Tetradehydro-Diels–Alder Reactions of Flexible Arylalkynes via Folding Inside a Molecular Cage
作者:Georgi R. Genov、Hiroki Takezawa、Harumi Hayakawa、Makoto Fujita
DOI:10.1021/jacs.3c06301
日期:2023.8.9
employed substrates allows for efficientencapsulationwithin the host cavity. The rate of thermal cyclization of the encapsulated guest was found to be greatly enhanced, and high product selectivity for an unsymmetrical substrate was observed. The efficiency of this system relies on the precise conformational control of the substrate within the confined space of the host cage.
四氢-狄尔斯-阿尔德 (TDDA) 反应是一种有用的转化,可在单个合成步骤中从简单的线性前体快速组装多环支架。然而,该反应需要仔细的底物设计和苛刻的反应条件,以克服这种转化固有的熵成本。在此,我们报告了自组装 Pd 6 L 4笼内有效的位点选择性 TDDA 转化。尽管尺寸很大,但所使用的基板的灵活性允许在主体腔内进行有效的封装。发现封装客体的热环化速率大大提高,并且观察到对不对称基材的高产物选择性。该系统的效率依赖于宿主笼有限空间内底物的精确构象控制。
Enantioselective Syntheses of Various Chiral Multicyclic Compounds with Quaternary Carbon Stereocenters by Catalytic Intramolecular Cycloaddition
The intramolecular cycloaddition of 1,n-diene-ynes (n = 4-6), where alkyne and alkene moieties are connected by a 1,1-disubstituted alkene, was examined using a chiral rhodium catalyst, and various types of cycloadducts with quaternary carbon stereocenter(s) were obtained in high to excellent enantiomeric excess. In the case of 1,4-diene-ynes, tricyclic, bicyclic, and spirocyclic compounds were obtained depending upon the substituents at the 2-position of the 1,4-diene moiety and those at their alkyne termini. On the other hand, 1,5- and 1,6-diene-ynes gave tricyclic and bicyclic compounds, which included medium-sized ring systems. The mechanistic considerations for different reaction pathways and the synthetic transformation of tricyclic products into functionalized spirocyclic compounds are also described. The reaction of enediynes, where two alkyne moieties are connected by a 1,1-disubstituted alkene, was also examined, and sterically strained tricyclic compounds with two carbon stereocenters were obtained.