J. Feneau-Dupont

Asymmetric Aza-diels-alder Reaction Using the Chiral 1-phenyl-ethyl Imine of Methyl Glyoxylate

Abstract The Diels-Alder reaction between cyclopentadiene and the chiral 1-phenyl-ethyl imine of methyl glyoxylate takes place very easily by activation with trifluoroacetic acid and boron trifluoride etherate to provide diastereoselectively (total face selectivity and up to 98% exo selectivity) a near quantitative yield of 3- exo carbomethoxy -N-α-methylbenzyl-2-aza-5-norbornene adduct 4 resulting from unlike topicity.

Crystal-structure and Mossbauer Study of Trilithium Iron(iii) Trioxalate Pentahydrate

The crystal structure of the complex Li-3[Fe(C2O4)(3)]. 5H(2)O has been determined by X-ray diffraction analysis. The coordination of the iron atom is a distorted octahedron composed of the oxygen atoms of three oxalate ions. Two of the lithium ions are octrahedral and the third one is tetrahedral. Infinite chains appear along the b-axis, with alternation of Fe3+ and Li+ cations separated by oxalate anions. In agreement with this, the Mossbauer spectrum consists of an asymmetric and strongly broadened absorption pattern, indicating the presence of both paramagnetic relaxation effects and quadrupolar interaction which result from an Fe3+ interionic shortest distance of 6.559 Angstrom and from a non-cubic iron environment, respectively.

Crystal-structure and Mossbauer Study of Tetralithium Iron(iii) Trioxalate Chloride Nonahydrate

The crystal structure of the complex Li4[Fe(C2O4)3]Cl . 9H2O has been determined by X-ray diffraction analysis. It is composed of sheets perpendicular to the c-axis of the hexagonal cell. In the direction of c, short and long intervals, occupied by hydrated lithium ions, alternate between the sheets. The coordination is distorted octahedral for the iron ion, the chlorine ion and one of the lithium ions. It is nearly tetrahedral for the other lithium ions. The Mossbauer spectra are characterized by an asymmetric quadrupole doublet arising from a local distorsion of the iron octahedral coordination and the presence of a relatively fast spin-spin relaxation process.

Synthesis and Molecular-structure of (t-butylimido)tris(mesityl)(trimethylsiloxy)molybdenum(vi)

The reaction of Mo(O)(NBu(t))(OSiMe3)Cl or Mo(O)(NBu(t))(OSiMe3)2 with mesMgBr affords the imido complex [Mo(NBu(t))(mes)3(OSiMe3)] (2); the crystal structure of 2 indicates that the imido and the siloxy ligands are linear, the Mo-N bond of 1.786(10) angstrom being one of the longest reported to date for a linear molybdenum imido group.

Synthesis of Fused 1,2,4-thiadiazoles From 5-chloro-1,2,4-thiadiazol-3(2h)-ones

Fused 1,2,4-thiadiazoles (14-18 and 26-31) are conveniently prepared by reacting the chlorothiadiazolone 12 with omega-aminonitriles and aminoazoles. During these reactions the original thiadiazole ring is opened and a new, fused thiadiazole rig is formed, probably via a hypervalent sulfur intermediate. The products derived from the aminoazoles were analyzed by X-ray crystallography and found to have structures different from those published earlier.(7)

Structure of 7-methoxy-2-(2-methoxyphenyl)-4h-1-benzopyran-4-one (2',7-dimethoxyflavone)

C17H14O4, M(r) = 282.30, monoclinic, P2(1)/c, a = 12.498 (4), b = 9.490 (2), c = 12.184 (2) angstrom, beta = 107.87 (2)degrees, V = 1375.4 (6) angstrom 3, Z = 4, D(x) = 1.36 g cm-3, Cu K-alpha, lambda = 1.54178 angstrom, mu = 7.98 cm-1, F(000) = 592, T = 291 K, R = 0.042 for 1848 observed reflections. The benzopyran heterocycle is planar within experimental errors (max. deviation from the best mean plane through the ten atoms 0.031 angstrom). The dihedral angle between the heterocycle and the phenyl ring is 23.5 (5)degrees. The methoxy groups are nearly coplanar with their aromatic rings (torsion angles about C(arom)-O are 4-6-degrees).

A (2R,5S)‐2‐o‐anisyl‐3‐oxa‐1‐aza‐2‐phosphabicyclo[3.3.0]octane–borane complex

(2R,5S)-2-(2-Methoxyphenyl)-3-oxa-1-aza-2-phos-phabicyclo[3.3.0]octane(P-B)borane, C12H19BNO2P, is one of a series of new chiral oxazaphospholidine-borane complexes used as catalysts in the enantioselective borane reduction of ketones. The structure and the absolute configuration about the P atom were determined.

(2R,5S)-2,3-diphenyl-1,3,2-diazaphosphabicyclo[3.3.0]octane-borane

The title complex, C17H22BN2P, (3), is one of a series of new chiral diazaphospholidine-borane complexes used as catalysts in the enantioselective borane reduction of ketones. We describe herein the determination of the molecular structure of (3) and the absolute configuration about the P atom.

(Z)-(–)-(R)-β-Styryl p-tolyl sulfoxide

The crystal structure determination of Z-(-)-(R)-beta-styryl p-tolyl sulfoxide, C15H14OS, confirms its absolute configuration and establishes that the slightly twisted olefinic bond is not antiperiplanar to the S-O bond. It also provides a molecular basis for the theoretical study of cycloadditions between nitrones and vinylic sulfoxides.

8-(n-methyl-n-tosylamino)bicyclo[4.2.0]octane-7-spiro-2'-oxacyclopropane

C17H23NO3S, M(r) = 321.4, monoclinic, P2(1)/c, a = 8.724 (3), b = 12.009 (3), c = 15.780 (4) angstrom, beta = 91.81 (3)-degrees, V = 1652.4 (9) angstrom3, Z = 4, D(x) = 1.29 g CM-3, lambda(Mo Kalpha) = 0.71069 angstrom, mu = 2.08 cm-1, F(000) = 688, T = 291 K, R = 0.071 for 1671 observed reflections. In the four-membered ring the nitrogen substituent is exo; the ring is far from planar, with a dihedral angle about one diagonal of 32 (1)-degrees.