ISSN:
0947-3440
Keywords:
1,3,4-Oxadiazoles
;
Dendrimers
;
Stacking interactions
;
Carbonylations, of tetrazoles and acid hydrazides
;
Chemistry
;
Organic Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
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 1H-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.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/jlac.199719970725
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