Analysis and Improvement of an Anion-Templated Rotaxane Synthesis
摘要:
A series of new rotaxanes with axles different in length was prepared. Following the synthetic protocol utilizing a known anion template effect (Scheme 1), surprisingly low yields in the order of 2 - 5% were obtained (Scheme 3), which furthermore significantly depended on the nature of the stopper (Fig. 1). Variations in the synthetic procedures and computational results from Monte Carlo simulations allowed us to analyze the origin of these findings: The rotaxane wheel 3 acts as a noncovalently bound 'protecting group' for the stopper nucleophile. The protection of the nucleophilic phenolate O-atom depends much on the steric demands of the stoppers (see 2 vs. 10) which induce different conformations of the wheel. Based on this model. an improved synthetic scheme is suggested.
Process for generation of acid and for imaging, and imaging medium for
申请人:Polaroid Corporation
公开号:US05395736A1
公开(公告)日:1995-03-07
Acid can be generated by exposing a superacid precursor to actinic radiation effective to generate superacid from the superacid precursor and heating the superacid in admixture with a secondary acid generator capable of undergoing thermal decomposition to produce a secondary acid. The superacid catalyzes decomposition of the secondary acid generator, thus increasing the quantity of strong acid present in the medium. The resultant secondary acid can be used to effect a color change in an acid-sensitive material, so providing an imaging process.
This report describes the synthesis of a seventeen-membered macrocyclic ring containingligand (L1) by the reaction of 1,8-bis(2-(chloromethyl)phenoxy)octane with selenium powder. The trans-palladium dichloride complex (C1) of the macrocyclic selenium ligand was synthesized from its reaction with the Pd(CH3CN)2Cl2 precursor. The formation of the ligand and complex was authenticated with the help of
本报告描述了通过 1,8-双(2-(氯甲基)苯氧基)辛烷与硒粉的反应合成含有配体 ( L1 )的十七元大环。大环硒配体的反式-二氯化钯络合物( C1 )是通过其与Pd(CH 3 CN) 2 Cl 2前体的反应合成的。借助1 H 和13 C 1等各种分析技术验证了配体和复合物的形成H} NMR、HRMS、FTIR、紫外-可见光谱和元素分析。借助单晶 X 射线衍射验证了配体的结构及其与钯前体的配位模式。该复合物在钯中心周围具有扭曲的方形平面几何形状。新的配体和复合物对空气和湿气不敏感,并且在室温下稳定三个月以上。变温核磁共振数据和计算研究表明钯络合物 ( C1 ) 中的硒反转具有~22.6 kcal mol -1的反转势垒。钯配合物C1用作含二羟基化合物的长烷基链脱羟甲基化的催化剂。通常,两种单独的催化剂用于脱羟甲基化(一种用于醇的氧化,另一种用于醛的脱羰基)。在这里,单一催化剂显示出脱羟甲基化的双重作用,在仅