Thiacalix[4]arene spirodienone was rearranged into the corresponding phenoxathiin-based macrocycle. Alkylation of this inherently chiral system to achieve its immobilization led to a mixture of only two (out of four theoretically possible) stereoisomers. As standard NOE and dynamic NMR experiments did not lead to unambiguous determination of the structures we applied the Residual Dipolar Coupling constant
Treatment of the monospirodienone derivative of thiacalix[4]arene with various acidic agents (HCl and HBr) results in rearrangement of the thiacalixarene skeleton leading to the formation of a phenoxanthiin derivative in high yields (up to 80%). The structure of the unexpected product is confirmed using 1H and 13C NMR spectroscopy, and X-ray crystallography.
用各种酸性试剂(HCl和HBr)处理噻菌灵[4]芳烃的单螺二烯酮衍生物会导致噻菌灵的骨架重排,从而导致高产(最高80%)的苯氧黄嘌呤衍生物的形成。意外产物的结构使用1 H和13 C NMR光谱法和X射线晶体学确认。
Structure elucidation of phenoxathiin-based thiacalix[4]arene conformations using NOE and RDC data
conformational outcome of the reaction could not be unambiguously assigned using standard NMR techniques, the method of ResidualDipolarCoupling constants (RDCs) was applied. The measuring of an anisotropic through-space dipole-dipole interactions in the lyotropic liquidcrystalline alignment medium (PELG, poly-γ-ethyl-l-glutamate, and PBLG, poly-γ-benzyl-l-glutamate) enabled the assignment of the individual
bearing one sulfoxidegroup and three sulfonyl groups were found to exhibit unexpected stereochemical preferences of the sulfoxidegroup during transformations. The sulfoxide moiety is always pointing out of the cavity (SO out), while the opposite (SO in) configuration was never obtained by direct oxidation. In order to achieve full oxidation to sulfone, the configuration of the sulfoxidegroup must first
基于吩恶硫因的大环化合物代表了一种固有的手性结构单元,可以从起始的硫杂杯[4]芳烃分两步获得。发现带有一个亚砜基和三个磺酰基的氧化衍生物在转化过程中表现出意想不到的亚砜基立体化学偏好。亚砜部分总是指向腔外 (S O out ),而相反 (S O in) 配置从未通过直接氧化获得。为了实现对砜的完全氧化,必须在最终氧化发生之前首先通过光化学反转改变亚砜基团的构型。使用实验(NMR 和单晶 X 射线分析)和理论(DFT)方法相结合的方法研究了硫杂杯芳烃系列中亚砜基团的立体突变现象。
Chemoselective oxidation of phenoxathiin-based thiacalix[4]arene and the stereoselective alkylation of products
an excess of the oxidation agent, systems bearing four sulfonyl groups or three sulfonyl and one sulfoxide group are available in high yields, depending on the reaction conditions. Although four different conformations can be obtained, the alkylation with various alkylating agents led stereoselectively to derivatives being immobilized in the partial cone conformation. The structure of products was assigned