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Synthesis and Self‐Association of First‐Generation 1,3,4‐Oxadiazole‐Containing Dendrimers
Author(s) -
Kraft Arno
Publication year - 1997
Publication title -
liebigs annalen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.825
H-Index - 155
eISSN - 1099-0690
pISSN - 0947-3440
DOI - 10.1002/jlac.199719970725
Subject(s) - chemistry , dendrimer , oxadiazole , aryl , solvophobic , carbonylation , vapor pressure osmometry , carbon monoxide , polymer chemistry , catalysis , organic chemistry , combinatorial chemistry , molecule , vapor pressure , alkyl
Two 1,3,4‐oxadiazole‐containing dendrimers, 14 and 15 , have been prepared employing a palladium‐catalyzed carbonylation reaction as the key step of the synthesis. In order to shorten the reaction sequence, a new oxadiazole synthesis has been developed based on the coupling of aryl iodides with aryl tetrazoles in the presence of a Pd(0) catalyst and carbon monoxide, and has been applied to the preparation of dendrimer 14 . Both new dendrimers are highly soluble in chlorinated solvents, but 14 , with fewer solubilizing tert ‐butyl groups at its periphery, self‐associates in solution by π‐π interactions and possibly due to solvophobic effects. Considerable upfield shifts of the 1 H‐NMR signals of the protons in the centre of the molecule indicate the formation of π‐stacks in solution. Vapour‐pressure osmometry studies allow a degree of association of ⩾3 to be estimated.