Stereospecific Olefin Synthesis via Lithium Vinylcuprates

The conjugate addition of cis- or trans-1-alkenyl-cuprolithium complexes (R? CH?CH? )₂CuLi · X_n

1 R ? alkyl, X ? ligands such as ether, tetrahydrofuran, (CH₃O)₃P and (n-Bu)₃P. Physical studies to determine the structure of these copper reagents are in progress, see footnote ²⁰ of reference [1].

to α, β-unsaturated carbonyl compounds was found to occur with high retention of double bond geometry, affording isomerically pure cis- or trans-γ, δ-ethylenic carbonyl compounds. The same 1-alkenylcuprates also react stereospecifically with alkyl halides to give isomerically pure cis- or trans-olefins.     

Dissociative photoionization of Al2(Ch3)6 and Al2(Ch3)3Cl3 in the range 40–100 eV

Dissociation processes of the organoaluminum compounds Al₂(CH₃)₆ and Al₂(CH₃)₃Cl₃ have been studied in the range of valence and Al:2p core-level ionization by means of photoelectron–photoion and photoion–photoion coincidence techniques. The double-ionization threshold and the Al:2p core-ionization threshold of Al₂(CH₃)₆ are estimated to be about 30 and 80 eV

1 1 eV = 96.4853 kJ mol^?1.

respectively. The relative yields of the H⁺?Al⁺ and H⁺?CH_m,⁺ (m′ = 0–3) ion pairs are enhanced around the Al:2p core-ionization threshold of Al₂(CH₃)₆. The photoion–photoion coincidence intensities of Al₂(CH₃)₃Cl₃ are negligibly small throughout the energy range studied. The ratio of the relative yield of AlC₂H₆⁺ to that of Al⁺ increases smoothly through the Al:2p core-ionization and/or excitation region of Al₂(CH₃)₃Cl₃. The variation of the fragmentation pattern with photon energy is discussed in conjunction with the relevant electronic states.     

Richtlinien und Bemerkungen der Redaktion und des Verlages für Abfassung von Manuskripten für die Zeitschrift für anorganische und allgemeine Chemie

Reaction of Trimethylsilylethers of Unsaturated Alcohols with Schwartz Reagent – Stabilisation of Cyclic Zirconiumorganic Compounds by the Moiety Cp₂ZrH₂ Besides the normal product of hydrozirconation the reaction of allyltrimethylsilylethers CH₂? CHC(R¹R²)OSi(CH₃)₃ ( I : R¹ = R² = H, VIII : R¹ = R² = CH₃, X : R¹ = H, R² = CH₃) with Cp₂Zr(H)Cl yields, as a result of a hydrogenation of the Si? O bond, trimethylsilane and a series of compounds with a Zr? O bond. Depending on the substitution of the α-C atom either dimeric chelates ( III ) or binuclear complexes of the type Cp₂Zr(Cl)CH₂CH₂C(R¹R²)OZr(Cl)Cp₂ ( IX : R¹ = R² = CH₃; XII : R¹ = H, R² = CH₃) are formed. Starting with X and excess Cp₂Zr(H)Cl the binuclear compound XIII is obtained which may be considered as an adduct of Cp₂ZrH₂ to the unsaturated chelate Compound XVII with a structure analogous to XIII is synthesized by the reaction of IX with Cp₂ZrH₂. The ¹H-NMR spectrum is in accordance with the existence of cis-trans-isomers of this complex.     

Conformational studies by nuclear magnetic resonance—IV: Restricted rotation in vinylogous thioamides

Enamino -thial and -thiones R¹C(S)CH?CHNR (R¹ = H or alkyl; R² = Me or Et) have been shown by NMR spectra to exist in two rotational forms, s-cis and s-trans, the populations of the latter being approximately the same as in the case of the parent oxa analogues. An increase of the order of 2 to 4 Kcal/mole in the heights of C? C and C? N rotation barriers (ΔG*) was found on comparing the title compounds with their oxa analogues. IR spectra failed as a tool to establish the rotational equilibrium. IR absorption bands of the ν_{C? C}, ν_{C? H} (in the NMe₂ group) and γ_HC?CH vibrations have been found, but the ν_C?S band could not be assigned unambiguously. Anomalies concerning the frequency and intensity of the ν_C?C band are discussed.     

Chemie von α-Aminonitrilen. 12. Mitteilung. Sondierungen über thermische Umwandlungen von α-Aminonitrilen

Chemistry of α-Amino Nitriles

1 11. Mitteilung: [1].

. Exploratory Experiments on Thermal Reactions of α-Amino Nitriles The paper extends a previously published report [4] on chemical properties of α-amino nitriles and of members of the C₃H₄N₂ ensemble (Scheme 1) as observed in experiments carried out under non-aqueous conditions. The reactions investigated and the observations made are summarized in some detail in the English footnotes (*) referring to Schemes 1–17 and Fig. 1.     

Thermal decompositions of N-methylpyridinium,quinolinium, isoquinolinium and phenanthridinium salts in a mass spectrometer. Evidence for a specific HI elimination and for an oxidation to amides

The mass spectra of some N-methylpyridinium, quinolinium, isoquinolinium and phenanthridinium salts (R⁺X^?)

1 The salt will be represented by R⁺X^? or RX, R⁺ being the organic moiety, with its associated mass and X- the inorganic anion.

are analyzed (X^? = I^? or ClO₄^?). For X^? = I^?, thermal decomposition gives rise mainly to the superimposed spectra of CH₃I and the free base. Hence, iodide salts cannot be determined specifically by their mass spectra. When an α-methyl group is present, e.g. 2-methylpyridinium methiodide, elimination of HI becomes an important thermal process. For X^? = ClO₄^?, the same pattern is observed, but in addition a generally important peak at [R + 15] is present. This peak is due to the oxidation, mainly α to the nitrogen of the organic moiety by the ClO₄^? ion, giving rise to the corresponding amide. In some cases, chlorination of the organic moiety has been observed as well as double oxidation. The thermal processes for the perchlorate salts are characteristic and are useful in the elucidation of the quaternary structure.     

X-ray photoelectron spectroscopic study of the interaction of supported metal catalysts with NO<Subscript>x</Subscript>

The reactions of the platinum and rhodium model catalysts applied to aluminum oxide with NO_x (10 Torr NO + 10 Torr O₂) were studied by X-ray photoelectron spectroscopy. The reaction conducted at room temperature formed on the surface of the oxide support the NO _3,s ^? nitrate ions characterized by the N1s line at 407.4 eV and O1s line at 533.1 eV and the NO _2,s ^? nitrite ions characterized by the N1s line with a binding energy of 404.7 eV. At the same time, the Pt4f and Rh3d lines of the supported platinum particles are shifted toward higher binding energies by 0.5–1.0 eV and 0.7–1.2 eV, respectively. It is assumed that the binding energies increase due to changes in the chemical state of the platinum metal in which oxygen is dissolved. The reaction of NO_x with Pt/Al₂O₃ at 200°C forms platinum oxide defined by the Pt4f _7/2 line with a binding energy of 72.3 eV.     

The application of chiroptical spectroscopy (circular dichroism) in quantifying binding events in lanthanide directed synthesis of chiral luminescent self-assembly structures

The binding of asymmetrical and optically pure tridentate ligands (L = 1(S) and 1(R)) containing one carboxylic group and 2-naphthyl as an antenna to lanthanide ions (M = La(iii) and Eu(iii)) was studied in CH₃CN, showing the successive formation of M:L, M:L₂ and M:L₃ stoichiometric species in solution. The europium complexes EuL₃ were also synthesised, structurally characterised and their photophysical properties probed in CH₃OH and CH₃CN. The changes in the chiroptical properties of both 1(S) and 1(R) were used (by circular dichroism (CD) spectroscopy) to monitor the formation of these chiral self-assemblies in solution. While circularly polarised luminescence (CPL) showed the formation of Eu(1(S))₃ and Eu(1(R))₃ as enantiomers, with high luminescence dissymmetry factors (g _lum), fitting the CD changes allowed for binding constants to be determined that were comparable to those seen in the analyses of absorbance and luminescence changes.     

Gas‐phase chemistry of dihydromyrcenol with ozone and OH radical: Rate constants and products

A bimolecular rate constant, k_{OH + dihydromyrcenol}, of (38 ± 9) × 10^?12 cm³ molecule^?1 s^?1 was measured using the relative rate technique for the reaction of the hydroxyl radical (OH) with 2,6‐dimethyl‐7‐octen‐2‐ol (dihydromyrcenol,) at 297 ± 3 K and 1 atm total pressure. Additionally, an upper limit of the bimolecular rate constant, k, of approximately 2 × 10^?18 cm³ molecule^?1 s^?1 was determined by monitoring the decrease in ozone (O₃) concentration in an excess of dihydromyrcenol. To more clearly define part of dihydromyrcenol's indoor environment degradation mechanism, the products of the dihydromyrcenol + OH and dihydromyrcenol + O₃ reactions were also investigated. The positively identified dihydromyrcenol/OH and dihydromyrcenol/O₃ reaction products were acetone, 2‐methylpropanal (O?CHCH(CH₃)₂), 2‐methylbutanal (O?CHCH(CH₃)CH₂CH₃), ethanedial (glyoxal, HC(?O)C(?O)H), 2‐oxopropanal (methylglyoxal, CH₃C(?O)C(?O)H). The use of derivatizing agents O‐(2,3,4,5,6‐pentafluorobenzyl)hydroxylamine (PFBHA) and N,O‐bis(trimethylsilyl)trifluoroacetamide (BSTFA) clearly indicated that several other reaction products were formed. The elucidation of these other reaction products was facilitated by mass spectrometry of the derivatized reaction products coupled with plausible dihydromyrcenol/OH and dihydromyrcenol/O₃ reaction mechanisms based on previously published volatile organic compound/OH and volatile organic compound/O₃ gas‐phase reaction mechanisms. © 2006 Wiley Periodicals, Inc. *

1 This article is a US Government work and, as such, is in the public domain of the United States of America

Int J Chem Kinet 38: 451–463, 2006     

Acetoxy derivatives of trans-1,2-disilylethylene and their hydrolysis

Conclusions A method was developed for the synthesis of acetoxy-trans-1,2-disilylethylenes of formula (CH₃COO)_n(CH₃)_2–nRSiCH=CHSi(CH₃)R(OCOCH₃), where R and R=alkyl, and n=0 or 1. The corresponding silanols were obtained by the hydrolysis of the latter.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 6, pp. 1395–1397, June, 1976.     

Rifamycin antibiotics—new compounds and synthetic methods. Part 3: Study of the reaction of 3-formylrifamycin SV with primary amines and ketones

In the third stage of our study concerning the search for new antibacterial rifamycin antibiotics, the reactions of 3-formylrifamycin SV (1) with a range of primary alkylamines and ketones of general structure R₁–CH₂–CO–R₂ (R₁H or alkyl and R₂alkyl or aryl) has been investigated. A new synthetic method for the preparation of a new group of rifamycin derivatives with an α,β-unsaturated imine substituent at C-3 has been developed.These compounds showed a tendency to reversibly isomerise in organic solvents and, in the presence of water, to rapidly hydrolyse. The structures of four isolated microcrystalline compounds 2, 3, 4, 5 and a reaction's mechanism have been proposed on the basis of mass spectrometry results as well as (1D) and (2D) ¹H and ¹³C NMR analysis. The new synthetic route reported herein is a promising pathway to new reactive rifamycins displaying broader capabilities than the plain 3-formylrifamycin SV.     

(Perhalogenmethylthio)heterocyclen. XII. Herstellung von Perfluoroalkylsulfonylharnstoff-Derivaten sowie CCl3−nFnX-substituierten Heterocyclen und deren biologische Wirkung

(Perhalomethylthio)heterocycles XII. Preparation of Perfluoroalkylsulfonylurea Derivatives as well as CCl_3?nF_nX-Substituted Heterocycles and Their Biological Activity

1 XI, Mitt., s.[1]

In the presence of CF₃SO₃H (chlorodifluoromethylthio)thiophene 1 reacts with CClF₂SCl to give the 2,5-disubstituted thiophene 2a which on oxidation with 30% H₂O₂-solution yields the corresponding sulfonyl compound 2b · R¹SO₂NCO adds amines to give R¹SO₂NHC(O)NHR 3a – g . Some biological properties of these compounds were investigated.     

The mass spectra of some α-aminooxy acids

The mass spectrometric behaviour of six simple α-aminooxy acids is described. Comparison is made with the electron-impact-induced fragmentation of the parent α-amino acids. The differences are in accordance with the observed

1 See Ref. 1.

chemical character of the α-aminooxy acids.     

Beiträge zur Chemie der Silicium-Schwefel-Verbindungen. XLIX. Reaktion von Silicium-Schwefel-Verbindungen mit Glykolen

Contribtions to the Chemistry of Silicon-Sulphur Compounds. XLIX. Reaction of Silicon-Sulphur Compounds with Glycols The reactions of Ph₃SiSH, (RO)₃SiSH, (RO)₂Si(SH)₂, cyclo-[(t-BuO)₂SiS]₂, and SiS₂ with aliphatic glycols were investigated. Among other compounds representatives of a new group of silanethiols (t-BuO)₂Si(SH)OrOSi(SH)(OBu-t)₂ (r = pr; neopent)

1 r = kohlenwasserstoffgerüst des Glykols: pr = ? CH₂CH₂CH₂? , bu = ? CH₂(CH₂)₂CH₂? , hex = ? CH₂(CH₂)₄CH₂? , neopent = ? CH₂C(CH₃)₂CH₂? , pin = ? C(CH₃)₂C(CH₃)₂?

were obtained. Informations about the hydrolytic splitting of the Si? S bond of the prepared silanethiols were obtained by thiomercurimetric titration. A pathway of the reaction of SiS ₂ with glycols is discussed.     

Diazaallyls of group 4 metals based on trans-1,2-diaminocyclohexane

Amination of 1-bromo-2-methylpyridine with trans-1,2-diaminocyclohexane gives the corresponding bis(aminopyridine) H₂L¹. Conversion of the same diamine to the N,N′-bis(amino-4,4-dimethylthiazoline) H₂L² is also completed in three steps. The analogous aminooxazoline is however inaccessible, although the aminocyclohexane analogue is prepared readily. The proligand H₂L¹ forms bis(aminopyridinato) alkyl complexes of the type [ZrL¹R₂] (R = CH₂Ph, CH₂Bu^t). The molecular structure of the neopentyl complex shows that the chiral backbone leads to a puckering of the N₄Zr coordination sphere, which contrasts with the related cyclohexyl-bridged Schiff-base complexes which are essentially planar. [ZrL²(CH₂Bu^t)₂] - the first aminothiazolinato complex - is formed similarly. A comparison of the structures of [ZrL¹(CH₂Bu^t)₂] and [ZrL²(CH₂Bu^t)₂] indicates that the latter has a fully delocalised N-C-N system, rather similar to a bis(amidinate). Reaction of H₂L² with [Ti(NMe₂)₄] gives [TiL²(NMe₂)₂] which appears to be C₂-symmetric like the above complexes according to NMR spectra, but has one uncoordinated thiazoline unit in the solid state. This is a result of increased ring strain at the smaller titanium metal centre.     

Exploring the unique reactivities of heterobicyclic tetrazoles—access to functionally diverse and versatile heterocyclic scaffolds

The benzylic hydrogen atom in oxabicyclic tetrazoles such as (6R,8R)-(8-phenyl-5,6-dihydro-8H-tetrazolo[5,1-c][1,4]oxazin-6-yl)-alkanols (A, X=CH₂OH) is highly acidic, being alkylated in preference to a hydroxymethyl group with NaH and active alkyl halides. The enantioenriched products B now contain a phenyl and alkyl group on a stereogenic benzylic carbon atom. The products are subject to β-elimination to give 1-{1-[3-propenyl]-1H-tetrazol-5-yl}-1-phenyl-alkanols. Cleavage of the propenyl chain leads to chiral non-racemic 1-phenyl-1-(1H-tetrazol-5-yl)-alkanols C. Free-radical ‘anomeric’ azidation of the oxabicyclic tetrazoles followed by reduction and ring closure with inversion of configuration produces azabicyclic tetrazoles D as constrained functionalized piperazines.     

Synthesis and structures of new 1,3,6,2-dioxazaborocanes containing substituents in the ocane fragment

New 1,3,6,2-dioxazaborocanes R¹N(CHR³CR⁴R²O)(CHR⁶CHR⁵O)BX (1–11, X = Ph, 4-MeC₆H₄, Me; R¹ = Me, PhCH₂; R², R³, R⁴, R⁵, R⁶ = H, Ph) were synthesized by the reactions of aryl- or methylboronic acids with dialkanolamines. The treatment of (Me₂NCH₂CH₂O)₃B (15) with MeN(CH₂CH₂OH)(CH₂CPh₂OH) afforded 2-[2-(dime-thylamino)ethoxy]-1,3,6,2-dioxazaborocane (12). 2-Fluoro-1,3,6,2-dioxazaborocanes R¹N(CHR³CHR²O)(CH₂CH₂O)BF (13: R¹ = PhCH₂, R² = R³ = H; 14: R¹ = Me, R² = R³ = Ph, threo) were synthesized by the reaction of bis(trimethylsilyl) ethers of the corresponding dialkanolamines with BF₃·Et₂O. The new borocanes can be used for the synthesis of the corre-sponding germanium derivatives PhCH₂N(CH₂CH₂O)₂GeX₂ (16, X = OEt; 17, X = Cl), as exemplified by the reaction of compound 6. The structures of erythro-MeN(CH₂CH₂O)(CHPhCHPhO)BPh (3), threo-MeN(CH₂CH₂O)(CHPhCHPhO)BPh (4), erythro-MeN(CH₂CH₂O)(CHPhCHPhO)B(4-MeC₆H₄) (8), and PhCH₂N(CH₂CH₂O)₂BF (13) were established by X-ray diffraction. The coordination polyhedra of the boron atoms in these complexes can be described as distorted tetrahedra. The boron-nitrogen distances (1.705(7)–1.723(3) Å) provide unambiguous evidence for the presence of the B←N transannular interaction in these compounds. The structures of the resulting borocanes containing phenyl substituents at the carbon atoms of the ocane skeleton were studied by NMR spectroscopy and quantum chemical density functional theory calculations.     

Glow discharge polymerization of tetramethylgermanium

A glow discharge polymerization technique was applied in the preparation of germanium-containing polymers. The colorless and transparent polymer films formed from tetramethylgermanium (TMG) were investigated by elemental analysis, infrared (IR) spectroscopy, and ESCA. The reaction of TMG was accompanied by the rupture of bonds between Ge and CH₃ groups which led to mixtures of polymers that consisted of CH₃, CH₂, Ge? CH₃, Ge? O? C, and Ge? O? Ge groups and germanium metal. Most Ge species present at the outermost layers of the films were oxidized subsequently by air, whereas the Ge species at the inner layers still existed as Ge metal. This film-forming process can be explained by the concept of atomic polymerization proposed by Yasuda.

1 See H. Yasuda, J. Polym. Sci. Macromol. Rev., 16 , 199 (1981).