9-Methyl-cis-decalin-1,3-dion: Stereochemische Untersuchungen an 9-Methyl-cis-decalin-Derivaten. 5. Mitteilung über cyclische β-Diketone

The synthesis and the spectral properties of the hitherto unknown 9-methyl-cis-decalin-1,3-dione ( 16 ) are described. The keto-enol equilibrium of 16 in various solvents was determined by NMR. spectroscopy. The configuration and conformation of a large number of intermediates and derivatives were determined.     

Autumnariol und Autumnariniol,zwei neue Dibenzo-α-pyrone aus Eucomis autumnalis Graeb. Nachweis einer Fernkopplung über sechs Bindungen in den magnetischen Protonenresonanz - Spektren

From bulbs of Eucomis autumnalis Graeb (Liliaceae) autumnariol ( 1 ) and autumnariniol ( 4 ), two new substituted dibenzo-α-pyrones have been isolated. Their structures have been determined mainly using spectroscopic techniques. In the NMR. spectra of 1 and 4 and related model compounds an unusuallong-range coupling over six bonds has been demonstrated.     

Approaches to the synthesis of cytochalasans. Part 5. Studies on the selectivity of the Diels-Alder reaction leading to the tetrahydroiso-indolinone sub-unit

The stereo- and regiochemical course in the [2+4]cycloaddition of the chiral alkylidene malonic ester 1 to selected derivatives of (2E, 4E)-4-methyl-2, 4-hexadien-l-ol ( 2 ) and (2E, 4E)-4-methyl-2, 4-hexadien-l-al ( 12 ) has been investigated. The results are discussed on the basis of semiquantitative PMO theory.     

Isolation of 2'-dehydroverrucarin A as metabolite of Myrothecium roridum Tode ex Fr.,species type by Fries. Verrucarin and roridin, 13

From cultures of Myrothecium roridum TODE ex FRIES 2′-dehydroverrucarin ( 1 ) was isolated. 1 is a genuin metabolite of the micro-organism.     

37-element solar adaptive optics for 26-cm solar fine structure telescope at Yunnan Astronomical Observatory

A 37-element solar adaptive optics （AO） system was built and installed at the 26-cm solar fine structure telescope of Yunnan Astronomical Observatory. The AO system is composed of a fine tracking loop with a tip/tilt mirror and a correlation tracker, a high-order correction loop with a 37-element deformable mirror, a correlating Shack-Hartmann wavefront sensor based on the absolute difference algorithm, and a real time controller. The system was completed on Sep. 28, 2009 and was used to obtain AO-corrected high-resolution solar images. The contrast and resolution of the images are clearly improved after wavefront correction by AO. To the best of out knowledge, this system is the first solar AO system in China.     

Preparation, crystallographic characterization and theoretical study of two isomers of C70(CF3)12

Two isomers of C70(CF3)12 have been isolated from a mixture obtained by trifluoromethylation of C70 with CF3I; their molecular structures determined by X-ray crystallography are in good agreement with the results of theoretical DFT calculations for the most stable C70(CF3)12 isomers.     

Absolute calibration of Hartmann-Shack wavefront sensor by spherical wavefronts

A method for absolute calibration of Hartmann-Shack wavefront sensor (HSWFS), in which the wavefront differences of several spherical wavefronts are used to determine parameters of HSWFS, is proposed in this paper. The calibration method is introduced and the experiment results and error analysis are presented. Across a pupil with diameter of 2.6 mm, a lenslet array of 20 × 20 sub-apertures with square configuration, and focal length 4 mm, is used to sample the incident wave. The results indicate the uncertainty of the Hartmann-Shack wavefront sensor calibrated by the proposed method, is improved to less than λ/60 PV value and λ/500 RMS value (λ = 635 nm) with modal reconstruction method. Furthermore, the factors affected the results are analyzed. The error analysis suggested that the influences of the factors on the accuracy of reconstruction can be controlled to an accept level.     

Dimerisation of Dipiperidinoacetylene: Convenient Access to Tetraamino-1,3-Cyclobutadiene and Tetraamino-1,2-Cyclobutadiene Metal Complexes

The reaction of 1,2-dipiperidinoacetylene ( 1 ) with 0.5 equivalents of SnCl₂ or GeCl₂⋅dioxane afforded the 1,2,3,4-tetrapiperidino-1,3-cyclobutadiene tin and germanium dichloride complexes 2 a and 2 b , respectively. A competing redox reaction was observed with excess amounts of SnCl₂, which produced a tetrapiperidinocyclobutadiene dication with two trichlorostannate(II) counterions. Heating neat 1 to 110 °C for 16 h cleanly produced the dimer 1,3,4,4-tetrapiperidino-3-buten-1-yne ( 3 ); its reaction with stoichiometric amounts of SnCl₂ or GeCl₂⋅dioxane furnished the 1,3,4,4-tetrapiperidino-1,2-cyclobutadiene tin and germanium dichloride complexes 4 a and 4 b , respectively. Transition-metal complexes containing this novel four-membered cyclic bent allene (CBA) ligand were prepared by reaction of 3 with [(tht)AuCl], [RhCl(CO)₂]₂, and [(Me₃N)W(CO)₅] to form [(CBA)AuCl] ( 5 ), [(CBA)RhCl(CO)₂] ( 6 ), and [(CBA)W(CO)₅] ( 7 ). The molecular structures of all compounds 2 – 7 were determined by X-ray diffraction analyses, and density functional theory (DFT) calculations were carried out to rationalise the formation of 3 and 4 a .