ChemInform Abstract: Increasing the Structural Span of Alkyne Metathesis.

Abstract

Several new catalysts for alkyne metathesis, e.g. MMC, are introduced.

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

“…However, this behaviour is in good agreement with other literature examples that state the metathesis of internal propargylic systems being particularly challenging. 13,96,97 As the [10]ferrocenophane 2a can be obtained reliably and selectively from the RCAM reaction, additional electrochemical and chemical studies were performed on this compound. To resolve the barrier for the chemical oxidation, the cyclovoltammogram of 2a was recorded in DCM ( Figure 7).…”

“…Molybdenum alkylidyne complex I with siloxide ligands (X=OSiPh3) 10,11 is widely used in natural product synthesis, predominantly through ring-closing alkyne metathesis (RCAM). [12][13][14][15][16][17][18][19][20] The metathesis of conjugated diynes (DYCM) is promoted by the benzylidyne tungsten complex II with silanolate ligands (X = OSi(OtBu)3); 21,22 this catalyst is also active in classical alkyne metathesis. 23 Complexes III with chelating phenoxide ligands [24][25][26][27] are mostly applied in supramolecular chemistry, [28][29][30][31][32] used for instance in the preparation of aryleneethynylene macrocycles and cages through alkyne metathesis.…”

“…The RCAM of the butynyl system 1a afforded the desired monomeric ferrocenophane 2a in a high yield (93%). The signal for the terminal proton has vanished in the 1 H NMR spectrum, and the13 C NMR spectrum only shows one signal at 79.6 ppm associated with the symmetric C≡C triple bond. The same high yield for compound 2a could be achieved in an identically performed RCAM with a higher substrate concentration of 1a of 21 mM.…”

“…This reactivity could only lately be shown for complex I as well. 13,16,46 Beforehand, the promotion of terminal alkyne metathesis (TAM) proved to be difficult due to several deactivation pathways. [47][48][49][50][51][52][53] Figure 1: Well-defined catalysts for alkyne metathesis.…”