Regioselective synthesis of thiophene fused sultam derivatives via iodocyclization approach and their application towards triazole linker

An efficient regioselective synthesis of 4-iodo-2,3-disubstituted-2H-thieno[3,2-e][1,2]thiazine-1,1-dioxide derivatives via iodocyclization approach using iodine under mild reaction condition described herein. This coupling–iodocyclization strategy tolerated a variety of functional groups such as alkyl, cycloalkyl, phenyl producing the six-membered heterocyclic ring selectively. The resulting 4-iodo-2,3-disubstituted-2H-thieno[3,2-e][1,2]thiazine-1,1-dioxide was coupled with a variety of boronic acids (Suzuki coupling) and activated alkenes (Heck coupling). The iodo group was utilized for Sonogashira coupling followed by efficient transformation to azido precursor, which was used for the synthesis of various thieno-sultam linked with triazole.     

Ring opening of epoxides with alcohols using Fe(Cp)2BF4 as catalyst

Fe(Cp)₂BF₄ is an efficient catalyst for the alcoholysis of aromatic, aliphatic, and cyclic epoxides giving excellent yields of the corresponding β-alkoxy alcohols under ambient conditions. The methanolysis of styrene oxide using Fe(Cp)₂BF₄ as a catalyst (5 mol %) gave excellent yield of 2-methoxy-2-phenylethanol with complete regio-selectivity. The ring opening of cyclic epoxides gave 77–97% yields of trans-β-methoxy alcohols, in 0.5–6 h. The use of 1,2-epoxyhexane and 1,2-epoxydodecane as substrates gave both regioisomers in excellent yields. The first order rate of reaction with respect to catalyst was observed for the kinetics of ring opening of 1,2-epoxyhexane with methanol.     

Formal and total synthesis of (±)-cycloclavine

A ring fragmentation and intramolecular azomethine ylide 1,3-dipolar cycloaddition sequence of reactions was successfully used in the preparation of a known (±)-cycloclavine precursor in good overall yield. Results of efforts to incorporate the tetrasubstituted cyclopropane ring present in cycloclavine are also discussed.     

A practical and efficient synthesis of 6-carboalkoxy-13-cycloalkyl-5H-indolo[2,1-a][2]benzazepine-10-carboxylic acid derivatives

A convenient and practical synthesis of 6-carboalkoxy-13-cycloalkyl-5H-indolo[2,1-a][2]benzazepine-10-carboxylic acid derivatives (6) has been developed. The key step in the synthesis utilizes an intramolecular tandem reaction sequence of a Michael addition followed by a Horner–Wadsworth–Emmons (HWE) olefination reaction between hemi-aminal 11 and methyl 2-(dimethoxyphosphoryl)acrylate 12. The ring construction occurred efficiently and purification of the products 6 was straightforward. The C-10 methyl ester of 6a was hydrolyzed selectively to the carboxylic acid 13 while the olefin of 6d was converted to the cyclopropane 14 using trimethylsulfoxonium iodide in DMSO in the presence of NaH.     

One-pot synthesis of dihydropyrimidines via eco-friendly phosphorus derivatives catalysis

A straightforward, cost effective and eco-friendly protocol for the Biginelli reaction relying on the use of readily available hypophosphorous acid is presented. The methodology developed displays improvements compared to existing methods, is high-yielding, robust and was applied to a panel of dihydropyrimidines and thio-derivatives with various substituents. Related urea derivatives such as guanidines, benzimidazoles and benzothiazoles also reacted efficiently to afford more complex scaffolds. Thus, this rapid and convenient catalysis allows access to a wide diversity of structures including original biologically relevant heterocycles.     

Successive approximation-like 4-bit full-optical analog-to-digital converter based on Kerr-like nonlinear photonic crystal ring resonators

Implementing of photonic sampling and quantizing analog-to-digital converters (ADCs) enable us to extract a single binary word from optical signals without need for extra electronic assisting parts. This would enormously increase the sampling and quantizing time as well as decreasing the consumed power. To this end, based on the concept of successive approximation method, a 4-bit full-optical ADC that operates using the intensity-dependent Kerr-like nonlinearity in a two dimensional photonic crystal (2DPhC) platform is proposed. The Silicon (Si) nanocrystal is chosen because of the suitable nonlinear material characteristic. An optical limiter is used for the clamping and quantization of each successive levels that represent the ADC bits. In the proposal, an energy efficient optical ADC circuit is implemented by controlling the system parameters such as ring-to-waveguide coupling coefficients, the ring’s nonlinear refractive index, and the ring’s length. The performance of the ADC structure is verified by the simulation using finite difference time domain (FDTD) method.     

Mechanical study on the impact of an effective solvent support-removal methodology for FDM Ultem 9085 parts

The use of support material to produce Fused Deposition Modeling parts is often unavoidable. The support removal task tends to be laborious and time-consuming when no soluble support materials are available, which is the case of the high-performance thermoplastic Ultem™ 9085. This paper investigates the effect of different solvent/solvent mixtures on Ultem’s mechanical properties with the aim to identify a solvent capable of dissolving its support material (a polysulfone) without noticeably damaging the model material. To do so, initial solubility tests have helped narrow the list of solvent candidates. These have been followed by infrared analyses to identify the presence of dissolved polymers in the media, as well as scanning electron microscope micrographs to analyze the surface topography of the treated parts. Finally, tensile and flexural tests have permitted to quantify the change on Ultem’s mechanical properties as a function of the treatment time. Major findings include a reproducible method for softening or eliminating Ultem’s support material with non-significant changes in their mechanical properties. The outcome of this work represents a first step on the lookout for a solution to facilitate the removal of polysulfone and is considered of great interest for the scientific community due to the rise of Ultem as a structural material.     

用于全光缓存的光阈值门理论和实验研究

提出了一种基于光阈值门的全光缓存方案,采用两个非对称的SOA环形腔激光器耦合构成光阈值门,其输出光可以在两种波长上切换,可控制波长转换器实现光包路由,从而将需缓存的数据包路由到缓存端口,避免了复杂的包头处理.建立了光阈值门的理论模型,对10 Gbit/s的光阈值门的动态特性进行了数值模拟和实验研究,实验结果和理论计算结果相符合,实验也表明光阈值门两种输出状态的消光比可达30dB.     

激光陀螺磁灵敏度特性研究

分析、计算了激光陀螺的磁灵敏度特性,并进行了磁灵敏度试验.试验结果及分析表明：在腔体加工准确度不变的情况下,采用合理的设计可以大大降低激光陀螺在某些方向上的磁灵敏度,同时磁试验结果对于设计激光陀螺的磁屏蔽结构具有一定的实用价值.     

双环戊二烯开环歧化聚合反应及合成聚合物性能研究

采用WCl6－ArOH／Et2AlCl（ArOH：2，6-二叔丁基对甲苯酚）催化体系进行了双环戊二烯的开环歧化聚合反应，考察了单体纯度以及催化体系支载化对聚合反应和合成聚合物性能的影响。在极限聚合浓度下，研究了单体与主、助催化剂摩尔比等因素对聚合反应及合成聚合物性能的影响。实验结果表明：单体纯度越高所得聚合物的机械性能越好；催化体系经聚合物支载化后能显著提高催化体系的催化聚合活性及合成聚合物的机械性能。