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Nonafulvalen: Synthese durch oxidative Kupplung von Cyclononatetraenid und Valenzisomerisierung
Author(s) -
Escher André,
Neuenschwander Markus,
Engel Peter
Publication year - 1987
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19870700620
Subject(s) - chemistry , deprotonation , isomerization , oxidative coupling of methane , valence (chemistry) , medicinal chemistry , oxidative phosphorylation , stereochemistry , computational chemistry , catalysis , organic chemistry , ion , biochemistry
Nonafulvalene: Synthesis by Oxidative Coupling of Cyclononatetraenide and Valence Isomerisation Following a general strategy ( Scheme 2 ) for the synthesis of fulvalenes by oxidative coupling of Hückel anions, the synthesis of nonafulvalene ( 1 ), has been realised ( Scheme 3 ). The most tricky step is a twofold deprotonation of bi(cyclononatetraenydl) 3 with K ( t ‐BuO) to give 4 ; it is only possible after equilibration 3⇄3a ; otherwise, deprotonation of one cyclononatetraene unit of 3 followed by oxidative coupling with AgBF 4 gives quater(cyclononatetraenyl) 12 as an isomeric mixture. The reaction of 3 with K gives potassium cct ‐cyclononatetraenide 11 ( M = K; Scheme 5 ) and not the dianion 4 as reported in the literature. Nonafulvalene ( 1 )is extremely reactive due to its very easy valence isomerisation to geve an isomeric mixture of tetrahydro‐dibenzopentafulvalenes 13 ( Scheme 4 ). The structure of crystalline isomer ( E‐anti )‐ 13 has been proved by X‐ray analysis.