Crystal and molecular structure of a crown-bridgedp-t-butyl-calix[4]arene (1:1) pyridine complex. Host-guest interaction model based on molecular mechanics analysis [1]

The crystal and molecular structure of a crownedp-t-butyl-calix[4]arene (1:1) pyridine complex is reported. Colourless transparent prismatic crystals (obtained from pyridine) C₅₄H₇₄O₈·C₅H₅N,a=13.486(4),b=15.193(4),c=16.432(5) Å, =116.44(4)°, space groupP2₁,Z=2,D _calc=1.02g cm^–3, CuK radiation =1.5418 Å (CuK )=4.99 cm^–1. Refinement was carried out using 1702 reflections withI>3(I) toR 0.12. The macrocycle shows a distorted cone conformation which defines an intramolecular apolar cavity whose elliptical aperture is 11.5×8.6 Å calculated as distances between the two opposite central C atoms of the Bu ^t groups. A molecule of pyridine is included in this cavity, whereas the intermolecular cavities of the host lattice remain empty. The influence of the guest molecule on the conformation of the calixarene-crown is discussed. Potential energy calculations are performed in order to understand the nature of the host-guest interactions responsible for the stabilisation of the complex. Evidence for stabilizing CH₃- interactions are obtained from the calculations. Supplementary Data relevant to this article have been deposited with the British Library as supplementary Publication No. SUP 82068 (9 pages).     

Macrocyclic Systems Containing 2,6,9-Trioxabicyclo[3.3.1]-nona-3,7-dienes as Chiral Spacer Groups: Synthesis,Stereochemical Features and Preliminary Complexation Properties

Novel 2:2-macrocycles bearing bridged concave 2,6,9-trioxabicyclo[3.3.1]nona-3,7-dienes as chiral spacer units were obtained by cyclocondensation reaction of the chiral bisacid chloride and the corresponding diols, while use of methylene diamines instead of diols afforded 1:1 macrocycles only. Applying the same, but now template-assisted, experimental procedure to the reaction of the bisacid chloride with triethylene glycol brought about a significant increase in yield as well as a suitable simplification of the work-up during preparation and separation of the corresponding 1:1 as well as 2:2 macrocycles, when compared to results reported previously. HPLC separation on chiral columns revealed the presence of diastereoisomers [R,R(S,S)- and R,S-(meso)-forms] for all 2:2 macrocycles, which was further evidenced by the CD spectrum of one of those species as an example. Preliminary ESI-MS experiments indicated strong complexation abilities of the sulphur-containing ligand towards Ag(I), Cu(II) and Au(III) ions.     

“Rapid and Inexpensive Method for Reduction of Nitroarenes to Anilines”

Nitroarenes are reduced to corresponding anilines in good yields using ferric chloride - Zinc - Dimethyl formamide - water system.     

三桥连双铁(III)配合物[Fe_2(IDB)_2(O)(CH_3CO_2)_2]Cl_2·CH_3OH的晶体结构及其傅立叶变换拉曼光谱(英文)

合成了一种新的三桥连双铁 (III)配合物 [Fe2 (IDB) 2 (O) (CH3CO2 ) 2 ]Cl2 ·CH3OH ,IDB为N ,N’ -di(2’ -benzimidazolylmethyl)imine,利用单晶X射线衍射及其它谱学方法对所合成配合物进行了表征。每个双核单元的两个铁原子均通过一个氧原子和两个醋酸根连接 ,每个铁原子同时还与位于桥氧原子对位的三齿配体IDB重脂肪链上氮原子相结合 ,每个铁 (III)中心为一变形八面体结构。对该新化合物的拉曼光谱进行了研究并对一些谱峰进行了归属     

Synthesen von Hydroxy- sowie Methoxy-dicyano-pseudo-phenafulvenen mit zentraler 1.6-Methano-[10]-annulen-gruppe

Synthesis of pseudophenalenone3 are described starting from 2-acetyl-1.6-methano-[10]-annulene (1) via2 and from the dihydro-pseudophenalenone4 besides the chloro-derivative5. Reaction of acetylhexachloroantimonate6 with3 at low temperatures yields the acetyloxy-pseudophenalenium-hexachloro-antimonate7 which reacts with sodium-malodinitrile and triethylamine to give a mixture of isomers14/15, with dimethylsulfate and sodiumhydroxide to the mixture of isomers16/17.

Herrn Prof. Dr. Drs. h. c. mult.Georg Wittig in Verehrung und dank barer Freundschaft mit herzlichen Wünschen zum 85. Geburtstag am 16. Juni 1982 gewidmet.     

A formal synthesis of (+)-didemniserinolipid B employing a Pd-mediated 6-endo selective alkynediol cycloisomerization

Herein, we describe a concise assembly of central 6,8-dioxabicyclo[3,2,1]octane core of didemniserinolipid by employing a Pd-mediated alkynediol cycloisomerization and a formal total synthesis of didemniserinolipid B.