An aryne triggered ring-opening fluorination of cyclic thioethers with potassium fluoride
作者:Rong Fan、Binbin Liu、Tianyu Zheng、Kun Xu、Chen Tan、Tianlong Zeng、Shuaisong Su、Jiajing Tan
DOI:10.1039/c8cc03766c
日期:——
report an aryne triggered ring-opening fluorination protocol of a great variety of saturated sulfur heterocycles. A key factor for the success is the identification of a suitable mediator. Compared to previous methods, this transition-metal free protocol employs low-cost potassium fluoride as the fluorine source. The operational simplicity and mild reaction conditions allow for the rapid synthesis of a
Biocatalytic Desymmetrization of Prochiral 3-Aryl and 3-Arylmethyl Glutaramides: Different Remote Substituent Effect on Catalytic Efficiency and Enantioselectivity
作者:Yu-Fei Ao、Li-Bin Zhang、Qi-Qiang Wang、De-Xian Wang、Mei-Xiang Wang
DOI:10.1002/adsc.201800956
日期:2018.12.3
efficiently afforded 3‐substituted glutaric acid monoamides in up to 95% yield and >99.5% ee. Even far away from the reaction site, the substituents on the aryl still have a significant effect on the catalytic activity and enantioselectivity and different remote substituent effect was observed for the two types of substrates. The synthetic application of biocatalyticdesymmetrization was demonstrated by
Lipophilic cage compounds from 1,7-dioxa-4,10-diazacyclododecane: exceptionally strong ligands for the sodium cation and effective anion activators in non-polar media
作者:Pier Lucio Anelli、Fernando Montanari、Silvio Quici
DOI:10.1039/c39850000132
日期:——
Lipophiliccagecompounds (1) and (2) containing two diaza-crown units (3) form very stable complexes with sodium salts; they allow effectiveactivation of hydrophilic and/or highly electronegative anions in non-polarmedia.
Cylindrical cryptands 2a-c, in which two 1,7-dioxa-4,10-diazacyclododecane rings are connected by two equally substituted propylene bridges, have been obtained in appreciable yields by a ''one-pot'' synthesis. The assembling of the macrotricyclic structure is likely driven by the template effect of metal cations. These compounds, both as free receptors or as complexes, exist as cis and trans diastereoisomers, which do not interconvert and have been separated and characterized by X-ray analysis. The extraction constants (K-e) of cryptands 2 for alkali picrates under CHCl3/H2O and solid/liquid two-phase conditions have been measured by UV-vis spectrophotometry. The complexation behavior of cryptands 2 has been rationalized analyzing the preorganization of binding sites in the minimum energy conformations obtained by molecular mechanics calculations. Minimum energy conformations have been calculated also for the previously reported cryptands 1 and have been compared with those of 2. Results fit reasonably well with those of X-ray structures.
Lipophilic cage ligands containing two tightly connected 1,7-dioxa-4,10-diazacyclododecane rings: synthesis and x-ray structure of a sodium perchlorate complex
作者:Pier Lucio Anelli、Fernando Montanari、Silvio Quici、Gianfranco Ciani、Angelo Sironi