Molecular crystals with moving parts: Synthesis, characterization, and crystal packing of molecular gyroscopes with methyl-substituted triptycyl frames
Molecular crystals with moving parts: Synthesis, characterization, and crystal packing of molecular gyroscopes with methyl-substituted triptycyl frames
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DOI：
10.1021/jo035517i
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发表时间：
2004-03-05
影响因子：
3.6
通讯作者：
Garcia-Garibay, MA
中科院分区：
文献类型：
--
作者：
Godinez, CE;Zepeda, G;Garcia-Garibay, MA
我们报告了一个高度收敛的合成制备的分子陀螺仪组成的对亚苯基转子连接的三键甲基取代的triptycene作为枢轴和封装框架。以2，3-二甲基-1，3-丁二烯为原料，通过Diels-Alder环加成和Pd（0）催化偶联反应合成了1，4-双[2-（2，3，6，7，12，1,3-六甲基-10-烷基-9-三丁酰基）乙炔基]苯。合成中的主要挑战在于通过9-炔基-2，3，6，7-四甲基蒽与苯炔的Diels-Alder反应制备9-炔基三蝶烯。这些反应的化学产率和区域选择性受到蒽核C10取代基的空间效应和电子效应的强烈影响。利用甲基、丙基和苯基取代的蒽完成了相应分子陀螺仪的合成，并通过单晶X射线衍射分析确定了其固态结构。对这些结果的检查表明，正如预期的那样，庞大的三蝶基基团促进结晶基序，从而在亚苯基转子周围产生更多的自由体积，以促进固态下的快速陀螺运动。
We report a highly convergent synthesis for the preparation of molecular gyroscopes consisting of para-phenylene rotors linked by triple bonds to methyl-substituted triptycenes acting as pivots and encapsulating frames. The desired 1,4-bis[2-(2,3,6,7,12,13-hexamethyl-10-alkyl-9-triptycyl)ethynyl] benzenes were prepared from 2,3-dimethyl-1,3-butadiene using Diels-Alder cycloadditions and Pd(0)-catalyzed coupling as the key reactions. The main challenge in the synthesis came about in the preparation of 9-alkynyl-triptycenes by Diels-Alder reaction of benzynes and 9-alkynyl-2,3,6,7-tetramethylanthracenes. These reactions occurred with chemical yields and regioselectivities that were strongly influenced by steric and electronic effects of substituents at C 10 of the anthracene core. Anthracenes with methyl, propyl, and phenyl substituents were utilized to complete the synthesis of their corresponding molecular gyroscopes, and their solid-state structures were determined by single-crystal X-ray diffraction analysis. Examination of these results indicated that, as expected, the bulky triptycyl groups encourage crystallization motifs that create more free volume around the phenylene rotor, as needed to facilitate fast gyroscopic motion in the solid state.