Synthesis and NMR spectroscopic conformational analysis of esters of 4-hydroxy-cyclohexanone—the more polar the molecule the more stable the axial conformer
synthesized and the conformational equilibria studied by 1H and 13C NMR spectroscopy at 103 K and at 295 K, respectively. The geometry of optimized structures of the axial/equatorial chair conformers was computed at the ab initio MO and DFT levels of theory. Only one preferred conformation was obtained for the axial and the equatorial conformer as well. When comparing the conformational equilibria of the
Nanoscale Molecular Rods with a New Building Block for Solubility Enhancement
作者:Pablo Wessig、Kristian Möllnitz
DOI:10.1021/jo800341k
日期:2008.6.1
A new buildingblock bearing a [1,3]dioxolo[4,5-f][1,3]benzodioxole core was developed to enhance the solubility of molecular rods by lateral alkyl chains. On incorporation in molecular rods with oligospiroketal structure, the straight geometry is retained, which was concluded from the X-ray crystal structure analysis of one of the rods. The determination of the solubility of a collection of rods bearing
开发了一种新的带有[1,3] dioxolo [4,5- f ] [1,3]苯并二恶唑核的结构单元,以通过侧链烷基链增强分子棒的溶解性。在掺入具有低螺缩酮结构的分子棒中时,保留了直的几何形状,这是根据其中一根棒的X射线晶体结构分析得出的结论。确定带有该结构单元的棒的集合的溶解度表明,丁基已经有效地阻碍了棒的聚集,因此导致溶解度的显着提高。哌啶环位于杆的末端,这为通用功能化提供了机会。因此,Ñ,Ñ制备了“-双(叠氮乙酰基)-官能化的棒”,该棒可以通过“点击”反应引发的刚性连接。
A modular approach for the synthesis of molecular rods based on oligospiroketals has been developed. The strategy relies on different terminal and intermediate segments, which are joined by ketal formation between ketones and diols. For this purpose it was necessary to develop a new ketalization method to circumvent some problems related with the established methods. The terminal segments are either
作者:Jason Poulin、Christiane M. Grisé-Bard、Louis Barriault
DOI:10.1002/anie.201108779
日期:2012.2.27
Two key reactions in a rapid assembly of the tricyclic core of vinigrol are a stereoselective Claisen rearrangement and an intramolecular Diels–Alder reaction. The method paves the way for a total synthesis of this synthetically challenging and biologically interesting natural product.
on an extension of the previously established concept of oligospiroketal (OSK) rods by replacing a part or all ketal moieties by thioketals leading to oligospirothioketal (OSTK) rods. In this way, some crucial problems arising from the reversible formation of ketals are circumvented. Furthermore, the stability of the rods toward hydrolysis is considerably improved. To successfully implement this concept