Etudes sur les composés organométalliques. X [1]. Action d'organomagnésiens sur la benzophénone

Various Grignard reagents and their diorganomagnesium complexes with ether or pyridine have been reacted with benzophenone, using different mole ratios and orders of addition. Analysis of the reaction products has provided information as to probable reaction mechanisms of addition and reduction. A monomeric diorganomagnesium reagent, favoured either by addition of the reagent to the ketone or by complexation of the reagent with pyridine, enhances if possible the reduction reaction.     

Etudes sur les composés organométalliques. XI [1]. Action du tétrabutoxytitane sur des solutions de Grignard

The reaction of titanium tetra-n-butoxide with phenylmagnesium bromide inether has been investigated. The species (C₆H₅)₂Mg in the Grignard reagent leads to (C₆H₅)₄Ti, whereas the dimeric species (C₆H₅)₂Mg · MgBr₂ produces an insoluble complex mTi(OBu)₄ · n[(C₆H₅)₂Mg · MgBr₂]. Applied to other Grignard reagents, the use of R₂Mg allowed the preparation of tetrabenzyltitanium, tetracyclohexyltitanium and tetramethyltitanium. Cristalline (C₆H₅)₄Ti and (C₆H₅CH₂)₄ Ti have been isolated.     

Effets stériques des groupes alkyle sur le déplacement chimique des hydrogènes d'un méthyle: Correlation avec les termes Es de Taft

The effect of alkyl groups (Me, Et, i-Pr, t-Bu) on the ortho methyl proton chemical shifts is shown to be linearly correlated with the Taft (E_s) scale in model compounds 1 . Experimental results can be expressed by Δδ = δ_R – δ_Me = λ′E_s in which λ′ is solvent and model dependent. The calculations of the chemical shifts according to ApSimon and Buckingham are used to show the predominant influence of steric effects on the observed substituent effect.     

Etude sur les composés organométalliques III [1]. Action d'organomagnésiens sur des complexes du tétrachlorure de titane

The reaction between RM_gX and TiCl₄,2L (L = pyridine, piperidine or quinoleine) is shown to give a high yield of organo-titanium (IV) compounds. As expected, the decomposition of the latter is reduced to a minimum by the ligand L initially present, allowing the preparation of etheral solutions of R₄Ti (R = benzyl, phenyl or butyl). R₄Ti is obtained whatever may be the initial molar ratio of RM_gX/TiCl₄, 2L.     

Etudes sur les composés organométalliques,XIII [1] Action d'organomagnésiens sur la benzalacétone

The reactions of benzalacetone with n-BuMgBr and PhMgBr have been compared with the corresponding reactions with the diorganomagnesium complexes of ether and pyridine. The results obtained by using different mole ratios of reactants and orders of addition show that the conjugated addition reaction is enhanced if a monomeric diorganomagnesium reagent is available; this condition can be realized either by adding a diorganomagnesium complex to the ketone or by complexing the diorganomagnesium with pyridine. Probable reaction mechanisms for normal and conjugated addition reactions are suggested.     

Thiazoles polycycliques. I. Substitution par les nucléophiles anioniques des dérivés 2-méthylsulfonylés de la thiazolo[5,4-b]-pyridine et du benzothiazole

Substitution reactions of 2-methylsulfonyl thiazolo[5,4-b]-pyridine (3) and 2-methylsulfonyl benzothiazole (10) by nucleophilic anionic reagents were studied. In N,N-dimethylformamide, at 20°, these reactions are fast, particularly with compound 3 . Also studied were the kinetics of the substitution by sodium methylate, and the pK_a′s of the acidic compounds. This work allows the comparison of benzothiazole with its “7-aza” analog.     

Beiträge zur Chemie des Phosphors. 159. Über die Reaktion des Diphosphaborirans (t-BuP)2BN(i-Pr)2 mit Kalium bzw. Kaliumnaphthalid

Contributions to the Chemistry of Phosphorus. 159. On the Reaction of the Diphosphaborirane (t-BuP)₂BN(i-Pr)₂ with Potassium or Potassium Naphthalenide The reaction of (t-BuP)₂BN(i-Pr)₂ with potassium or K-naphthalenide in tetrahydrofuran leads to K(t-Bu)P? ;BN(i-Pr)₂? P(t-Bu)K ( 1 ) via P? ;P bond cleavage of the three-membered ring skeleton. Above ? 78°C 1 changes into the asymmetric compound K(t-Bu)P? ;P(t-Bu)? BHN(i-Pr)₂ ( 2 ). In dimethoxyethane additionally the monometallated diphosphaborirane K(t-Bu)P₂BN(i-Pr)₂ ( 3 ) is formed. 1 and 3 , which could be isolated free from other phosphorus containing compounds, as well as the corresponding silylphosphanes Me₃Si(t-Bu)P? ;BN(i-Pr)₂? ;P(t-Bu)SiMe ₃ ( 4 ) and Me₃Si(t-Bu)P₂BN(i-Pr)₂ ( 5 ) were characterized by NMR spectroscopy. Protolysis of 3 or 5 leads to a decomposition of the three-membered ring skeleton with formation of H(t-Bu)P? ;PH₂.     

Homoleptische Zinkamide: Der Übergang zu monomeren Molekülen

Homoleptic Zinc Amides: Transition to Monomeric Molecules Zinc chloride reacts with the lithium salts of the bulky secondary amines HN(i-Bu)₂ and HN(t-Bu)₂ to form the corresponding homoleptic zinc compounds {Zn[N(i-Bu)₂]₂}₂ ( 1 ) and Zn[N(t-Bu)₂]₂ ( 2 ). The NMR spectroscopic and mass spectrometric results as well as the molecular weight determinations and X-ray diffraction data are consistent with a dimeric structure of 1 and a monomeric structure of 2 in the gas phase, in solution and in the solid state.     

Etudes sur les composés organométalliques I action du chlorure de benzylmagnésium et du bromure de phénylmagnésium sur le tétrachlorure de titane

The reactions between phenylmagnesium bromide or benzylmagnesium chloride and titanium tetrachloride have been studied. The influence of the introduction order of the reagents is mentioned. Decomposition of the (non-isolated) compounds R_nTiX_4-n is shown to be essentially intermolecular, and rarely intramolecular.     

Influence d'une fonction ester ou acide portée par la chaîne alcoxyle sur la réactivité des sels de N-alcoxypyridinium envers les ions cyanures

Study of the reactivity towards cyanide ions, of N-alkoxy-pyridinium salts bearing an ester group in the α-position of their alkoxy chain, shows that a decomposition to pyridine and α-carbonyl ester competes with cyanopyridine formation. This competitive decomposition can become predominant as the acidity of the α-hydrogen is increased. In spite of its steric crowding, which brings an increase in the 4-cyanopyridine ratio, the salt 3 , which presents a tertiary α-carbon, reacts normally. Salts carrying an -α or -β acid group show a very reduced reactivity due to an unfavourable pH diminution and to the formation of a betaine which is less reactive than alkoxy-pyridinium ion. A folded conformation of this betaine would explain a relatively enhanced reactivity of the 4-position as compared to the reactivity of the 2-position of the pyridine ring.     

Oligomérisation anionique de l'ethylène. I. Etude cinétique

A kinetic study of ethylene oligomerization in hexane, in the presence of n-BuLi–TMEDA complexes, allowed us to suggest a new mechanism for anionic ethylene oligomerization. n-BuLi and n-Bu(CH₂CH₂)Li species have the same reactivity. The RLi–TMEDA complex in a 1-to-1 stoichiometry is the active species. The following kinetic equation has been established: It reflects the intervention of associated species (n-BuLi–TMEDA)₂ as well as the influence of the concentration of the complexing agent on the kinetics of oligomerization.     

Sur les orthoamino formyl quinoléines,nouveaux synthons hétérocycliques

The four o-aminoformylquinolines substituted on the pyridine ring were synthesized from the corresponding aminoquinoline-carboxylic acids. This convenient method was to used to prepare the four isomers and among them the 2-formyl-3-aminoquinoline which is not very stable. These new compounds provide new nitrogen-containing heterocyles having potential pharmaceutical properties.     

A Comparative Study of Platinum Di (t-butyl) (15N2)diimine and trans-[(PtCl2(N-ligand)PBu3)] complexes by 195Pt-, 31P- and 15N-NMR

¹⁹⁵Pt-, ³¹P- and ¹⁵N-NMR. data are presented for [PtCl₂ (t-Bu ¹⁵N?CH? CH?¹⁵N (t-Bu)) (η²-styrene)] ( 1 ), trans-[{PtCl₂ (PBu₃)}₂ (t-Bu ¹⁵N?CH? CH?¹⁵N (t-Bu))] ( 2 ), trans-[PtCl₂ (t-Bu ¹⁵N?CH? CH?¹⁵N (t-Bu)) (PBu₃)] ( 3 ) and various complexes of the type trans-[PtCl₂ (N-ligand) (PBu₃)]. In solution the gross structural features of 1 and 2 are shown to be in agreement with those found in the solid state; namely, 1 contains five-coordinate Pt and 2 is dinuclear. In 3 Pt is four-coordinate with only one N-atom of the diimine ligand being coordinated at ?50° in CD₂Cl₂. The NMR. data for 2 and 3 are compared with those of trans-[PtCl₂ (N-ligand) (PBu₃)] (N-ligand = pyridine, 2, 6-dimethylpyridine, (¹⁵N)-hexylamine, (¹⁵N)-t-butylamine and (¹⁵N)-aniline) and are discussed in terms of the donor and acceptor properties of the N-ligands.     

Synthesis of 2,3‐Diaryl‐3H‐pyrrolo[2,3‐c]pyridin‐3‐ol Derivatives by the Reaction of Aryl(3‐isocyanopyridin‐4‐yl)methanones with Aryl Grignard Reagents

The reaction of aryl(3‐isocyanopyridin‐4‐yl)methanones 1 , easily prepared from commercially available pyridin‐3‐amine, with aryl Grignard reagents gave, after aqueous workup, 2,3‐diaryl‐3H‐pyrrolo[2,3‐c]pyridin‐3‐ols 2 . These rather unstable alcohols were O‐acylated with Ac₂O in pyridine in the presence of a catalytic amount of 4‐(dimethylamino)pyridine (DMAP) to afford the corresponding 2,3‐diaryl‐3H‐pyrrolo[2,3‐c]pyridin‐3‐yl acetates 3 in relatively good yields.     

Beiträge zur Chemie des Phosphors. 138. P5(t-Bu)4H – das erste Derivat von iso-P5H5

Contributions to the Chemistry of Phosphorus. 138. P₅(t-Bu)₄H — the First Derivative of iso-P₅H₅ The thermolysis of 1,2-di-tert-butyldiphosphane, H(t-Bu)P? P(t-Bu)H, yields under suitable conditions the compound P₅(t-Bu)₄H ( 1 ) as the main product. Besides, the tert-butylphosphanes t-BuPH₂, P₆(t-Bu)₅H ( 2 ), H₂(t-BuP)₃, and (t-BuP)₄ are formed. 1 has been isolated in the pure state and structurally characterized as 1-(tert-butylphosphino)-2,3,4-tri-tert-butyl-cyclotetraphosphane. Hence, compound 1 is a derivative of iso-P₅H₅ with a branched phosphorus skeleton built up by a four-membered ring and a phosphorus side chain.     

Beiträge zur Chemie des Phosphors. 224. Zur Thermolyse von 1,2-Di-tert-butyldiphosphan, 1,2,3-Tri-tert-butyltriphosphan und Tetra-tert-butylcyclotetraphosphan

Contributions to the Chemistry of Phosphorus. 224. On the Thermolysis of 1,2-Di-tert-butyldiphosphane, 1,2,3-Tri-tert-butyltriphosphane, and Tetra-tert-butylcyclotetraphosphane On disproportionation of 1,2-di-tert-butyldiphosphane, H(t-Bu)P? P(t-Bu)H (1) , 1,2,3-tri-tert-butyltriphosphane, H₂(t-BuP)₃ (2) , is formed which reacts further at temperatures above 100°C to give 1-(tert-butylphosphino)-2,3,4-tri-tert-butylcyclotetraphosphan, P₅(t-Bu)₄H (4) . Compound 4 reacts with 1 or 2 with lengthening of the P-sidechain to furnish the corresponding 1-(1,2-di-tert-butyldiphosphino)-2,3,4-tri-tert-butylcyclotetraphosphane, P₆(t-Bu)₅H (5) . At temperatures above 170°C, 5 disproportionates into the tetra-tert-butylcyclotetraphosphane, (t-BuP)₄ (3) which is stable up to about 200°C, and the bicyclo[3.1.0]hexaphosphane P₆(t-Bu)₄ from which the polycyclophosphanes P₉(t-Bu)₃ and P₈(t-Bu)₆ arise during the further course of the thermolysis. These products are finally converted through even more phosphorus-rich and more highly condensed t-butylcyclophosphanes into elemental phosphorus. In each reaction step, varying amounts of the monophosphane derivatives t-BuPH₂, (t-Bu)₂PH, and (t-Bu)₃P are formed. The proposed course of the reaction is further substantiated by the pyrolysis products of pure 2 and 3 .     

Déplacements chimiques induits en RMN par un réactif lanthanidique: I—Application á l'analyse conformationnelle de sulfites cycliques

The chemical shifts induced by Eu(fod)₃ in several series of 6-membered cyclic sulfites give the parameters K_c and Δ_SR of the complexation equilibrium for an assumed 1:1 stoicheiometry. The equilibrium constant K_c decreases with increasing bulk of the C-4 and C-6 substituents and polarity of the C-5 substituent, which corresponds to the increase of the i.r. stretching frequency vS?O. Thus axial S?O will be more tightly complexed than equatorial S?O. It can be predicted that when a conformational equilibrium exists without shift reagent, displacement towards an axial S?O form will occur with the reagent. Use of the Δ_SR pseudocontact equation confirms the following: (i) ax S?O chair forms are stabilized; (ii) eq S?O chairs with two eq C-4 and C-6 substituents show an equilibrium with a few percent of the ax S?O flexible conformation, particularly in the absence of an ax C-5 substituent; (iii) twist forms with a 2–5 axis, intermediate S?O and trans-4, 6-di-tert-Bu substituents give a boat form with O at the prow and ax S?O; (iv) the conformational equilibrium of trans-5-tert-butyl-2-oxo-1, 3, 2-dioxathiane (chair with ax tert-Bu and S?O ? 70%) is completely displaced towards that form; (v) cis-4,4,6-trimethyl-2-oxo-1,3,2-dioxathiane, which exists as an equilibrium in which the three types of S?O occur, is complexed essentially in the twist form with a 1–4 axis and ax S?O. Most of these results are supported by the coupling constants analysis for the ratio R₀/S₀ = 1.     

Beiträge zur Chemie des Phosphors. 142. P6(t-Bu)5H – das erste Cyclotetraphosphan mit P2-Seitenkette

Contributions to the Chemistry of Phosphorus. 142. P₆(t-Bu)₅H – the First Cyclotetraphosphane with a P₂ Side Chain The thermolysis of 1, 2-di-tert-butyldiphosphane, H(t-Bu)P? P(t-Bu)H, leads to formation of the hitherto unknown hexaphosphane P₆(t-Bu)₅H ( 1 ). In the first instance the iso-P₅H₅ derivative P₅(t-Bu)₄H [3] is formed, which reacts further with H₂(t-BuP)₂ or H₂(t-BuP)₃ yielding 1 . Compound 1 has been isolated in the pure state and structurally characterized as 1-(1,2-di-tert-butyldiphosphino)-2, 3, 4-tri-tert-butyl-cyclotetraphosphane, i. e. as a four-membered ring compound with a P₂ side chain. Due to the chirality of the P atoms in the side chain, 1 exists as a mixture of two configurational isomers, the threo-and the erythro-form.     

I. Etude de l'Influence de la Nature et de l'Orientation d'un Substituant sur les Constantes de Couplage en Série Tertiobutyl-4 Cyclohexanonique par RMN à Haut Champ

The 250 MHz proton spectra of six α-halogeno-4-tert-butylcyclohexanones have been recorded and the dependence of the coupling constants upon the nature, the position, the orientation and the number of substituents (C?O, Cl, t-Bu) has been examined. The results obtained are interpreted in terms of geometrical deformation or substituent effects.     

Reactive fiber. V. Preparation and polymerization of p-styrenesulfonyl (β-chloroethyl)amide

p-Styrenesulfonyl(β-chloroethyl)amide (III) was prepared and copolymerized with styrene (M₁). The monomer reactivity ratios were determined (r₁ = 0.25 = 0.1, r₂ = 1.25 ± 0.25), and Q and e values were calculated (1.69 and 0.28, respectively). The polymer reacts with nucleophilic reagents such as amines and phenols in the presence of pyridine to the extent of 15–98%. Fibers from copolymers of acrylonitrile and III react with Congo Red in the presence of pyridine.