The Synthesis of Steroidal 4, 22, 25-Trien-3-Ones

The occurrence of δ22,25-sterols has been reported in a number of plants.^1–6 From a chemical point of view, it seems that such systems would be ideal for the alkylation of the side chain of cholesterol to give that of ergosterol, sito-sterol and stigmasterol. Furthermore, such dienes would give by hydration ecdysone-like compounds. Sih and Whitlock³ have discussed recently the involvement of a diene intermediate in the biosynthesis of plant sterols.     

A non‐linear optical crystal,Cd3Zn3(BO3)4

The title compound, tricadmium trizinc tetraborate, Cd₃Zn₃(BO₃)₄, is a new non‐linear optical (NLO) crystal and its structure has been determined by single‐crystal X‐ray diffraction. This compound is composed of planar [BO₃]³⁻ groups sharing O atoms with CdO₄ or ZnO₄ tetrahedra. The BO₃ triangles are located on threefold axes and are arranged with nearly the same orientation. The Cd and Zn atoms are disordered on the same site in the proportion 1:1. A strong second harmonic generation of Nd:YAG laser radiation (λ = 1064 nm) has been observed for a crystal of the title compound.     

K2Zn3O4 und Rb2Zn3O4, zwei neue Oxozincate mit Gerüststruktur [1]

K₂Zn₃O₄ and Rb₂Zn₃O₄, Oxozincates with Framework Structure For the first time single crystals of K₂Zn₃O₄ were obtained by heating mixtures of the binary oxides (K: Zn = 2.2:3) in sealed Ag- or Pt-capsules at 800°C (5 w). Powder of this colourless and moisture-sensitive oxide was prepared analogously at 500°C. It crystallizes monoclinic, space group C2/c with a = 1482.7(2), b = 637.3(1), c = 571,9(1) pm, β = 102.79(1)°, Z = 4, d_x = 4.265 g/cm³, d_pyk = 4.00 g/cm³. The crystal structure was determined from four-circle diffractometer data (MoKα, 730 unique hkl) and refined to R = 5.9%, R_w = 6.4%. It shows a Zn₃O₄ framework which consists of SiS₂-like chains [ZnO_4/2] connected by puckered layers of [ZnO_3/3]. The crystal structure can be derived from a cubic closet packing of O^2? and K⁺. Effective Coordination Numbers and the Madelung Part of Lattice Energy (MAPLE) are calculated. Rb₂Zn₃O₄ was prepared from the binary oxides at 400°C (colourless hygroscopic powder). According to powder data it crystallizes isostructural to K₂Zn₃O₄ with a = 1523.5(4), b = 649.8(2), c = 574.0(2) pm, β = 101.43(3)°, Z = 4, d_x = 5.141 g/cm³, d_pyk = 5.20 g/cm³.     

Die Schmelzdiagramme der Systeme CsN3/Zn(N3)2 und KN3/Zn(N3)2

The phase diagrams of the systems CsN₃/Zn(N₃)₂ and KN₃/Zn(N₃)₂ have been obtained employing the microscopic technique ofL. Kofler andA. Kofler. Within the system CsN₃/Zn(N₃)₂ three eutectics at 148°C, 142°C, and 210°C were found. Besides Cs₂Zn(N₃)₄, melting incongruently in the interval 153°C to 170°C, there exist two further compounds of the most probable composition Cs₃Zn₂(N₃)₇ and CsZn₂(N₃)₅, melting congruently at 170°C and 210°C, resp. In the system KN₃/Zn(N₃)₂ there exist two eutectics at 203°C and 172°C and two compounds, one of them, i.e. K₂Zn(N₃)₄, melting congruently at 206°C, the other one, with composition KZn₃(N₃)₇ or KZn₄(N₃)₉, melting incongruently at 210°C.

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Mit 8 Abbildungen

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Herrn Professor Dr.Heribert Grubitsch zum 70. Geburtstag gewidmet.     

Editorial board page for “Synthetic Communications”, Volume 22, Number 3

This is a scanned image of the original Editorial Board page(s) for this issue.     

Synthesis and structure of a novel supramolecular Zn3Co8 assembly containing a linear Zn3 core

Reaction of Zn(OAc)(2).2H2O (OAc = acetate) with LH2 in THF followed by reaction with Co2(CO)8 yields the novel supramolecular assembly Zn3L2(OAc)2[Co2(CO)6](4).0.5CH2Cl2, which was characterized by X-ray diffraction (LH2 = (CH2)3(N=CH-2-OH-5-C identical to CSiMe3C6H3)2 or N,N'-propylenebis(2-hydroxy-5-trimethylsilylethynl-1-aldimine).     

Structural, electronic, and optical properties of oxygen defects in Zn3N2

The structural, electronic, and optical properties of oxygen-defective Zn(3)N(2) were studied by means of density functional theory. The geometry optimization result shows that pure Zn(3)N(2) is cubic in structure, which is in agreement with experiment. Our results indicate that Zn(3)N(2) with nitrogen replaced by oxygen is more stable than that with interstitial oxygen and the substitutional oxygen for nitrogen in defective Zn(3)N(2) is responsible for the n-type conduction character. The possible optical transition mechanisms are discussed.     

The stereospecific synthesis of inotodiol 3β, 22R-dihydroxylanosta-8,24-diene

Inotodiol 1a has been stereospecifically synthesised from lanosterol in six steps and Horeau's method utilised to demonstrate the R-configuration at C-22.