The reaction of α-stannylmethyllithium with esters

Ketonic compounds were prepared from esters using α-stannylmethyllithium as the reagent.     

Specific features of “compensating” copolymerization of butyl acrylate with vinyl butyl ether in the presence of triethylboron

Copolymerization of butyl acrylate with a large excess of boiling vinyl butyl ether was carried out in the presence of triethylborane. The analysis of the composition of the obtained product demonstrated that an alternating low-molecular-weight copolymer was predominantly formed. The formation of macromolecules occurred by both conventional and controlled radical polymerization (CRP), as evidenced by a bimodal molecular weight distribution. As conversion increased, the mode corresponding to the CRP mechanism shifted toward larger molecular masses. The relative activities of comonomers for the process initiated by triethylborane were calculated.     

Studies on the reaction of α-imino esters with organometallic compounds

Benzylzinc reagent reacted with α-imino ester (2) at the α-carbon exclusively, though other organometallic reagents such as Mg. Al, Cu, Tl, and B derivatives reacted at the nitrogen atom. Use of the (S)-amine as a chiral auxiliary of 2 created the R chirality at the imino carbon. Very high chiral Induction was realized In the reaction of prenylzinc reagent wlih α-imino 8-(-)phenylmenthyl ester (10). The reaction of 2 with heteroatom substituted allylic organometalic compounds (15) gave the corresponding α-heterostom substituted amino acid derivatives (16). Here again, the allylic zinc reagent gave the adduct in higher yield than the corresponding Tl, Al, and B reagents.     

The reaction of carbohydrate-derived alkoxyaldehydes with methoxycarbonylmethylenetriphenylphosphorane: stereoselective synthesis of β-unsaturated esters

The reaction of several carbohydrate-derive alkoxyaldehydes with methoxycarbonylmethylenetriphenylphosphorane afford α, β-unsaturated esters with Z-stereoselectivity. The stereoselectivity depends on the substrate stucture and the nature of the solvent used.     

Triarylaminium salt facilitated Friedel–Crafts reaction of indoles with enamides and vinyl ethers

Commercially available stable radical cation triarylaminium salt can be used as an efficient initiator for Friedel–Crafts reaction of indoles with enamides to regioselectively construct complex indole derivatives and for double Friedel–Crafts reaction of indoles with vinyl ethers to offer 3,3′-Bis(indolyl)alkane derivatives. The ready availability of the starting materials and the usefulness of the products make this strategy attractive.     

Thiocyanatocarbonyl compounds. The reaction of phosphoryl-α-thio-cyanatoacetaldehydes and their acetals with diethylamine

The reactions of phosphorylated α-thiocyanatoacetaldehydes and their acetals with diethylamine were studied for the first time. These reactions result in the synthesis of C-phosphorylated thiazolidine rings. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 124-130, January, 2009.     

The reaction of carbohydrates and uronic acids with β-methylindole

Aldo- and ketu-hexoses produce with β-methylindole a pigment that is soluble with blue color in chloroform. The same applies to ω-hydroxymethylfurfural. Pentoses and uronic acids as well as furfural produce an olive color reaction, but no blue Soluble pigment. Methylpentoses and methylfurfural produce a red pigment, the chloroform extract of which is of raspberry color. The behavior of the heptoses is not characteristic. There is no possibility of differentiating between glucurone and galacturonic acid.     

Synthesis of sulfonamides and sulfonic esters via reaction of amines and phenols with thiols using H2O2–POCl3 system

Phosphorus oxychloride efficiently promoted the synthesis of sulfonamides and sulfonic esters from thiols with hydrogen peroxide in the presence of Amberlite IRA-400 (OH^?). This method has been applied to a variety of substrates including nucleophilic and sterically hindered amines, and also phenols with excellent yields of sulfonamides and sulfonic esters. In most cases these reactions are highly selective, simple, and clean, affording products in excellent yields and high purity.     

Reaction products and kinetics of the reaction of NO2 with γ-Fe2O3

The reaction of NO(2) with Fe(2)O(3) has relevance for both atmospheric chemistry and catalysis. Most studies have focused on hematite, α-Fe(2)O(3), as it is the thermodynamic stable state of iron oxide; however, other forms of Fe(2)O(3) naturally occur and may have different chemistries. In this study, we have investigated the reaction products and kinetics for NO(2) reacting with γ-Fe(2)O(3) powder using diffuse reflectance infrared Fourier transform spectroscopy and compared the results to those of previous studies of NO(2) reacting with α-Fe(2)O(3). Both α- and γ-Fe(2)O(3) produce surface-bound nitrate at the pressures examined in this study (24-212 mTorr); surface-bound nitrite products are observed at all pressures for γ-Fe(2)O(3) whereas nitrite was only observed on α-Fe(2)O(3) at lower pressures. Surface-bound NO(+) and Fe-NO products are observed on γ-Fe(2)O(3), which have not been observed with α-Fe(2)O(3). The reaction kinetics show a first-order dependence on NO(2) pressure and this is used to support the hypothesis of unimolecular reaction of adsorbed NO(2) with the γ-Fe(2)O(3) surface as the slow step in the reaction mechanism. The difference in product formation between NO(2) reacting with γ-Fe(2)O(3) and previous studies of α-Fe(2)O(3) illustrate the fact that care must be taken in generalizing reactivity of different polymorphs.     

Tetramic acids and indole derivatives from amino acid β-keto esters. Fine-tuning the conditions of the key Cu-catalyzed reaction

1,3,5-Trisubstituted tetramic acids and 2,3-disubstituted indole derivatives were prepared from β-keto esters derived from amino acids by their reaction with iodophenyl-2-trifluoroacetylamine under Cu-catalysis. Both heterocyclic systems were generated from the same starting materials by choice of the appropriate reaction conditions.     

η-Cyclopentadienylpalladium(II) complexes: Synthesis, characterization and use for the vinyl addition polymerization of norbornene and the copolymerization with 5-vinyl-2-norbornene or 5-ethylidene-2-norbornene

Dinuclear complexes of palladium(II), containing two bridging halogen (Cl or Br) ligands, [NⁿBu₄]₂[(X₅C₆)₂Pd(μ-Cl)₂Pd(C₆X₅)₂] and [(X₅C₆)(L)Pd(μ-Y)₂Pd(C₆X₅)(L)] (X = F, Cl; Y = Cl, Br), readily react with cyclopentadienylthallium, C₅H₅Tl, to give the corresponding air stable half-sandwich, pseudo-trigonal η⁵-cyclopentadienylpalladium complexes, [NⁿBu₄][(η⁵-C₅H₅)Pd(C₆X₅)₂] (X = F 1, Cl 2) and (η⁵-C₅H₅)Pd(C₆X₅)(L) (X = F, L = CNBu^t3, PPh₃4, PMe₂Ph 5, PEt₃6, AsPh₃7, SbPh₃8; X = Cl, L = PMe₂Ph 9, PEt₃10), respectively. With tetraphenylcyclopentadienylthallium, C₅Ph₄HTl or pentabenzylcyclopentadienylthallium, C₅Bn₅Tl (Bn = CH₂Ph) the air stable half-sandwich complexes (η⁵-C₅Ph₄H)Pd(C₆F₅)(AsPh₃), 12 and (η⁵-C₅Bn₅)Pd(C₆F₅)(AsPh₃), 13 are synthesized accordingly. The molecular structures were verified by NMR-spectroscopy, X-ray crystallography (7, 12, 13) and electron impact-mass spectrometry (EI-MS). The precatalysts 4 and 7 can be activated with methylalumoxane (MAO) for the homopolymerization of norbornene (NB) and 5-ethylidene-2-norbornene (ENB) and for the copolymerization of NB with 5-vinyl-2-norbornene (VNB) or ENB with activities of more than 10⁶ g_PNB/(mol_Pd·h). The higher activity of 7/MAO over 4/MAO towards NB homopolymerization was reversed when the olefin-substituted VNB or ENB were added. Then, the more strongly bound PPh₃ ligand of 4 (versus AsPh₃ of 7) can compete with the olefin functionality of VNB or ENB and assume a directing role for the insertion of the ring double bond. As a consequence 4/MAO shows almost the same activity in NB and ENB homopolymerization.     

Preparation of both enantiomers of cyclopropane derivatives from the reaction of vinyl selenones with di-(−)-bornyl malonate

The reaction of vinyl selenones with di-(?)-bornyl malonate and sodium hydride occurred with low diastereoselectivity and afforded a mixture of two diastereomeric cyclopropane derivatives in comparable yields. These, however, could be easily separated by chromatography. Removal of the bornyl group afforded highly enantiomerically enriched cyclopropanes. An example of the simple conversions of these cyclopropanes into useful cyclopropane α-amino acids is also illustrated. The syntheses of several vinyl selenides and selenones are also described.     

The reaction of β-dicarbonyl compounds with trifluoromethylsulphenyl chloride. Part I. CF3S-substituted esters,anilides of β-keto acids,and their Schiff bases: Synthesis and stability.

The reactions of the β-keto acid derivatives with trifluoromethylsulphenyl chloride were carried out to give the α-SCF₃ substituted esters, anilides, and their Schiff bases of acetyl- and benzoylacetic acids. Ethyl esters of α-(trifluoromethylthio)acetoacetic and α-(trifluoromethylthio)benzoylacetic acids heated in dimethylsulphoxide/water solution give trifluoromethylthioacetone and ω-(trifluoromethylthio)acetophenone respectively, whereas with potassium hydroxide solution they form trifluoromethylthioacetic acid in a good yield.     

A novel annulation reaction of N-substituted-2-nitrosoanilines with esters of α-isocyano acids. A one-pot,two-step route to 2-benzimidazole-substituted esters of α-amino acids

A BF₃-promoted α-addition of isocyanides to both nitrogen atoms of N-aryl-2-nitrosoanilines leads to stable BF₃-complexes of 3-N-hydroxy-(2-alkylimino)benzimidazole derivatives, which, after reduction with Zn in AcOH produce 1-N-aryl-2-alkylaminobenzimidazoles. This two-step annulation proceeds efficiently in a one-pot protocol with isocyanides derived from esters of α-amino acids. The chirality of the latter remains unaffected in the reaction.     

A study of the color reaction of iron with “TTA”

Summary TTA, or 2-Thenoyltrifluoroacetone, gives with ferric ion, in various concentrations colorations ranging from blood red to light pink. The advantages of this test are that it is simple to perform, that it is applicable in different acid media of fairly high concentrations, and that it is somewhat sensitive in the presence of ions that usually interfere with such tests. The sensitivity (limit of identification) was found to be 0,5 and the limit of concentration 1 : 100000 when a benzene solution of the reagent was reacted with a slightly acid solution of ferric ion on spot paper.

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Zusammenfassung TTA (2-Thenoyltrifluoraceton) gibt mit Ferriionen je nach Konzentration der letzteren eine blutrote bis blaßrosa Färbung. Die Probe ist einfach ausführbar und wird durch die Gegenwart von Säuren bis zu ziemlich hohen Konzentrationen sowie durch die Gegenwart störender Ionen wenig beeinträchtigt. Wenn eine Lösung des Reagens in Benzol zu einer leicht angesäuerten Ferrisalzlösung zugesetzt wird, beträgt die Erfassungsgrenze 0,5 bei einer Grenzkonzentration von 1 : 100000.

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Résumé Le TTA, thénoyl-2 trifluoracétone, donne avec les ions ferriques, suivant leur concentration, une coloration rouge sang à rose pâle. L'essai est simple à effectuer et à peine troublé par la présence des acides jusqu'à des concentrations passablement élevées et par la présence des ions gênants. Quand on ajoute une solution du réactif dans le benzène à une solution peu acide de sel ferrique, on observe une limite de sensibilité de 0,5 pour une limite de dilution de 1 : 100000.