Forty-six- and fifty-membered endo-functionalizedmacrocycles were obtained by template syntheses with new stiff tetracyclic tetraols 10 and 11. Reaction of dialkenylatedboronic acids 1 with template molecules 10 and 11 generated preorganized bisboronic esters 18 and 19, which were cyclized by ring-closing olefin metathesis. Resulting bimacrocycles 20 and 21 were obtained in ca. 60 % yield when alkenyl
Bimacrocyclic Pyridines and 1,8-Naphthyridines: Basicities and Application in Base Catalysis
作者:Ulrich Lüning、Timo Liebig
DOI:10.1055/s-0034-1378384
日期:——
can be coupled with 2,6-bis(alkenyloxy) substituted areneboronic acids. The resulting tetraenes are then cyclized by ring-closing metathesis to give bimacrocyclic concave pyridines or concave 1,8-naphthyridines. The relative basicity of the concave N-heterocycles was measured and their activity and selectivity was tested in the base-catalyzed addition of alcohols to diphenylketene. Di-α-substituted
Macrocycle synthesis by trimerization of boronic acids around a hexaol template, and recognition of polyols by resulting macrocyclic oligoboronic acids
作者:Dennis Stoltenberg、Ulrich Lüning
DOI:10.1039/c3ob40554k
日期:——
liberates the template and generates a macrocycle with three boronicacid functionalities in endo-orientation. Due to this preorganization, macrocycles with boronicacids in endo-positions are good receptors for polyols. The binding of carbohydrates such as fructose was compared with the uptake of the respective templates into macrocycles with two or three boronicacids in endo-orientation.