Preparation and Characterization of New C2‐ and C1‐Symmetric Nitrogen,Oxygen, Phosphorous,and Sulfur Derivatives and Analogs of TADDOL. Part I

The chloro alcohols 4 – 6 derived from TADDOLs (=α,α,α′,α′‐tetraaryl‐1,3‐dioxolan‐4,5‐dimethanols) are used to prepare corresponding sulfanyl alcohols, ethers, and amines (Scheme 1 and Table 1). The dithiol analog of TADDOL and derivatives thereof, 45 – 49 , were also synthesized. The crystal structures of 16 representatives of this series of compounds are reported (Figs. 1–3 and Scheme 2). The thiols were employed in Cu‐catalyzed enantioselective conjugate additions of Grignard reagents to cyclic enones, with cycloheptenone giving the best results (er up to 94 : 6). The enantioselectivity reverses from Si‐addition with the sulfanyl alcohol to Re‐addition with the alkoxy or dimethylamino thiols (Table 4). Cu^I‐Thiolates, 50 – 53 , could be isolated in up to 84% yield (Scheme 2) and were shown to have tetranuclear structures in the gas phase (by ESI‐MS), in solution (CH₂Cl₂, THF; by vapor‐pressure osmometry and by NMR pulsed‐gradient diffusion measurements; Table 5), and in the solid state (X‐ray crystal structures in Scheme 2). The Cu complex 50 of the sulfanyl alcohol is stable in air and in the presence of weak aqueous acid, and it is a highly active catalyst (0.5 mol‐%) for the 1,4‐additions, leading to the same enantio‐ and regioselectivities observed with the in situ generated catalyst (6.5 mol‐%; Scheme 3). Since the reaction mixtures contain additional metal salts (MgX₂, LiX) it is not possible at this stage, to propose a mechanistic model for the conjugate additions.     

New Labdane‐Type Diterpenoids from Leonurus heterophyllus

Chemical investigation of the aerial part of Leonurus heterophyllus led to the isolation and characterization of the seven labdane‐type diterpenoids 1 – 7 , including six new ones, 1 – 6 . Compounds 4 and 5 were isolated as a C(15) epimer pair. The determination of the structures and relative configurations of the new compounds were mainly based on 1D‐ and 2D‐NMR spectroscopic methods, and comparison of their NMR data with related compounds. The structure of compound 7 was confirmed by X‐ray crystallographic analysis.     

A New Alkylation Method for Heptalene‐4,5‐dicarboxylates and of One of Their Pseudoester Forms

Dimethyl heptalene‐4,5‐dicarboxylates

1 The locants of heptalene itself are maintained throughout the whole work. See footnote 4 in [1] for reasoning.

undergo preferentially a Michael addition reaction at C(3) with α‐lithiated alkyl phenyl sulfones at temperatures below ?50°, leading to corresponding cis‐configured 3,4‐dihydroheptalene‐4,5‐dicarboxylates (cf. Table 1, Schemes 3 and 4). The corresponding heptalenofuran‐1‐one‐type pseudoesters of dimethyl heptalene‐4,5‐dicarboxylates (Scheme 5) react with [(phenylsulfonyl)methyl]lithium almost exclusively at C(1) of the furanone group (Scheme 6). In contrast to this expected behavior, the uptake of 1‐[phenylsulfonyl)ethyl]lithium occurs at C(5) of the heptalenofuran‐1‐ones as long as they carry a Me group at C(11) (Schemes 6 and 7). The 1,4‐ as well as the 1,6‐addition products eliminate, on treatment with MeONa/MeOH in THF, benzenesulfinate, thus leading to 3‐ and 4‐alkylated dimethyl heptalene‐4,5‐dicarboxylates, respectively (Schemes 8–13). The configuration of the addition reaction of the nucleophiles to the inherently chiral heptalenes is discussed in detail (cf. Schemes 14–19) on the basis of a number of X‐ray crystal‐structure determinations as well as by studies of the temperature‐dependence of the ¹H‐NMR spectra of the addition products.     

声学理论在超短基线跟踪自治水下机器人中的应用

对超短基线定位系统的有效跟踪范围问题进行了研究,将射线声学基本理论和声纳方程相结合,提出一种确定超短基线定位系统在试验现场跟踪范围的有效方法。利用射线方程确定跟踪范围的上边界;利用声纳方程确定跟踪范围的下边界,上、下两个边界所围区域确定有效跟踪范围。湖上和海上试验证明了方法的有效性,提高了超短基线定位系统跟踪自治水下机器人自动航行的安全性和可靠性。。     

Rooms with a view: A novel approach to iterated multidimensional wave conversion

Ray tracing in the presence of linear mode conversion leads to a ‘splitting’ of an incoming ray into two outgoing rays. When the rays are confined to a cavity, the rays can re-enter the conversion region many times, leading to iterated conversion. In this paper, we present new methods for the analysis of this problem. These involve a shift from local to global methods of analysis, and a shift in emphasis from the study of ray evolution in the dispersion surface to the study of the iterated dynamics of rays crossing the conversion surface. The analytical methods are quite general and can be applied in phase spaces of arbitrary dimension. In two spatial dimensions, (x, y), i.e. with a four-dimensional ray space, (x, y, k_x, k_y), rays are confined to three-dimensional regions called rooms, with one room for each wave type. In these rooms the rays do not cross, but when they intersect the conversion surface a family of converted rays is produced in the other room. The use of rooms allows a full view of the phase space dynamics of the iterated conversion of ray families. A simple two-dimensional model, inspired by the Budden resonance model, is presented as an example of these ideas.     

Growth of KCl crystal by Czochralski method and influence of nanodiamond impurity on its hardness and optical properties

KCl alkali halide crystal with different nanodiamond impurity was grown by Czochralski method. X‐Ray diffraction of the outcome samples reveals that they are still single crystal. Also crystal hardness observation reveals that the hardness of KCl single crystal has been increased by adding different percentage of nanodiamond impurity. In addition, the study of FTIR spectrums of the pure and doped crystals represents that the KCl optical properties has not changed.