Measurements of someK-internal conversion coefficients near threshold

TheK-internal conversion coefficients have been measured by the XPG technique for a number of low energyγ-ray transitions whose energies do not exceed theK-binding energies by more than 4 keV. Using Si(Li) detectors in singles and coincidence arrangements, the following results were obtained: 63.1 keV El in¹⁶⁹Tm(α_K=1.02±0.15), 72.0 keV E1 in¹⁸⁷Re (0.75±0.05), 57.8 keV M1 in¹⁶²Ho (11.42±0.67), 56.6 keV M1 in¹⁶⁴Ho (12.04±0.70), and 67.1 keV M1 in¹⁷⁴Lu(10.25±0.58). The experimental results are compared with the theoretical calculations which include transition energies down to 1 keV above threshold.     

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KCd2[N(CN)2]5(H2O)4: an enmeshed honeycomb grid

The title compound, poly[potassium [diaquapenta‐μ₂‐dicyanamido‐dicadmium(II)] dihydrate], {K[Cd₂(C₂N₃)₅(H₂O)₂]·2H₂O}_n, contains two‐dimensional anionic sheets of {[Cd₂{N(CN)₂}(H₂O)₂]⁻}_n with a modified (6,3)‐net (layer group , No. 35). Two sets of equivalent sheets interpenetrate orthogonally to form a tetragonal enmeshed grid.     

Coulomb excitation studies of 160Dy, 162Dy and 164Dy

Coulomb excitation measurements with ¹⁶O and ⁴He projectiles have been performed on ¹⁶⁰Dy, ¹⁶²Dy, and ¹⁶⁴Dy. The ground-state rotational bands up through the 8⁺ member were observed in the ¹⁶O experiments. The measured excitation probabilities yield B(E2; I → I ?2) values which are generally in agreement with the rotational predictions except for the 6⁺ → 4⁺ values. In each nucleus, probabilities for exciting the 2⁺, 4⁺, and 6⁺ members of the γ-vibrational band were measured and compared with calculated results. The B (E2; 0⁺ → 2⁺γ) values were measured in experiments involving ⁴He ions. The K^π = 2^? octupole band was observed in each nucleus in addition to 1^? bands in ¹⁶⁰Dy and ¹⁶²Dy. Excitation probabilities were analyzed in an attempt to extract B(E3) values.     

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Total syntheses of (+/-)-beta-erythroidine and (+/-)-8-oxo-beta-erythroidine by an intramolecular Diels-Alder cycloaddition of a 2-amidoacrolein

[reaction: see text] The total syntheses of (+/-)-beta-erythroidine and (+/-)-8-oxo-beta-erythroidine are described. The tetracyclic ring system of the natural products was quickly assembled by a strategy that features a retrocycloaddition/cycloaddition reaction of an amidodioxin, an intramolecular Heck reaction, and a 6pi-electrocyclic ring closure of a dienoic acid.     

Total syntheses of (+/-)-cis-trikentrin A and (+/-)-cis-trikentrin B via electrocyclic ring closures of 2,3-divinylpyrrolines

[Structure: see text] A convergent and versatile strategy for the diastereoselective syntheses of (+/-)-cis-trikentrin A and B in 10 and 12 steps, respectively, from commercially available N-BOC-2-pyrrolidinone is described. The key step in each of the total syntheses is the construction of the central benzene ring via a facile 6pi-electrocyclic ring closure of an appropriately substituted 2,3-divinylpyrroline, in turn, readily available by a Stille coupling reaction.