bluuebunny/crossref_metadata_2025_split huggingface dataset:
Funktionalisierung von C60 mit Nitriloxiden zu 4,5‐Dihydroisoxazolen und deren Strukturbestimmung
Authors: Irngartinger Hermann , Köhler Claus‐Markus , Huber‐Patz Ursula , Krätschmer Wolfgang 
Published: July 2007

Functionalization of C60 with Nitrile Oxides to 4,5‐Dihydroisoxazoles and Their Structure DeterminationCycloadducts 3 of nitrile oxides 2 with C60 (1) are synthesized and isolated. The cycloadducts are characterized by 13C‐NMR spectroscopy and high‐resolution FAB mass spectrometry. X‐ray structure determination of the 3‐(9‐anthryl)‐4,5‐dihydroisoxazole derivative 3a of C60 with CS2 included in the crystals is achieved at 173 K without disorder problems.
Bis[2,3‐naphthalenediolato(2 — )](pyrrolidiniomethyl)germanate—Tetartoacetonitrile, the First Zwitterionic λ5‐Germanate: Synthesis and Crystal Structure Analysis
Authors: Tacke Reinhold , Sperlich Jörg , Becker Beate 
Published: July 2007

AbstractThe zwitterionic spirocyclic λ5‐germanate bis[2,3‐naphthalenediolato(2—)](pyrrolidiniomethyl)germanate (8) was synthesized and the crystal structure of its tetartoacetonitrile solvate 8 · 1/4 CH3CN studied by single‐crystal X‐ray diffraction. Compound 8 was prepared by reaction of (MeO)3‐GeCH2NC4H8 (11; NC4H8 = pyrrolidino) with two equivalents of 2,3‐naphthalenediol (isolated as 8 · 1/4 CH3CN; yield 92%). The coordination polyhedron around the pentacoordinate germanium atom of 8 · 1/4 CH3CN can be described as a strongly distorted trigonal bipyramid (the structure is displaced by 38.9% from the ideal trigonal bipyramid towards the ideal square pyramid), the carbon atom occupying an equatorial position. In the crystal lattice of 8 · 1/4 CH3CN, the zwitterions form intermolecular NH ⃛O hydrogen bonds leading to the formation of dimers. 1H‐ and 13CNMR studies revealed that 8 also exists in solution ([D6]DMSO).
Enantioselective Oxidation of Chiral Titanium Enolates Derived from Propiophenone by Dimethyldioxirane or 3‐Phenyl‐2‐phenylsulfonyloxazirdine
Authors: Adam Waldemar , Prechtl Frank 
Published: July 2007

AbstractThe stereoselective oxidation of the optically active titanium enolate complexes 2 of propiophenone by dimethyldioxirane (3) (as acetone solution) and 3‐Phenyl‐2‐phenylsulfonyloxaziridine (4) has been investigated. The chiral titanium enolates 2 were synthesized by the reaction of the lithium enolate of propiophenone and the respective optically active chlorotitanate complexes 1. For 3 as oxidant, the stereoselectivity of the α hydroxylation strongly depends on the substitution pattern at the central titanium atom and reached for the best case, namely 2e, an enantiomeric excess (ee) of 63%. Solvent and temperature exhibited only small effects on the stereoselectivity. Compound 4 as oxidant gave lower enantiomeric excesses than 3.
Thermally Initiated Free‐Radical Chain Addition of Alkanes to Alkynes, II. Kinetics of the Addition of Cyclohexane to Phenylethyne under Supercritical Fluid Conditions
Authors: Metzger Jürgen O. , Bangert Fritz 
Published: July 2007

AbstractThe kinetics of the addition of cyclohexane (2) to phenylethyne (1) proceeding via 2‐cyclohexyl‐1‐phenylethenyl radical (3) to give 1‐cyclohexyl‐2‐phenylethene (4) was investigated in the temperature range from 260 to 340°C. The radical chain is initiated by a bimolecular reaction of cyclohexane with phenylethyne to give a cyclohexyl radical and a 1‐phenylethenyl radical. The physical state of the reaction mixture was varied from liquid to supercritical and to gasphase conditions. No effect on the reaction rate constant near the critical point was observed.
Bimolekulare Radikalbildung durch H‐Transfer, 7. Katalyse der Transferhydrierung von α‐Methylstyrol durch 9,10‐Dihydroanthracen mit 7H‐Benz[de]anthracen
Authors: Gerst Matthias , Morgenthaler Jens , Rüchardt Christoph 
Published: July 2007

Bimolecular Formation of Radicals by H‐Transfer, 7[1]. — Bimolecular Formation of Radicals via H‐Transfer with Catalysis by 7H‐Benz[de]anthraceneThe transfer hydrogenation of α‐methylstyrene (2) by 9,10‐dihydroanthracene (1) (DHA) with 7H‐benz[de]anthracene (8) as a catalyst proceeds already at 210–260°C. Isotopic labeling, ESR spectroscopy, radical clock experiments, solvents effects, and thermochemical calculations support the postulated stepwise radical mechanism induced by bimolecular formation of radicals.
Transition Metal‐Catalyzed Annulation Reactions, VII. Palladium‐Catalyzed CH Activation at Methoxy Groups: Regiochemistry of the Domino Coupling Process
Authors: Dyker Gerald 
Published: July 2007

AbstractBy palladium catalysis substitutedortho‐iodoanisoles (5, 8, 10, 13) are transformed either to annulated pyran (6) or furan derivatives (7, 9, 11, 14, 15), depending on the reactivity of additional substituents. The regiochemistry of the domino coupling processes is analyzed and a mechanistic rationale developed. Key step is the CH activation at methoxy groups.
Gürtelförmige Moleküle mittels repetitiver Synthesestrategie
Authors: Josten Wolfgang , Karbach Detlef , Nieger Martin , Vögtle Fritz , Hägele Klaus , Svoboda Michael , Przybylski Michael 
Published: July 2007

Belt‐Shaped Molecules by a Repetitive Synthetic StrategyBelt‐shaped molecules of the general type 2 containing up to five benzene ring units (cf. 37) have been synthesized by macrocyclisation reactions of ribbon‐shaped precursors. An intermolecular cyclization step generates the macroheterocycles 38 and 40. The fourfold‐bridged cyclophane 36 are prepared by intra‐and intermolecular cyclization reactions. The X‐ray structure analyses of 14, 16, 22, 23, 28, and 36 show S‐shaped conformations of the molecules.
Distinction of Fe+NCH and Fe+CNH Complexes by Gas‐Phase Ion‐Molecule Reactions
Authors: Stöckigt Detlef , Schwarz Helmut 
Published: July 2007

AbstractThe bond dissociation energies and the heats of formation of the complexes Fe+NCH (6) and Fe+CNH (10) have been determined. The HCN ligand in 6 is by 3 kcal/mol less strongly bound to Fe+ than HNC in 10, and complex 6 is 13 kcal/mol more stable than 10. Isomerization of 10 to 6 is difficult if not impossible to bring about as, upon collisional activation, mutual isomerization cannot compete with ligand detachment. In addition, the ion‐molecule reactions of 6 and 10 with O2 give rise to distinct product distributions.
Pentamethylcyclopentadienyl‐substituiertes Selenadiphosphiran und Selenatriphosphetan: Synthese, Struktur, Dynamik und einige Reaktionen
Authors: Jutzi Peter , Brusdeilins Norbert , Stammler Hans‐Georg , Neumann Beate 
Published: July 2007

Pentamethylcyclopentadienyl‐Substituted Selenadiphosphirane and Selenatriphosphetane: Synthesis, Structure, Dynamic, and Some ReactionsHerrn Prof. R. Schmutzler zum 60. Geburtstag gewidmet.
1,2,3‐Tris(pentamethylcyclopentadienyl)cyclotriphosphane (1) reacts with selenium to form the insertion product 2,3,4‐tris(pentamethylcyclopentadienyl)selenatriphosphetane (2), which is trapped as the selenium‐coordinated pentacarbonylchromium complex 4. Compound 4 is the first isolated selenatriphosphetane complex. Reaction of 2 with selenium yields 2,3‐bis(pentamethylcyclopentadienyl)selenadiphosphirane (3). 3 replaces thf of Cr(CO)5thf to give the chromium complex 5. The reaction of 3 with K[Fe(CO)2Cp*] leads to the substitution product 6 and the bicyclic phosphane 7. The X‐ray structures of 3 and 4 are presented. The dynamic behavior of 3–6 is discussed.
Evidenz für eine Struktur‐Reaktivität‐Beziehung bei sperrig substituierten Lithium(fluorsilyl)phosphaniden
Authors: Drieß Matthias , Winkler Uwe , Imhof Wolfgang , Zsolnai Laszlo , Huttner Gottfried 
Published: July 2007

Evidence for a Structure‐Reactivity Relationship of Crowded Substituted Lithium (Fluorosilyl)phosphanidesThe molecular structures and the reactivity of the new solvated lithium (fluorosilyl)phosphanides 1a, 2a, and 2b has been investigated. The unusual solid state structures of 1a and 2b are established by X‐ray crystallography. Whereas the lithium centre in 1a is bound to phosphorus and solvated by three molecules of THF, the electronical saturation of the lithium centre in 2b is achieved by a LiP bond, tridentate chelatization (fluorine, phosphorus, nitrogen), and the additional coordination of one molecule of THF. The trigonal‐planar geometry at phosphorus in 1a is unprecedented for derivatives of this type and reflects the steric demand around the phosphorus and the possibility of πp/σ*sic hyperconjugation. The SiP bond lengths [PSiC(Phenyl) 2.186(2) and PSiF 2.164(2) Å] are significantly shorter than in related pyramidally configurated derivatives (1b, c: PSiC 2.21, PSiF 2.18 Å). Both phosphorus atoms in 2b are pyramidally coordinated, but the intramolecular chelate coordination of the lithium centre causes much smaller bonding angles at the SiP phosphorus atom [sum of bonding angles 238.4(2) (PSi), 312.5(1)° (PN)]. 1a as well as 2a, b show quite different reactivity as compared to 1b–d due to their unusual structures. Heating of solutions of 1a and 2a, b in toluene or hexane does not give the expected stable silylidenephosphanes (SiP) by elimination of LiF. Instead, rearrangement reactions of the SiP intermediates 6, 8 lead to the new heterocycles 5, 9. A single‐crystal X‐ray diffraction analysis of 5 has been performed. The Si2P2 cyclobutane ring is planar, and the NMe2 groups at the ring silicon atoms are cis‐orientated. — Interestingly, 2b eliminates LiNiPr2 at 20°C in a kinetically controlled process to form the tetraphosphacyclobutane 7 as the major product. Presumably, the diphosphene 8 is an intermediate in this reaction.
Thianthrene 5‐Oxide (SSO) as a Mechanistic Probe of the Electrophilic Character in the Oxygen Transfer by Dioxiranes
Authors: Adam Waldemar , Golsch Dieter 
Published: July 2007

AbstractThianthrene 5‐oxide (SSO) is established as a useful and convenient chemical probe to assess the electronic character (Xso) of oxygen transfer agents. Thus, H2O2 under basic conditions (HOOH/nBu4NOH) gives an Xso value of 1.00, while H2O2 under acidic conditions (HOOH/HClO4) affords an Xso value near zero. On this Xso scale, dimethyldioxirane (Xso = 0.13 at 0°C) and methyl(trifluoromethyl)dioxirane (Xso = 0.10 at 0°C) are, as expected, definitely strong electrophilic oxidants.
Preparation of 2H‐Benzoxetes by Photoinduced [2 + 2] Cycloaddition of Quinone Methides, Accessible by Dimethyldioxirane (DMD) Oxidation of 2,3‐Dimethylbenzofurans
Authors: Adam Waldemar , Sauter Markus , Zünkler Corinna 
Published: July 2007

AbstractIrradiation (λ > 366 nm) of the quinone methides 3, which were formed by valence isomerization of the methyl‐, chloro‐, and tert‐butyl‐substituted 2,3‐dimethylbenzofuran epoxides 2, afforded the novel 2H‐benzoxetes 4 by photochemical [2 + 2] cycloaddition. These strained and highly labile benzoxetes 4 were spectrally (1H and 13C NMR) characterized at subambient temperatures. On prolonged storage (2–3 d) at –20 to –10°C, the benzoxetes 4 reverted to the quinone methides 3 and/or benzofuran epoxides 2.
Tin for Organic Synthesis, 11. A Mild and Effective Synthesis of α,β‐unsaturated Carboxamides and Sulfonamides by Electrophilic Substitution of Alkenylstannanes with Isocyanates
Authors: Niestroj Michael , Neumann Wilhelm P. , Thies Olaf 
Published: July 2007

AbstractA new and effective method for the preparation of a variety of olefinic carboxamides 6a–k and N‐(4‐methylphenyl‐sulfonyl) carboxamides 7a–d is described. The reaction of aryl and alkyl isocyanates 4a–c or 4‐methylphenylsulfonyl isocyanate 5 with 1‐alkenyltrialkylstannanes 1a–e and di‐1‐alkenyldibutylstannanes 2a–c in the presence of aluminium trichloride provides the corresponding N‐aryl‐substituted olefinic carboxamides 6a–k or the N‐(4‐methylphenyl‐sulfonyl)‐substituted olefinic carboxamides 7a–d in good yields. The stannyl moiety is superior to hydrogen as a leaving group and enables electrophilic ipso substitution at the vinylic system. In the case of di‐1‐alkenyldibutylstannanes the substitutions are also stereospecific, whereas the reactions of 1‐alkenyltrialkylstannanes with isocyanates proceed with partial isomerisation.
Cycloallene, 9. 1‐Phenyl‐1‐aza‐3,4‐cyclohexadien, das erste Isodihydropyridin: Erzeugung und Abfangreaktionen
Authors: Christl Manfred , Braun Martin , Wolz Erich , Wagner Willi 
Published: July 2007

Cycloallenes, 9. — 1‐Phenyl‐1‐aza‐3,4‐cyclohexadiene, the First Isodihydropyridine: Generation and InterceptionThe generation of the title cycloallene 4 from 6,6‐dibromo‐3‐phenyl‐3‐azabicyclo[3.1.0]hexane (10) with methyllithium according to the Doering‐Moore‐Skattebøl method is reported. In the presence of styrene, 1,3‐butadiene, furan, 1,3‐cyclohexadiene, and 1,3‐cyclopentadiene, 4 is intercepted in [2 + 2] and [4 + 2] cycloadditions with formation of the hexahydrocyclobuta[c]pyridines 6 and 11 and the hexahydroisoquinolines 12–15, respectively. The starting compound 10 is prepared via the cis‐disubstituted 1,1‐dibromocyclopropanes 8 and 9 from the known dioxepine derivative 7, the synthesis of which has been considerably improved. On treatment with n‐butyllithium, the dichlorophenylazabicyclohexane 3 is converted into 4 as well. However, in the competition for 4, styrene is not successful against n‐butyllithium, which transforms 4 into the pentadienylamine 5.
A Convenient Synthesis of New Macrocyclic Naphthalenophanes
Authors: Grützmacher Hans‐Friedrich , Nolte Gerald 
Published: July 2007

AbstractThe (1,4)naphthalenophanes 6a, 6b, 7a, and 7b were synthesized regiospecifically in two steps from the appropriate α,β‐di‐1‐naphthylalkanes by a Friedel‐Crafts acetylation of the two naphthalene groups followed by cyclization/dimerization of the resulting diketones by a McMurray reaction. The macrocyclic naphthalenophanes 6a and 6b exist in solution as a mixture of conformers while 7a and 7b were identified as the anti isomers.
A Convenient Synthesis of Macrocyclic[2.1.2.1]Paracyclophanes
Authors: Grützmacher Hans‐Friedrich , Mehdizadeh Ahmed , Mülverstedt Astrid 
Published: July 2007

AbstractThe [2.1.2.1]paracyclophanedienes 9–11 were prepared in good yields by a McMurry cyclization of the bis(4‐acylphenyl)methanes 5 and 6 and of bis(4‐acetylphenyl) ether (7), respectively.
Zur Chemie des Galliums, IV. Darstellung und Strukturen monomerer (2,2,6,6‐Tetramethylpiperidino)gallane
Authors: Linti Gerald , Frey Ronald , Polborn Kurt 
Published: July 2007

On the Chemistry of Gallium Compounds, IV. ‐ Synthesis and Structure of Monomeric (2,2,6,6‐Tetramethylpiperidino)‐gallanesMonomeric dimethyl‐ and diethyl(2,2,6,6‐tetramethylpiperidino) gallanes have been synthesized and spectroscopically characterized. Starting from bis(2,2,6,6‐tetramethylpiperidino)gallium halides (tmp)2GaX (16, 17, X=Cl, Br) various (aryloxy)‐ and organylbis (amido) gallium compounds (tmp)2GaY (18–21, Y = OAr, Ph, Me) have been obtained. The crystal structures of (tmp)2GaOPh (18) and (tmp)2GaPh (20) show trigonal planar‐coordinated gallium atoms. Planarcoordinated nitrogen atoms with a GaN bond length of 188 pm are present in 20. In contrast, 18 shows one planar‐ and one slightly pyramidal‐coordinated nitrogen atom, and this results in two different bond lengths of 184.9 and 181.8 pm, respectively.
Derivate des Imidazols, XI. (C8H14N2)M(CO)5 (M = Mo, W) ‐ Terminale Koordination eines Olefins in Pentacarbonylmetall‐Komplexen
Authors: Kuhn Norbert , Bohnen Hans , Bläser Dieter , Boese Roland 
Published: July 2007

Imidazole Derivatives, XI. ‐ (C8H14N2)M(CO)5 (M = Mo, W) ‐ Terminal Coordination of an Olefin in Pentacarbonyl Metal ComplexesHerrn Professor Reinhard Schmutzler zum 60. Geburtstag gewidmet.
The 2‐methylenimidazoline complexes (C8H14N2)M(CO)5 (M = Mo, W; 6) are obtained from M(CO)6 and 1,3,4,5‐tetramethyl‐2‐methyleneimidazoline (5). Spectroscopic data reveal the strong donor character of the ylidic ligand in 6. The end‐on coordination mode of the olefin is demonstrated by an X‐ray structure analysis of 6a.
Umsetzung von Isothiocyanaten und Isonitrilen mit R2Al–AlR2 [R = CH(SiMe3)2]; ein‐ und zweifache Insertion von Isonitril in die Aluminium‐Aluminium‐Bindung
Authors: Uhl Werner , Schütz Uwe , Hiller Wolfgang , Heckel Maximilian 
Published: July 2007

AbstractReaction of Isothiocyanates and Isonitriles with R2Al–AlR2 [R = CH(SiMe3)2]; Single and Double Insertion of Isonitrile into the Al–Al BondTetrakis[bis(trimethylsilyl)methyl]dialuminium(4) 1 reacts with phenyl or tert‐butyl isothiocyanate with cleavage of the C = S double bond. Two compounds are formed: R2Al‐S‐AlR2 [R = CH(SiMe3)2] 3 and R2Al‐C(NR')‐AlR2 (4 R' = C6H5; 5 R'= CMe3) with a sulfur atom or an isonitrile group inserted between the aluminium atoms. Compounds 4 and 5 were isolated in high yield by the reaction of 1 with the appropriate isonitriles. By using an excess of phenyl isonitrile a dark red compound 6 is obtained with two isonitrile units inserted into the Al–Al bond and formation of a C–C single bond. According to crystal structure determinations of 4 and 6 a three‐membered heterocycle is formed by the interaction of the nitrogen lone‐pair to one of the Al atoms in 4, while in 6 both Al atoms are four‐coordinated by bonding to a nitrogen and a carbon atom with formation of two across the C–C bond anellated four‐membered heterocycles. As shown by NMR spectroscopy the molecular structure of 4 with one stereochemically saturated and one unsaturated Al atom is unchanged in solution even upon heating to 100°C.
Twofold Deprotonated Citric Acid as a Bidentate Ligand of Pentacoordinate Silicon: Synthesis and Structural Characterization of the Zwitterionic λ5Si‐Spirosilicate Bis[citrato(2–)‐O3,O4][(dimethylammonio)methyl]silicate Hydrate
Authors: Mühleisen Mathias , Tacke Reinhold 
Published: July 2007

AbstractThe zwitterionic λ5Si‐spirosilicate bis[citrato(2–)‐O3,O4][(dimethylammonio)methyl]silicate (4) was synthesized by reaction of (MeO)3SiCH2NMe2 (3) with citric acid (molar ratio 1:2) in acetonitrile at room temperature and isolated, after crystallization from water, as the hydrate 4 . H2O (yield 81%). The crystal structure of 4 . H2O was studied by single‐crystal X‐ray diffraction. The alcoxide oxygen atoms and central carboxylate oxygen atoms of two citrato(2–) ligands and one carbon atom coordinate to the silicon atom of 4 . H2O. The coordination polyhedron around the pentacoordinate silicon atom (SiO4C framework) can be described as a distorted trigonal bipyramid, the two carboxylate oxygen atoms occupying the axial sites. The λ5Si‐silicon(IV) complex 4 also exists in solution (DMSO, H2O).
Synthesis, Absorption Spectra, and Photostability of Triarylmethane Dye Ethynylogues Containing Trifluoromethyl Group(s)
Authors: Muramatsu Hiroshige , Okumura Akinori , Shibata Katsuyoshi , Matsui Masaki 
Published: July 2007

AbstractTriarylmethane dye ethynylogues 7′– 11′ containing trifluoromethyl group(s) are synthesized in moderate to good yields by treating 1,1,3‐triaryl‐2‐propyn‐1‐ols, prepared from diaryl ketones and lithium arylacetylides bearing trifluoromethyl group(s), with perchloric acid. The first absorption bands of a series of triarylmethane dye ethynylogues containing trifluoromethyl group(s) 11′ are observed around 700 nm. The photostability of the triarylmethane dyes is also examined.
Synthesis and Characterization of Nitrido(tetra‐tert‐butylphthalocyaninato)‐ rhenium(V) and Nitrido(phthalocyaninato)rhenium(V)
Authors: Ziener Ulrich , Hanack Michael 
Published: July 2007

Abstract4‐tert‐Butylphthalodinitrile (1) reacts with ammonium perrhenate, NH4ReO4, to yield nitrido(tetra‐tert‐butylphthalocyaninato)rhenium(V), (tBu)4PcReN (2), which is characterized by IR, UV/Vis, CV, MS, 1H and 13C NMR, and elemental analysis. It shows good solubility in common organic solvents. In solution 2 is assumed to be monomeric whereas in the solid state also dimers or higher aggregates are present. From the NMR spectra it is concluded that different constitutional isomers of 2 are formed but not in the expected ratio of a statistical distribution. By analogy with 2, the already known nitrido(phthalocyaninato)rhenium(V), PcReN (3), is prepared for comparison.
Synthesis and Thermolysis of a Chiral, Non‐Racemic Iminoaziridine11
Authors: Quast Helmut , Aldenkortt Sven , Heller Eberhard , Schäfer Peter , Schmitt Edeltraud 
Published: July 2007

AbstractThe 2‐halo imidoyl chlorides 7 are obtained from the amide 5 and the 2‐halo amides 6 by the action of phosphorus pentachloride and thionyl chloride, respectively. Non‐racemic (S)‐6a is converted into 7a which is racemic, however. The reaction of Lawesson's reagent with 6a furnishes the diaste‐reomeric 1,3,2‐thiazaphospholidine derivatives 15. Treatment of (S)‐6a (98% ee) with methyl triflate affords 2‐chloro imidate 8 (95% ee) which reacts with methanamine in the presence of methanammonium chloride to yield the 2‐chloro amidine (S)‐9a (90% ee). The 2‐halo imidoyl halides 7a and b react with methanamine to produce the 2‐halo amidines 9a and b. — Strong bases, e.g. potassium tert‐butoxide or sodium hydride in the presence of catalytic amounts of tert‐butyl alcohol, eliminate hydrogen chloride or bromide from the 2‐halo amidines 9a and b and (S)‐9ato yield mixtures of the 2‐iminoaziridines (E)‐ and (Z)‐4, and (E,R)‐ and (Z,R)‐4 (83% ee), respectively. The 1,3‐elimination of hydrogen bromide from 9b is diastereoselective at ‐30 to ‐40° [(E)‐4:(Z)‐4 = <10:>90]. The diastereomers equilibrate at 36° with (kEZ + kZE) = (5.92 ± 0.08) . 10−5 s−1 (K = kEZ/kZE = 0.428 ± 0.013). ‐ The thermolysis of (E)‐ and (Z)‐4 in [D6]benzene solution yields the imine 16 and methyl isocyanide (17). The decomposition follows the first‐order rate law. The following Arrhenius and Eyring parameters are calculated from five rate constants obtained in the temperature range of 70–110°: Ea = (115.2 ± 0.4) kJmol−1, IgA = (12.06 ± 0.28), δH‡ = (112.1 ± 0.4) kJmol−1, δS‡ = (‐23.9 ± 0.7) JK−1 mol−1, δG‡373K = 121 kJmol−1. The enantiomeric excess of the surviving fraction of (E,R)‐ and (Z,R)‐4 is unchanged after two half‐lives at 80°.
Enantioselective Synthesis of Polyfunctional Small Building Blocks with a Quaternary Stereogenic Center
Authors: Enders Dieter , Zamponi Andreas , Schäfer Thomas , Nübling Christoph , Eichenauer Herbert , Demir Ayhan Sitki , Raabe Gerhard 
Published: July 2007

AbstractApplication of the SAMP‐/RAMP‐hydrazone method offers an efficient and flexible access to compounds with a quaternary stereogenic center. Examples bearing silyl, thio, phenyl, aldo, keto, ester, and alkyl functionalities are described. The 2‐phenylaldehydes and ‐ketones and the β‐keto esters 4 were obtained in good overall yields and with variable enantiomeric excesses. The synthesis of the thiolated 2‐formyl and 3‐formyl carboxylic esters 12 was achieved in high overall yields and with high enantiomeric excesses. The silylated carboxylic ester and acids 16 were produced in moderate to high overall yields and with moderate to excellent enantiomeric excesses, depending on the electrophile used for the quaternization. The absolute configurations of the compounds 12 and 16 were determined by X‐ray structure analyses, and the mechanism of the quaternization is postulated.
LiClO4‐induzierte Dreikomponenten‐Aminoalkylierung von Aldehyden
Authors: Reza Saidi M. , Heydari Akbar , Ipaktschi Junes 
Published: July 2007

AbstractLiClO4 Induced One Pot Three‐Component Aminoalkylation of AldehydesLiClO4‐mediated one‐pot reaction of isobutyraldehyde (1) or benzaldehyde (5) with (trimethylsilyl)dialkylamines 2 and C nucleophiles such as O‐silylated ketene acetals 3, 6, allyl Grignard, lithium (trimethylsilyl)acetylide, triinethylsilyl cyanide, and diethylzinc afforded in high yields the corresponding aminoalkylation products 4 and 7–13. The lithium enolate of cyclohexanone adds in 5 M LiClO4 solution in an Ik manner to the corresponding mannich base (19, 20) with good yield.