Carbyne-fluoro complexes of rhenium. Single-pot synthesis of trans-[ReF(CCH2R)-(Ph2PCH2CH2PPh2)2][BF4]

Treatment of a THF solution of trans-[ReCl(N₂)(dppe)₂] (dppe = Ph₂PCH₂CH₂PPh₂) with a 1-alkyne HCCR (R =^tBu, CO₂Me, CO₂Et, or C₆H₄Me-4), in the presence of Tl[BF₄]/[NH₄][BF₄], under sunlight, affords the corresponding carbyne-fluoro complexes trans-[ReF(CCH₂R)(dppe)₂][BF₄] in an unprecedented single-pot synthesis. Further reaction with [BU₄N]OH leads to the vinylidenefluoro compounds trans-[ReF(=C=CHR)(dppe)₂] (R = CO₂Me, CO₂Et, or C₆H₄Me-4).     

Insertion Reactions of [ReH(CO)5–n(PMe3)n] Complexes (n = 2–4) with aldehydes,CO2, and activated acetylenes

The complexes of the type [ReH(CO)_5–n(PMe₃)_n] (n = 4, 3) were reacted with aldehydes, CO₂, and RC?CCOOMe (R = H, Me) to establish a phosphine-substitutional effect on the reactivity of the Re–H bond. In the series 1–3 , benzaldehyde showed conversion with only 3 to afford a (benzyloxy)carbonyltetrakis(trimethylphosphine)rhenium complex 4 . Pyridine-2-carbaldehyde allowed reaction with all hydrides 1–3 . With 1 and 2 , the same dicarbonyl[(pyridin-2-yl)methoxy-O, N]bis(trimethylphosphine)rhenium 5b was formed with the intermediacy of a [(pyridin-2-yl)methoxy-O]-ligated species and extrusion of CO or PMe₃, respectively. The analogous conversion of 3 afforded the carbonyl[(pyridin-2-yl)methoxy-O,N]tris(trimethylphosphine)rhenium ( 1 ) 7b . While 1 did not react with CO₂, 2 and 3 yielded under relatively mild conditions the formato-ligated [Re(HCO₂)(CO)(L)(PMe₃)₃] species ( 8 (L = CO) and 9 (L = PMe₃)). Methyl propiolate and methyl butynoate were transformed, in the presence of 1 , to [Re{C(CO₂Me)?CHR}(CO)₃(PMe₃)₂] systems ( 10a (R = H), and 10b (R = Me)), with prevailing α-metallation and trans-insertion stereochemistry. Similarly, HC≡CCO₂Me afforded with 2 and 3 , the α-metallation products [Re{C(CO₂Me)?CH₂}(CO)(L)(PMe₃)₃] 11 (L = CO) and 12 (L = PMe₃). The methyl butyonate insertion into 2 resulted in formation of a mixture of the (Z)- and (E)-isomers of [Re{C(CO₂Me)?CHMe} (CO)₂(PMe₃)₃] ( 13a , b ). In the case of the conversion of 3 with MeC?CCO₂Me, a Re–H cis-addition product [Re{(E)-C(CO₂Me)?CHMe}(CO)(PMe₃)₄] ( 14 ) was selectively obtained. Complex 11 was characterized by an X-ray crystal-structure analysis.     

Evidence for σ-π interaction in some allyltin compounds. UV photoelectron spectroscopy and LCBO calculations

A series of allyltin compounds, R_3-nCl_nSnCH₂CH=CH₂ (R = Me, n-Bu; n = 0-2) and Ph₃SnCH₂CH=CH₂, have been studied by gas-phase UV photoelectron spectroscopy, in order to determine the extent, if any, of σ-π conjugation (hyper-conjugation) between the σ(SnCH₂) bond and the π(CC) orbital of the allyl group. Analysis of the spectra, supported by a fragment analysis based on LCBO (Linear Combination of Bond Orbitals) calculations, indicated that the hyperconjugation operates for all the members of the series, the extent decreasing on passing from R = Me to R = n-Bu and, within each series, with increasing n.     

Synthesis and Optoelectronic Properties of Hexahydroxylated 10‐O‐R‐Substituted Anthracenes via a New Modification of the Friedel–Crafts Reaction Using O‐Protected ortho‐Acetal Diarylmethanols

A new modification of the Friedel–Crafts type intramolecular cyclization involving O‐protected ortho‐acetal diarylmethanols as a new type of reactant, was carried out for the first time in a medium containing a large amount of water at room temperature and enabled synthesis of a series of electron‐rich, hexahydroxylated 10‐O‐R‐substituted anthracenes, where R is an alkyl (Me, nBu, n‐C₁₆H₃₃) or arylalkyl group (CH₂Ph, CH₂‐2‐Napht, CH₂C₆H₄CH₂OAr) and also evaluation of their electronic and optoelectronic properties in solution, crystal, and solid thin film. In this transformation, a central 10‐O‐R‐substituted benzene ring was formed, fused to rings originating from two independent aromatic aldehydes. The reaction proceeded via two identified mechanisms involving acetal and/or free aldehyde groups. The acid sensitive acetal and dibenzyl alkoxy functions have never been used together in the intramolecular Friedel–Crafts type cyclization. The new compounds revealed deep blue fluorescence and quantum yields in solution around 0.3. The electrical properties investigated for thin films obtained by vacuum deposition on glass were 10‐O‐R‐substituent dependent and showed much faster transient current decay in the case of the 10‐O‐CH₂Ph derivative than for the material with a 10‐O‐Me substituent (the lifetime of charge carriers was 25 times shorter in this case). The AFM images of thin films, Stokes shifts, and X‐ray analysis of π‐stacking interactions in crystals of the new materials have been also obtained.     

Living cationic polymerization route to poly(oligooxyethylene carbonate) vinyl ethers

The addition of dialkyl (R = Me or Et) carbonates to poly(oxyethylene)-based solid polymeric electrolytes resulted in enhanced ionic conductivities. Relatively high conductivities in lithium batteries with solutions of lithium salts in di(oligooxyethylene) carbonates such as R( OCH₂ CH₂ )_nOC(O) O ( CH₂CH₂O )_mR (R = Et, n = 1, 2, or 3, m = 0, 1, 2, or 3) and related carbonates were obtained. In this respect, related comb-shaped poly(oligooxyethylene carbonate) vinyl ethers of the type  CH₂CH(OR) were prepared [R = ( OCH₂ CH₂ )_nOC(O) O ( CH₂CH₂O )_mR′; (1) n = 2 or 3, m = 0, R′ = Et; (2) n = 2 or 3; m = 3, R′ = Me]. The direct preparation of derived target polymers of this class by polymerization of the corresponding vinyl ether-type monomers could not be achieved because of a rapid in situ decarboxylative decomposition of these monomers (as formed) during the final step of their synthesis. Instead, a prepolymer was prepared by a living cationic polymerization of CH₂CH (OCH₂CH₂ )_n O C(O) CH₃ (n = 2 or 3). The hydrolysis of its pendant ester groups, followed by the reaction of the hydrolyzed prepolymer with each of several alkyl chloroformates of the type Cl C(O) O( CH₂CH₂O )_mR′ (m = 0, 2, or 3, R′ = Me or Et) resulted in the corresponding target polymers. © 2002 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 40: 2171–2183, 2002     

Synthetic and mechanistic aspects of metal-free polymerizations of acrylates

Metal-free initiators are easily prepared from neutral CH- and NH-acidic compounds such as malonic acid esters, nitriles, sulfones, nitro-alkanes, cyclopentadiene, fluorene derivatives, carbazoles and succinimide. These anions have tetrabutylammonium ions as cationic counterions, but they are not completely free “naked” anions as traditionally assumed. Rather, anion and cation are intimately connected to each other via H-bonds. These salts initiate the polymerization of acrylates, methacrylates and acrylonitrile, forming polymers in the MW range of 1500 to 20000 with narrow molecular weight distributions (D = 1.1–1.4) in optimized cases. A completely different approach involves initiators of the type α-iodo malonic acid esters CH₃C(I)(CO₂R)₂ and α- iodo isobutyric acid esters (CH₃)₂C(I)CO₂R in combination with (nBu)₄N⁺I⁻ at 60°C. This novel initiator system is specific for metharcylates, i. e., acrylates are not polymerized.     

Preparation and stereochemistry of methyl 3-(and 4)-p-chlorothiophenoxy-1-methylpiperidine-4-(and 3)-carboxylates,and cyclization to benzothiopyranopyridinones

The title piperidines were prepared by (a) methanolysis of the corresponding nitriles and (b) addition of p-chlorothiophenol to the appropriate tetrahydropyridines. Three esters were obtained with stereochemistry assigned by nmr analysis: 2 [3(a) SAr, 4(e) CO₂Me], 5 [4(e) SAr, 3(e) CO₂Me], 6 [4(a) SAr, 3(e) CO₂Me]. Compounds 2 and 6 cyclized in 70% sulfuric acid. The product structures were established by X-ray crystallography and, surprisingly, both had trans-fused rings. Compound 5 , however, did not cyclize but gave 4-(methylthio)chlorobenzene as the sole isolated product.     

Metal complexes of ligands containing intercalating units. Synthesis of nickel(II), copper(II), rhodium(II), and platinum(II) complexes with diamine-substituted acridines and quinolines,and with mitonafide [N-(2,2-dimethylaminoethyl)-3-nitro-1, 8-naphthalimide] and related ligands

Summary The preparations and characterisation are reported of a range of complexes of Ni^II, Cu^II, Rh^II, and Pt^II with 6-chloro-2-methoxyacridine substituted in the 9-position with –NH(CH₂)_nNR₂ groups (where n=2 or 3, R=H or Me), and of complexes with 7-chloroquinoline analogously substituted in the 4-position. The preparations are also reported of complexes of the types [Rh(CH₃CO₂)₂L]₂, Cu(CH₃CO₂)₂L₂, PtL₂Cl₂, and (LH)₂[PtCl₄], where L=N-(2,2-dimethylaminoethyl)-3-nitro-1, 8-naphthalimide (mitonafide) and/or its 2,2-aminoethyl-, 2,2-aminopropyl-, or 2,2-dimethylaminopropyl analogues. Initial cytotoxicity studies are reported for some of the Pt compounds.     

P(RNCH2CH2)3N: AN EFFICIENT PROMOTER FOR THE SYNTHESIS OF 3-SUBSTITUTED COUMARINS

ABSTRACT

The title compounds wherein R = Me or i-Pr function as efficient promoters for the formation of coumarins in good to excellent yields (80–95%) from salicylaldehydes and di-activated methylene compounds of the type R′CH₂CO₂Et (R′ = CO₂Et, COMe, CN). Although the yields are not generally superior to those reported in the literature, our methodology is more convenient in that milder conditions and shorter reaction times are facilitated by the use of the aforementioned commercially available catalysts.     

The rate constants for the addition of radicals CCl3CH2·CHR (R = Ph,CO2Me,CONC4H8) to some unsaturated compounds

The rate constants for the addition of radicals CCl₃CH₂ ^·CHR to unsaturated compounds CH₂=CHR (R = Ph, CO₂Me, CONC₄H₈) and to CH₂=CMeCO₂Me were determined at 22 °C by ESR spectroscopy.     

Etude de la réactivité du fluorure de potassium sur des esters polyhalogénés

Reactions of polyhalogenated esters with potassium fluoride in polar solvents have been studied. Two kinds of reactions are possible depending on the starting compound: the hydrochlorinated estersRCCl₂CH₂CHR′CO₂CH₃ (R=Cl, -CF₃ ; R′=H, -CH₃ give the corresponding α-β unsaturated derivatives. Moreover when using ethylene glycol as a solvent, a transesterification reaction occurs after the dehydrohalogenation. From perhalogenated esters, mainly decarboxylation products are formed; for example in DMSO as a solvent, the fluorination of the telomers Cl-(CFClCF₂)_n-CO₂CH₃ yields the corresponding perfluoroalkenes C_2nF_4n. Some mechanistic interpretations are given in order to explain the formation of the different compounds.     

Fragmentation of some 4<Emphasis Type="Italic">H</Emphasis>-pyran-4-one and pyridin-4-one derivatives under electron impact

Fragmentation of 13 compounds of the 4H-pyran-4-one and pyridin-4-one series under electron impact involves formation of rearrangement ions stabilized by multiple bonds and oxygen atoms (mostly [RC≡O]⁺ and RCH=OR′]⁺), as well of neutral molecules with low enthalpies of formation (CO, H₂O, CH₂O, CO₂, CH₂=C=O, C₃O₂, and RCOOH; R = H, Me, HC≡C, HOC≡C).     

Phenyl(acyloxy)fluorosilanes C6H5Si(OCOR)nF3?n (n = 1, 2) and phenyl(acyloxy)fluorochlorosilanes C6H5Si(OCOR)FCl

The method of synthesis of the hitherto unknown class of organosilicon compounds, phenyl(acyloxy)fluorosilanes C₆H₅Si(OCOR) _n F_3−n (n = 1, 2) and phenyl(acyloxy)fluorochlorosilanes C₆H₅Si(OCOR) FCl in up to 91% yield has been developed based on the reaction of phenyl(fluoro)chlorosilanes C₆H₅SiCl _n F_3−n (n = 1, 2) with trimethylsilyl esters of carboxylic acids Me₃SiOC(O)R [R = H, CH₃, CF₃, CCl₃, ClCH₂, BrCH₂, CH₂=CHCH₃, CH₂=CHPh, CH(CH₃)=CH₂, Ph].     

Silicon‐ and Tin‐Containing Open‐Chain and Eight‐Membered‐Ring Compounds as Bicentric Lewis Acids toward Anions

Herein, we report the syntheses of silicon‐ and tin‐containing open‐chain and eight‐membered‐ring compounds Me₂Si(CH₂SnMe₂X)₂ ( 2 , X=Me; 3 , X=Cl; 4 , X=F), CH₂(SnMe₂CH₂I)₂ ( 7 ), CH₂(SnMe₂CH₂Cl)₂ ( 8 ), cyclo‐Me₂Sn(CH₂SnMe₂CH₂)₂SiMe₂ ( 6 ), cyclo‐(Me₂SnCH₂)₄ ( 9 ), cyclo‐Me_(2?n)X_nSn(CH₂SiMe₂CH₂)₂SnX_nMe_(2?n) ( 5 , n=0; 10 , n = 1, X= Cl; 11 , n=1, X= F; 12 , n=2, X= Cl), and the chloride and fluoride complexes NEt₄[cyclo‐ Me(Cl)Sn(CH₂SiMe₂CH₂)₂Sn(Cl)Me?F] ( 13 ), PPh₄[cyclo‐Me(Cl)Sn(CH₂SiMe₂CH₂)₂Sn(Cl)Me?Cl] ( 14 ), NEt₄[cyclo‐Me(F)Sn(CH₂SiMe₂CH₂)₂Sn(F)Me?F] ( 15 ), [NEt₄]₂[cyclo‐Cl₂Sn(CH₂SiMe₂CH₂)₂SnCl₂?2 Cl] ( 16 ), M[Me₂Si(CH₂Sn(Cl)Me₂)₂?Cl] ( 17 a , M=PPh₄; 17 b , M=NEt₄), NEt₄[Me₂Si(CH₂Sn(Cl)Me₂)₂?F] ( 18 ), NEt₄[Me₂Si(CH₂Sn(F)Me₂)₂?F] ( 19 ), and PPh₄[Me₂Si(CH₂Sn(Cl)Me₂)₂?Br] ( 20 ). The compounds were characterised by electrospray mass‐spectrometric, IR and ¹H, ¹³C, ¹⁹F, ²⁹Si, and ¹¹⁹Sn NMR spectroscopic analysis, and, except for 15 and 18 , single‐crystal X‐ray diffraction studies.     

Trimethylene-bridged Tetraorganodistannoxanes {[Me3SiCH2(RCOO)Sn(CH2)3Sn(OOCR)CH2SiMe3]O}n (R = Ph, 2,4-Me2C6H3): Control of Structure by Variation of R

The synthesis of trimethylene-bridged carboxylate-substituted tetraorganodistannoxanes {[Me₃SiCH₂(RCOO)Sn(CH₂)₃Sn(OOCR)CH₂SiMe₃]O} _n (1, R = Ph; 2, R = 2,4-Me₂C₆H₃) is reported. Depending on the structure of R, in the solid state these compounds are either dimers (1, n = 2, cis-isomer) with a ladder-type structure or tetramers (2, n = 4) with a double ladder-type structure.     

Alkyl- und Arylkomplexe des Iridiums und Rhodiums. XIX. Reaktion von Carbonsäuren mit ausgewählten Organoverbindungen von Ir(I) und Rh(I): Bildung von Arylhydrido-, Carboxylatohydrido- und Carboxylato-Derivaten

Alkyl and Aryl Complexes of Iridium and Rhodium. XIX. Reaction of Carboxylic Acids with Selected Organo Compounds of Ir(I) and Rh(I): Formation of Arylhydrido, Carboxylatohydrido, and Carboxylato Derivatives cis-Arylhydridoiridium(III) complexes IrH(Ar)(O₂CR)(CO)(PPh₃)₂ (R = Me: Ar = C₆H₅, 4-MeC₆H₄; R = Et: Ar = 4-MeC₆H₄, 2,4-Me₂C₆H₃) could be prepared by oxidative addition of carboxylic acids to aryliridium(I) compounds Ir(Ar)(CO)(PPh₃)₂. Reaction of aliphatic carboxylic acids with alkyliridium(I) derivatives Ir(Alk)(CO)(PPh₃)₂ and Ir(Alk)[PhP(CH₂CH₂CH₂PPh₂)₂] (Alk = CH₂CMe₃, CH₂SiMe₃) lead to dicarboxylatoiridium(III) hydrides IrH(O₂CR)₂(CO)(PPh₃)₂ (R = Me, Et, i-Pr) and IrH(O₂CR)₂[PhP(CH₂CH₂CH₂PPh₂)₂] (R = Me, Et). Ir(4-MeC₆H₄CO₂)(CO)(PPh₃)₂ was obtained from Ir(CH₂SiMe₃)(CO)(PPh₃)₂ and 4-MeC₆H₄CO₂H. Interaction of organorhodium complexes Rh(R′)(CO)(PPh₃)₂ (R′ = CH₂SiMe₃, 4-MeC₆H₄) and Rh(R′)[PhP(CH₂CH₂CH₂PPh₂)₂] (R′ = CH₂CMe₃, 4-MeC₆H₄) with aliphatic and aromatic carboxylic acids yielded carboxylatorhodium(I) compounds Rh(O₂CR)(CO)(PPh₃)₂ (R = Me, t-Bu, 4-MeC₆H₄) and Rh(O₂CR)[PhP(CH₂CH₂CH₂PPh₂)₂] (R = Me, 4-MeC₆H₄).     

Reactivity of Bridged Pentelidene Complexes with Isonitriles: A New Way to Pentel‐Containing Heterocycles

The reaction of [Cp*E{W(CO)₅}₂] (E=P ( 1 a ), As ( 1 b ); Cp*=1,2,3,4,5‐pentamethylcyclopentadienyl) with isonitriles RNC (R=tBu, cyclohexyl (Cy), nBu) depends on the steric demand of the substituent at the isonitrile as well as on the stoichiometry of the starting materials. With tBuNC only the Lewis acid/base adducts [Cp*E{W(CO)₅}₂(CNtBu)] (E=P ( 2 a ), As ( 2 b )) are formed. The use of Cy and n‐butylisonitrile leads first to the formation of the Lewis acid/base adduct, but only at low temperatures. At ambient temperatures, a rearrangement occurs and bicyclo[3.2.0]heptane derivatives of the type [{C(Me)C(CH₂)C(Me)C(Me)C(Me)}C(NR)‐ E{W(CO)₅}₂] (E=P, As; R=Cy, nBu) ( 3 a‐Cy , 3 b‐Cy , 3 a‐nBu and 3 b‐nBu ) are obtained. The use of a further equivalent of isonitrile results in products revealing two new structural motifs, the four‐membered ring derivatives [C(Cp*)N(R)C(NR)E{W(CO)₅}₂] ( 4 : E=P, As; R=Cy, nBu) and the bicyclic complexes [[{C(Me)C‐ (CH₂)C(Me)C(Me)C(Me)}C(NR)₂‐ E{W(CO)₅}₂] ( 5 : E=As; R=Cy). The reaction pathway depends on the substituent at the isonitrile. By treatment of 1 a with two equivalents of CyNC only a 2H‐1,3‐azaphosphet complex 4 a‐Cy (E=P; R=Cy) is formed. Treatment of 1 b with two equivalents of CyNC exclusively leads to the complex 5 b‐Cy (E=As; R=Cy). Treatment of 1 a with two equivalents of nBuNC results in a mixture of complexes, the 2H‐1,3‐azaphosphet 4 a‐nBu (E=P; R=nBu) and the bicyclic complex 5 a‐nBu (E=P; R=nBu). For the arsenidene complex 1 b a mixture of the 2H‐1,3‐azarsete complex 4 b‐nBu (E=As; R=nBu) and the bicyclic complex 5 b‐nBu (E=P, As; R=Cy, nBu) is obtained. Complex 4 b‐nBu is the first example of a 2H‐1,3‐azarsete complex. All products have been characterized by using mass spectrometry, NMR spectroscopy, and X‐ray diffraction analysis.     

Electrosynthesis of esters of mono- and dioxoalkanoic and alkanedioic acids on the basis of nitro-substituted alkyl carboxylates and cycloalkanones

A one-pot electrochemical method for the synthesis of methyl monooxoalkanoates with the carbonyl group in position 4, methyl dioxoalkanoates with the oxo groups in positions 4,7-, 6,9-, 7,10-, and 12,15, and methyl 4-oxoalkanedioates was developed. This method is based on amperostatic electrolysis in an undivided cell of the salts of esters of nitroalkaniic acids and their adducts with CH₂=CHX (X = Ac, CO₂Me).     

Fast atom bombardment mass spectrometry of some alkoxv- and chloro-silanes

The positive and negative FAB mass spectra of a series of alkoxy- and chloro-silanes X_m(CH₃)₃-_mSi(CH₂)_nR [m = 1 or 3, n = 3, 10 or 17, X = Cl or OMe or OEt, R = Me, NH₂, glycidoxy, COOMe, NHCO(CH₂)₇COOMe or NHCO(CH₂)₁₀CH₂OAc] were recorded in NBA and NPOE matrices. The chlorosilanes underwent rapid hydrolysis into silanols which condense to form siloxanes, the process being complete in NBA and partial in NPOE, yielding siloxane-based fragment ions in the positive spectra and silyloxyanions in the negative spectra. The alkoxysilanes were more resistant to hydrolysis, affording abundant [MH – HX]⁺ ions (X = OMe or OEt) in their positive FAB spectra and moderate to high intensity [M – H]^? ions in the negative mode, the latter undergoing characteristic sequential loss of C₂H₄, EtOH and C₂H₄. Significant variations were observed in the positive spectra of all the silanes with change of matrix.     

Acyl Iodides in Organic Synthesis: I. Reactions with Alcohols

Reaction of acyl iodides RC(O)I (R = Me, Ph) with alcohols R'OH (R' = Me, Et, i-Pr, t-Bu, CH₂ = CHCH₂, HCCCH₂) provides in the corresponding organyl iodides R'I. Unlike that 2-chloroethanol and phenol (R' = CH₂CH₂Cl, Ph) react with RC(O)I in the same way as with acyl chlorides yielding esters RCO₂R'. This reaction path occurs partially also with methanol and ethanol.