Synthese und NMR‐Spektren von Nonafulven sowie Vergleich mit 10‐Phenylnonafulven

Synthesis and NMR Spectra of Nonafulvene and Comparison with 10-Phenylnonafulvene Experimental procedures for the reaction of cis,cis,cis,trans-cyclononatetraenide (ccct-CNT−; see 4) with bromomethyl acetate (1a, R = H, X = Br) to give (cyclononatetraenyl)methyl acetate (5a; 84% yield) as well as for the base-induced elimination of HOAc from 5a to give nonafulvene (6a; 44% yield) are described. Spectroscopic as well as chemical evidence for 6a and 6b is presented. An approximate high-field-NMR analysis of 6a and 6b has been completed. The results are in favour of a fast interconversion of the type 6A⇄6B (Scheme 4), and supported by the MNDO-optimised geometry of 6a. The first X-ray analysis of a cyclononatetraene (i.e. of 5b) has been accomplished: 5b is a polyolefinic molecule with largely alternating bond lengths and with a nine-membered ring deviating strongly from planarity.