Formation of alkyne-bridged ferrocenophanes using ring-closing alkyne metathesis on 1,1’-diacetylenic ferrocenes

Abstract

Novel alkyne-bridged ferrocenophanes [fc{CO2(CH2)nC≡}2] (2a: n = 2; 2b: n = 3) were synthesized from the corresponding terminal diacetylenic ferrocenes [fc{CO2(CH2)nC≡CH}2] (1a: n = 2; 1b: n = 3) through ring-closing alkyne metathesis (RCAM) utilizing the highly effective molybdenum catalyst [MesC≡Mo{OC(CF3)2CH3}3] (MoF6; Mes = 2,4,6-trimethylphenyl). The metathesis reaction occurs in short time with high yields whilst giving full conversion of the terminal alkynes. Furthermore, the solvent-dependant reactivity of 2a towards Ag(SbF6) is investigated, leading to oxidation and formation of the ferrocenium hexafluoroantimonate 4 in dichloromethane, whereas the silver(I) coordination polymer 5 was isolated from THF solution.

Organometallic Chemistry of Transition Metal Alkylidyne Complexes Centered at Metathesis Reactions

“…As a result, limited catalysts are available for terminal alkyne metathesis. The most successful systems include Mo­(CC 6 H 4 - p -OMe)­(OSiPh 3 ) 3 ( 38b ), ,− W­(CMes)­{OCMe 2 (CF 3 )} 3 ( 47b ), and Mo­(CMes)­{OCMe­(CF 3 ) 2 } 3 ( 36a ), ,,, which can promote homometathesis, cross-metathesis, and ring closing metathesis of terminal alkynes. Complexes such as W 2 (OCMe 2 CH 2 OMe) 6 and W­(C t Bu)­(O t Bu) 3 ( 45a ) with or without quinuclidine have also been examined for homometathesis of terminal alkynes.…”