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Isoalangidiol (3α,18α-B':A'-neogammacerane-3,18-diol) has been extracted as a natural product from the leaves of Alangium lamarckii Thw. (Alangiaceae). The crystal structure study of its monoacetate, C32H54O3, was undertaken in order to ascertain the conformation of the compound. The four six-membered rings are in chair conformations. The five-membered ring is distorted from a plane and is twisted, with a C19—C18—C17—C21 torsion angle of −43.0 (4)°. The molecular parameters of the compound are all within normal limits.

In the title compound, C14H19IN2O8, an almost planar heterocyclic base is oriented anti with respect to the puckered sugar moiety. The sugar pucker is C2′-endo/C3′-exo, the N-glycosidic torsion angle is 166.4 (4)° and the conformation of O5′ is +sc. The mol­ecules are linked by hydrogen bonds of the types N—H⋯O and O—H⋯O.

[4+2] cycloaddition reactions of 1-aryl-4-dimethylainino-1,3-diaza-1, 3-butadienes ( 1 ), 1 -aryl-4-dimethylamino-2-methylthio-1, 3-diaza-1, 3-butadienes ( 5 ), 1-aryl-4-methylthio-2-phenyl-4-sec. amino-1, 3-diaza-1, 3-butadienes ( 9 ) and 4, 4-bis(sec.amino)-1,2-diphenyl-1, 3-diaza-1, 3-butadienes ( 12 ) with monophenyiketene and similar cycloaddition reactions of 1 , 5 and 12 with monochloroketene are described.

α-Nitrosostyrenes ( 2 ), generated in situ, underwent unusual regioselective [3+2]cycloadditions with 1,3-diaza- 1,3-butadienes ( 1 ) leading to cyclic nitrones ( 5 ) in good yields. They also gave cyclic nitrones ( 8 ) with trisubstituted amidines ( 7 ).

The glycosidic torsion angle, χ, of the title compound, C 10 H 11 N 3 O 4 , has a value of -150.5(3)° in the anti range. The sugar pucker is 2 T 3 and the C4'-C5' conformation is +sc with γ=44.6 (5)°. The isocyanide moiety is linear and the pyrimidine ring is planar. The molecular packing is stabilized by a network of hydrogen bonds and van der Waals interactions.

The title compound, 1-(2,3-dideoxy-2,3-difluoro-β-d-ribopentofuranosyl)thymine, C10H12F2N2O4, consists of an almost planar heterocyclic base moiety oriented anti with respect to a puckered sugar moiety. The sugar pucker is 2T3 and the N-glycosidic torsion angle is −119.6 (2)°. The conformation of the O5′ atom is +sc and the molecules are held together by a network of N—H⋯O and O—H⋯O hydrogen bonds.

An efficient trans diastereoselective synthesis for azetidinones 3 having 3-dienyl functionalities was developed. The method first involved the [2 + 2] cycloaddition of butadienylketene with variou...

In the title compound, methyl 2-{6′-ethyl-2′,3′,5′,6′,7′,8′-hexahydro-4-hydroxy-2-oxo- spiro­[1H-indole-3(2H),1′(8a'H)-indolizin]-7′-yl}-3-methoxyacrylate, C22H28N2O5, the indole molecule is not planar. The planarity of the atom group C13—N1—C2=O1 of the indole moiety and the short N1—C2 bond of 1.363 (11) A are due to delocalization of the benzoid electrons, which extend over the atoms N1, C2 and O1. The five-membered ring of the indolizine moiety is puckered and the six-membered ring fused to it has a normal chair conformation. The methoxy­carbonyl and the methoxy groups have a trans configuration about the C16 =C17 bond in the acrlyl moiety. The structure is stabilized by intramolecular hydrogen bonding of the type O—H⋯N and intermolecular hydrogen bonding of the type N—H⋯O.

The title compound (systematic name: 3,6,6,14-tetramethyl-10-methylene-2,7-dioxobicyclo[10.3.0]pentadeca- 4-ene-1,9,11,13,14-pentayl pentaacetate; C30H40O12) is a new diterpene oligoester. The structure consists of a five-membered and a twelve-membered ring, both of which are nonplanar. They are inclined to each other at an angle of 28.89 (15)°. The five-membered ring has an envelope conformation.

Novel shape- and structural-controlled superparamagnetic nanostructures composed of self-supported spherical and rod-like CoFe2O4 colloidal nanocrystals have been prepared by thermolysis of a stoichiometric Co2+Fe23+−oleate complex in organic solution with periodic injection of hexane for controlling the nucleation, assembly, and growth of the nuclei.

We show that the variation of T c in Er(Ni 1− x Pt x ) 2 B 2 C ( T c ∼ 10.6 K and T N ∼ 5.7 K for x = 0) as a function of x proceeds in two steps: strong decrease of T c for initial values of x (0 ≤ x T c = 7.3 K at x = 0.1) and, thereafter, a relatively much weaker drop (almost a plateau) of T c with further increase of x . T N exhibits a slight, almost linear, decrease over the entire range of x studied here; T N = 4.7 K for x = 0.2. Our results for x = 0.10 are in sharp disagreement with the results, namely, T c T N , as reported by Felner et al. [I. Felner, D. Schmitt, B. Barbara, C. Godart, E. Alleno, J. Solid State Chem. 133 (1997), 5].

We report the results of detailed magnetic studies on binary rare-earth–transition metal compound YPd 3 . The results of temperature and magnetic field dependent DC-magnetic measurements along with the results of powder X-ray diffraction measurement and electrical transport have been discussed. The X-ray data suggest a well-defined ordered crystal lattice, free from any detectable impurity phase. Magnetization data exhibits predominant diamagnetic character at higher fields. However, the compound exhibits anomalous behavior at low fields.

An efficient three-step route for the synthesis of N-1 alkyl/aryl-substituted hydantoins was developed from inexpensive commercially available substrates. The reaction of amines with cyanogen bromide takes place to give monoalkyl/aryl cyanamides. This on treatment with methyl bromoacetate in the presence of sodium hydride in tetrahydrofuran affords methyl N-cyano-N-alkyl/arylaminoacetate, which undergoes hydrolysis and cyclization in the presence of 50 % H2SO4 to afford N-1 substituted hydantoins in very good-to-excellent yields. Wide varieties of final products having primary, secondary, tertiary, and aryl substituents at the N-1 position were successfully synthesized by this method. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

Polycrystalline samples with nominal formula CeM2B2C (M=Fe, Co, Ni, Cu, Ru, Rh, Pd, Os, Ir, Pt and Au) were prepared by arc melting. CeM2B2C essentially forms as a single phase with the LuNi2B2C-type structure only for M=Co, Ni, Rh, Pd, Ir and Pt. CeOs2B2C exists as a minority phase in the corresponding alloy. No CeM2B2C phase could be detected in the alloys melted with M=Fe, Cu, Ru, and Au. Highly accurate structural parameters were obtained by single crystal diffractometry on CeRh2B2C and CeIr2B2C. None of these compounds exhibits superconductivity or magnetic order down to 2 K. From X-ray absorption spectroscopy (XAS) measurements, we conclude that the Ce ions have a non-integer valence in CeM2B2C (M=Co, Ni, Rh, Ir), but are nearly trivalent in CePd2B2C (in contrast to an earlier report) and in CePt2B2C. The magnetic and valence properties of the CeM2B2C series show a regular evolution from delocalised to localised 4f-electron states driven by the value of the atomic radius of the M metal. For all these compounds, the Ce–Ce distances (‘a’ parameter) are larger than the Hill limit (≈3.4 A), clearly suggesting the importance of 4f–nd overlaps.