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Stereoselective Formation of Triphenylene Ketals
Author(s) -
Boshta Nader M.,
Bomkamp Martin,
Schnakenburg Gregor,
Waldvogel Siegfried R.
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200903249
Subject(s) - triphenylene , chemistry , electrophile , stereoselectivity , isomerization , oxidizing agent , reagent , catechol , combinatorial chemistry , organic chemistry , catalysis , molecule
The oxidative trimerization of catechol ketals by MoCl 5 or MoCl 5 /TiCl 4 mixtures leads preferentially to the all ‐ syn stereoisomer of the corresponding triphenylene ketal. The concomitant metal salts of the oxidative coupling most probably form a multinuclear template that directs the diastereoselectivity in a subsequent isomerization step under electrophilic conditions. Several functionalities can serve as coordination sites for the multinuclear metal chloro clusters. Suitable functional groups have to be stable towards the strong electrophilic and oxidizing conditions. Therefore, esters, nitriles, nitro derivatives, triazoles, and pyridines are successfully employed. Based on the flexibility and size of the substrate, different reagent mixtures lead to the stereoselective formation of the all ‐ syn derivatives.