the stress. Inspired by the “quasi-spherical theory” and fluorination effect, we designed a more flexible (MedabcoF)²⁺ (MedabcoF=1-fluoro-4-methyl-1,4-diazoniabicyclo[2.2.2]octane) cation by introducing a methyl group and a fluorine atom at the two symmetrical ends of the Dabco (1,4-diazoniabicyclo[2.2.2]octane) and synthesized a hybrid 3D perovskite (MedabcoF)Rb(BF₄)₃ ( 1 ) which displays three reversible phase transitions accompanying dual ferroelastic behavior. Besides, it not only exhibits ferroelastic domains switching by the thermal stimulation, and the sensitive reaction of in situ domains under the stress of it is also realized. This work not only achieves a force-controlled ferroelastic domain but develops a more profound comprehension of the relationship between the thermal motion behavior of guest cations and the intriguing properties of materials.     

Conformational analysis of 4-methyl-2-trimethylsiloxy-1,3,2-dioxaphosphinane

Conformational analysis of 4-methyl-2-trimethylsiloxy-1,3,2-dioxaphosphinane was performed by the dipole moment method and quantum-chemical calculations. The 1,3,2-dioxaphosphinane heteroring was found to adopt a chair conformation with equatorial orientation of the 4-methyl group and axial orientation of the irregular trimethylsiloxy substituent. The conformational equilibrium involves non-eclipsed gauche and trans conformers (the latter prevailing) interconvertible through rotation about the exocyclic P-O bond.     

A two‐dimensional cadmium(II) coordination polymer based on 1‐cyanomethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane and thiocyanate ligands

A cadmium–thiocyanate complex, poly[(1‐cyanomethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane‐κ⁴N)octakis‐μ₂‐thiocyanato‐κ⁸N:S;κ⁸S:N‐tricadmium(II)], [Cd₃(C₈H₁₄N₃)₂(NCS)₈]_n, was synthesized by the reaction of 1‐cyanomethyl‐4‐aza‐1‐azoniabicyclo[2.2.2]octane chloride, cadmium nitrate tetrahydrate and potassium thiocyanide in aqueous solution. In the crystal structure, there are two independent types of Cd^II cation (one on a centre of inversion and one in a general position) and both are in distorted octahedral coordination environments, coordinated by N and S atoms from different ligands. Neighbouring Cd^II cations are linked together by thiocyanate bridges to form a two‐dimensional network. Hydrogen‐bonding interactions are involved in the formation of a three‐dimensional supramolecular network.     

Pyrimidine derivatives XII. A convenient preparation of 6-formylpyrimidinedione and 2- and 3-formylpyridine derivatives from corresponding nitrooxymethyl derivatives

The convenient preparation of 6-fomylpyrimidinedione derivatives and 2- and 3-formylpyridine are described. Thus, 5-bromo-1,3-dimethyl- ( 1a ), 5-bromo-3-methyl-1-(2-nitrooxyethyl)- ( 1b ), and 5-bromo-3-methyl-1-(3-nitrooxypropyl)-2,4(1H,3H)-pyrimidine-dione ( 1c ) were converted to the corresponding 6-formyl compounds 2a, 2b , and 2c , respectively, in excellent yields by the reaction with triethylamine and 1,4-diazabicyclo[2.2.2]octane. These 6-formylpyrimidinedione derivatives are key intermediates for the preparation of 6-carbon-carbon substituted compounds, which are expected to be potential antitumor and antiviral agents. Similarly, 2-(and 3-)formylpyridine ( 9a (and 9b )) were obtained by the reaction of 2-(and 3)nitrooxymethylpyridine ( 8a (and 8b )) with 1,4-diazabicyclo[2.2.2]octane.     

Interaction between Exocyclic s-cis-Butadiene and Homoconjugated Functions. Preparation and Diels-Alder Reactivity of Remotely Substituted 2,3-Dimethylidenebicyclo[2.2.2]octanes

The preparations of 5,6-dimethylidene-2exo-bicyclo[2.2.2]octanol ( 8 ), its endo isomer 9 , 5,6-dimethylidene-2-bicyclo[2.2.2]octanone ( 10 ) and 2 exo, 3 exo-epoxy-5,6dimethylidenebicyclo[2.2.2]octane ( 11 ) are described. The kinetics of their cycloaddition to tetracyanoethylene has been measured in toluene at 25° together with those of 2,3-dimethylidenebicyclo[2.2.2]octane ( 7 ) and 5,6-dimethylidenebicyclo[2.2.2]oct-2-ene (12). The effects of remote substitution on the Diels-Alder reactivity of 2,3-dimethyl idenebicyclo[2.2.2]octanes are compared with those observed in the 2,3-dimethylidenenorbornane series ( 1–6 ).     

Electron impact induced fragmentation of 4-alkyl derivatives of 2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane and the corresponding 1-oxides, 1-sulfides and 1-selenides

The electron impact fragmentations of several derivatives of 2,6,7-trioxa-1-phosphabicyclo[2.2.2]octane have been examined by means of high resolution and metastable ion analysis. The principal fragmentation route for bicyclophosphites, phosphates and phosphorothionates involves a loss of formaldehyde, followed by a loss of the PO₂X and HPO₂X groups (X = -, O, S). The behaviour of phosphoroselenates is quite different, due partly to the favoured loss of selenium from the molecular ion before further fragmentation. Fragmentation through C? O bond breaking and a rearranged molecular ion is dependent on the exocyclic chalcogen atom (-, O, S, Se) on phosphorus. The reactions have been rationalized in terms of 1- and 4-substitutions.     

Functionalization of one or two methyl groups in the [Cp*<Subscript>2</Subscript>RuBr]<Superscript>+</Superscript>Br<Superscript>−</Superscript> complex in the reaction with bromine

The reaction of [Cp*₂RuBr]⁺Br⁻ with bromine in CH₂Cl₂ (CD₂Cl₂) in an inert atmosphere at room temperature produces the complexes [Cp*Ru(Br)C₅Me₄CH₂Br]⁺Br₃ ⁻ (syn conformer), [Cp*Ru(Br)C₅Me₃(CH₂Br)₂]⁺ (syn and anti conformers), and [Ru(Br)(C₅Me₄CH₂Br)₂]⁺ (syn conformer). All complexes were characterized by ¹H and ¹³C NMR spectroscopy; the former complex, by elemental analysis. These complexes were also prepared by the reaction of [Cp*RuC₅Me₄CH₂]⁺BF₄ ⁻ with bromine in CH₂Cl₂. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 12, pp. 2712–2718, December, 2005.     

A facile one-pot synthesis of α-fluoro-α,β-unsaturated esters from alkoxycarbonylmethyltriphenylphosphonium bromides

A convenient one-pot synthesis of α-fluoro-α,β-unsaturated esters from ethoxy- and tert-butoxycarbonylmethyltriphenylphosphonium bromide was developed. The fluorinated phosphoranes, generated in situ from alkoxycarbonylmethyltriphenylphosphonium bromides and 1-chloromethyl-4-fluoro-1,4-diazoniabicyclo[2.2.2]octane bis(tetrafluoroborate) (Selectfluor^®), undergo a Wittig reaction with aldehydes to yield α-fluoro-α,β-unsaturated esters with (Z)-selectivity.