Bis (2,4,6,8‐cyclononatetraen‐1‐yl)methane

Abstract

Bis (2,4,6,8~yclononatetraen-l-yl)methanes Bis (2,4,6,8-~yclononatetraen-1-y1)methanes (2a-c) have been prepared by reaction of all-cis -cyclononatetraenide with 1,l-dichlorodimethyl ether as well as with carbenium ion precursors 9b and 912. The title compounds 2 are attractive precursors of highly delocalised nonafulvenes of type 3; however, elimination experiments 2-3 failed so far.

Synthetic Attempts towards ‘Aromatic’ Nonafulvenes

“…Some of these problems have already been discussed [12] [25]. They are substantially increased by the thermal instability of cyclononatetraenes 8 as well as of most nonafulvenes 1 which in many cases affords reactions -as well as workup procedures -at temperatures below 0".…”

“…It is well-known that ( Z Z Z E ) d has several nucleophilic centres [24]: nucleophilic attack with C(1) leads to cyclononatetraenes 8, while attack with C(4) to C(7) gives, after rearrangement, bicyclo[6.1 .O]nonatrienes of type 16. In most cases, especially in reactions with delocalized carbenium ions, (ZZ2E)-6 reacts with C( 1) [25] and is, therefore, preferred, due to its higher nucleophilicity compared with (ZZZZ)-6. In reactions of (ZZZE)-6 with bulky electrophiles, however, bicyclo[6.1 .O]nonatrienes 16 are the main products.…”