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Crystals of the title compound are prepared by hydrothermal reaction of La2O3, 37 wt% H2SO4, and 3-aminobenzoic acid in presence of NH4OH (autoclave, 433 K, 3 d) followed by slow solvent evaporation.

Axial-chiral binaphthalene is obtained by Suzuki—Miyaura reaction of naphthaleneboronic acid and bromo methylnaphthalene in the presence of newly synthesized chiral P,O ferrocenyl ligands.

In this account, the recent advances on chiral stereochemically dynamic 2,2’-biphosphole ligands for applications in asymmetric catalysis are reported. In the first part, the synthesis of stereodynamic diphosphines and diphosphinites derived from 2,2’-biphosphole is presented. The second part describes the kinetic dynamic resolution to give diastereo- and enantiopure complexes. Applications in asymmetric allylic substitution, hydroformylation and hydrogenation are presented in the last part.

Reaction of organometallic reagents with a chiral glycine template derived from glyoxal serves as a keuy step in assymetric syntheses of the title products.

The formation of heterobicycles by condensation of (1R, 2R)-(−)-pseudoephedrine or (1R, 2S)-(−)-ephedrine with glyoxal is reported. In the case of pseudoephedrine, the nuclear magnetic resonance data of the crude reaction mixture indicate the presence of three isomeric compounds (5, 6, and 7), which were separated by fractional crystallization, while ephedrine afforded the oxazino-oxazine 8 and the known (5S*,6R*)-4,5-dimethyl-6-phenyl-1,4-oxazin-2-one (9). Conclusive spectroscopic evidence for the structures of the new compounds having the cis-[1,4]oxazino[3,2-b]-1,4-oxazine (5 and 8) and the 2,2′-bioxazolidine type structures (6 and 7) was obtained by measurement of the 13C satellite coupling constants in the 300 MHz 1H nmr spectra, combined with the evaluation of dihedral angles using a modified Karplus type relationship. Unequivocal 1H and 13C nmr spectral assignments for all new compounds were done using two-dimensional carbon–proton correlation experiments. Syntheses of the known 5a,6,11a,12-tetrahy...

A comprehensive review of the chemistry of metal carbonyl cluster complexes containing ynamine ligands including syntheses, structures, bonding, and reactivity is presented.

(−)-Norephedrine and (−)-norpseudoephedrine undergo condensation with a wide variety of 1,2-diketones to yield the corresponding 2-hydroxy-5,6-dihydro-2H-1,4-oxazines with high regio- and stereoselectivity. The X-ray structure analysis of five of the compounds studied shows that the stereochemistry at the newly formed stereogenic center is S in all cases.

The crystal structures of three key intermediates in the synthesis of 2,2'-biphosphole are reported. Molecules of 2,5-dibromo-3,4-dimethyl-1-phenyl-2,5-dihydro-phosphole 1-oxide, C 12 H 13 Br 2 OP, and 2,5-dibromo-3,4-dimethyl-1-phenyl-2,5-dihydrophosphole 1-sulfide, C 12 H 13 Br 2 PS, each contain a phospholene ring with a chair conformation. In the molecules, the α-H atoms are trans to the P=O or P=S groups, thus demonstrating that the sulfurization takes place with the retention of the stereochemistry at phosphorus. In 2-bromo-3,4-di-methyl-1-phenylphosphole 1-sulfide, C 12 H 12 BrPS, the phosphole ring is perfectly planar.

A zwitterionic cyanine dye of formula HOCH2CH2(NC5H4)CHCH(C6H4)O (M2) is reported with its crystal structure. Crystal data: monoclinic (P21), a=15.038, b=5.385, c=17.301 A, β=111.68, Z=2. The nonlinear optical properties are investigated through solvatochromism and found to be very similar to those of a related cyanine dye (M1) having an extremely high molecular hyperpolarizability (β). INDO calculations performed on both crystal structures indicate small modifications in the electronic properties, but which result in a large modification of the hyperpolarizability in the solid: β(M2)=2.5×β(M1). In addition, the hydroxyethyl substituent can be employed for engineering the chromophore into acentric environments. Therefore, increasing NLO responses may be expected at both the molecular and macroscopic levels with such systems.

A simple and efficient method for the synthesis of larger polyaza heterocyclic structures 6a, 6b and 8 with 1,3-pyrimidine units has been developed, based on the reaction of enaminones with appropriate guanidines or carboxamidines under basic conditions. Using this procedure, several new, optically active polyaza heterocycles 10, 12 and 13 have been prepared in good yields, from enantiomerically pure Nα-Boc-L-arginine as guanidine reagents.

The unsymmetrical substituted zirconacyclopentadienes obtained by selective intramolecular cross-coupling of two different alkynes on zirconocene are used to prepare new unsymmetrical C-substituted phosphole compounds. The X-ray structures of a phosphole and its related sulfide are presented.

We, the named authors, hereby wholly retract this Communication. Signed: Frederic Pezet, Hassan Ait-Haddou, Jean-Claude Daran, Isabelle Sasaki and Gilbert G. A. Balavoine; Toulouse, France and Austin, TX, USA, 3rd March 2004 Retraction endorsed by Sarah Thomas, Managing Editor, Chemical Communications

A convenient one-pot procedure for the preparation of 1-(diisopropylamino)phospholes has been developed. These phospholes have been used in a multistep procedure for synthesizing two new 2,2′-biphosphole disulfide compounds. The structures and stereochemistry of these compounds have been studied by X-ray diffraction analysis and by molecular modeling. The 1-(diisopropylamino) group, used as a bulky substituent on the phosphorus atom in combination with a phenyl group on the ring, proved to be an important factor in the stabilization of the axial chirality of 2,2′-biphosphole framework.

Pyridine and bis(TMS)ketene acetals (TMS = trimethylsilyl) react successively with methylchloroformate and iodine (or peracids) to give, via functionalized dihydropyridines, bicyclic nitrogen-containing lactones which have been characterized by X-ray crystallography.

Various new chiral ferrocenyl phosphine-thioethers and thiophosphine-thioethers with planar chirality only have been efficiently synthesized with good overall yields (39–43%) in enantiomerically pure form by a nine-step sequence involving the introduction of the planar chirality by Kagan’s acetal method. These new P,S and S,S ligands have been successfully used in the palladium-catalyzed asymmetric allylic substitution reaction (ee up to 93%).

Herein we report an efficient one pot synthesis of new chiral 4,5-dihydro-4-arylspiro[1,3,4-thiadiazole]-5,2′-camphane-2-carboxylic acid ethyl esters 5–7 and 4,5-dihydro-3-arylspiro[1,4,2-oxathiazole]-5,2′-camphane 11–13, using 1,3-dipolar cycloaddition of nitrilimines 2–4 and nitrile oxides 8–10 to (1R)-thiocamphor 1 respectively. The structure of the newly prepared 1,3,4-thiadiazoles 5–7 (obtained as pure diastereoisomers) were fully established via spectroscopic analysis and X-ray structural analysis which proved the absolute configuration of the C5 spiranic carbon to be (R). NMR spectral analysis were also very useful to show the new 1,4,2-oxathiazoles 11–13 are mixtures of two (5R)/(5S) diastereoisomers with the ratio 6:4,7:3 and 6:4 respectively.

International audience; TiCl3 is oxidized by SOCl2 in the presence of the appropriate amount of [NEt3Bz]Cl or [PPN]Cl [Bz = benzyl; PPN = bis(triphenylphosphanyl)iminium] to afford the corresponding salts of [Ti2Cl9]−, [Ti2Cl10]2− or [TiCl6]2−. The results of cyclic voltammetric and solution IR studies in the Ti−Cl stretching region are interpreted in terms of a rapid chloride-redistribution equilibrium between [Ti2Cl10]2− on one side and a mixture of [Ti2Cl9]− and a previously unreported [Ti2Cl11]3− species on the other side. In the solid state, however, a compound with the [PPN]3[Ti2Cl11] stoichiometry exists as a mixture of [PPN]2[Ti2Cl10] and [PPN]2[TiCl6]. The PPN salt of [Ti2Cl9]− has been structurally characterized by X-ray diffractometry. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The complexes {Li(THF)4}{Ln[(R)-C20H12N2(C10H22)]2} (Ln = Sm, Yb) have been synthesized, fully characterized and found to be efficient and enantioselective catalysts for intramolecular hydroamination of 1-(aminomethyl)-1-allylcyclohexane.

The title compound, namely octa­aqua­ytterbium(III) aqua­nona­chloro­tricadmate(II) hexa­hydrate, [Yb(H2O)8][Cd3Cl9(H2O)]·6H2O, was prepared by evaporation at 278 K from an aqueous solution of the ternary system YbCl3–CdCl2–H2O and was characterized by elemental chemical analysis and by X-ray powder and single-crystal diffraction studies. The crystal structure can be viewed as being built from layers of double chains of CdCl6 and CdCl5(H2O) octahedra separated by antiprismatic [Yb(H2O)8]3+ cations. The stabilization of the structure is ensured by O—H⋯O and O—H⋯Cl hydrogen bonds. A comparison with the structures of SrCd2Cl6·8H2O and CeCd4Cl11·13H2O is presented.

A simple and efficient method for the synthesis of new chiral polyaza heterocylic structures containing pyridines and 1,3-pyrimidine units has been developed. It is based on the reaction of the appropriate enaminones with optically pure carboxamidine derived from the commercially available (R)-(−)-myrtenal.

Reaction between Y5O(OiPr)13 and acetylacetone at room temperature under anhydrous conditions, produced in high, reproducible yield a compound characterized—by 1H and 13 C NMR, as well as X-ray diffraction—as Y2(μ2-OAc)2(acac)4(H2O)2. It crystallizes in the orthorhombic Pcnb system, with unit cell dimensions a = 13.385 (3), b = 15.107(4), c = 16.100(4) A and Z = 4. Least-squares refinement converged to a final R = 0.0356. The molecule is a centrosymmetric dimer with chelating tridentate acetato groups in the bridging positions. The yttrium atoms are eight-coordinated, with a distorted square antiprism geometry. Intra- as well as intermolecular hydrogen bonding between the water molecules and the β-diketonato ligands is observed. The formation of this acetatoacetylacetonate derivative as well as its behaviour in solution are discussed.

2-Methylaziridine H NCH 2 C HCH 3 reacts with alkyl- and aryl-(alkoxy)carbene complexes of chromium and tungsten to give alkyl- and aryl-aziridinocarbene complexes. The latter undergo a thermal transformation to give olefins and alkyl- or aryl-nitrilechromium pentacarbonyl complexes, e.g. (CO) 5 CrNC- o -tolyl (which has been characterized by X-ray crystallography). 2-Phenylaziridine H NCH 2 C HPh in turn reacts with the carbene complexes to give directly styrene and the acetiminoester complexes (CO) 5 WHNC(CH 3 )OCH 2 CH 3 and (CO) 5 CrHNC(CH 3 )OCH 2 -CH 3 . The latter gives, upon hydrolysis (CO) 5 CrNH 3 . The structures of (CO) 5 WHNC(CH 3 )OCH 2 CH 3 and (CO) 5 CrNH 3 have been determined by X-ray diffraction. The mechanisms of the two reactions are discussed.

Tris(tetraphenylimidodiphosphinato)praseodynium reacts with ammonium or potassium salts of carboxylic acids to give dinuclear dicarboxylato complexes, the structure of which has been established and which can be used for the determination of the enantiomeric purity of carboxylic acids.

Chromium aminocarbene complexes (CO) 5 CrC(CH 3 )N(CH 2 Ph)(CH 3 ) ( 3 ), (CO) 5 CrC(H)N(CH 2 Ph)(CH 3 ) ( 5 ) and (CO) 5 CrC(H)N(CH 2 CHCH 2 )(CH 3 ) ( 7 ) react with diphenylacetylene in boiling benzene to give, after insertions of the alkyne and CO and migration of the benzyl or the allyl group from nitrogen to carbon, substituted 2- and 3-pyrrolinones ( 10–15 ). The structures of (CO) 5 -CrC(CH 3 )N(CH 2 Ph)CH 3 ( 3 Z ) ( R 0.031 R w 0.030) and of the chromium tricarbonyl complex of the pyrrolinone 10 , (CO) 3 Cr (C 24 H 23 ON) ( 9 ) ( R 0.034 R w 0.035) were determined by the X-ray diffraction.

A chromium carbene complex (2) bearing a 2-methylaziridine ring system on the carbene carbon atom easily undergoes a double diphenylacetylene and a single CO insertion reaction to give a 1-oxotetrahydroindolizine derivative (4), which has been fully characterized by X-ray analysis of its Cr(CO)3 adduct (3).

The crystal structure of the di-5,6-dihydropyrimidino [5,4- c ] carbazole hexachloroplatinate(IV) monohydrate has been determined by X-ray analysis. The compound crystallizes in the monoclinic space group P 2 1 / m with cell dimensions a = 8.697(3), b = 22.895(5), c = 7.808(1) A, β = 108.65(2)°, Z = 2. The structure was refined to R = 0.027 and R w = 0.027 with use of 2302 independent reflections. The platinum and four (among the six) chlorine atoms which are bound to the metal and the water molecule lie in the mirror plane ( y = ± 1 4 ). In the DPCH + cations, the cyclohexadiene ring remains in a skew-chair conformation. In a previous paper [1], we described the synthesis and crystal structure of the tetra-5,6-dihydropyrimidino [5,4- c ] carbazole dichloride hexachloroplatinate (IV) tetrahydrate. By modifying the experimental procedure, one new compound was synthesized corresponding to the formula [C 14 N 3 H 12 + ] 2 [PtCl 6 ] 2− ·H 2 O.

The chloride-bridged cyclopalladated dimers (I) react with alkynes to afford organometallic products in which one, two, or three alkynes are inserted into the Pd-C bonds; the ratio of alkyne:Pd in the final products being independent of the stoichiometry of the reaction.