Ferrocenes ring cleavage

The azetidin-2-one 475 bearing a ferrocene moiety at C-4 undergoes deprotonation to form 2-azetine 599, which undergoes ring cleavage to afford the amide 476 (Scheme 79) <2001JOC8920>. 

The mass spectra of some vinylic ferrocenes have been measured (134) and all show a strong molecular ion peak, and cleavage of the unsubstituted ring usually occurs before fragmentation of the vinyl substituent. 

One of the decomposition products if I and II is ferrocene. This ds viewed as further evidence that these Cp U-R complexes decompose by the intramolecular proton abstraction mechanism as seen in the "monomer organoactinide (27, 36). The mass spectrum of I reveals that a cyclopentadienyl ring is lost first (presumably from Cp U) in preference to cleavage of the U-C a bond. 

In the arylative ring opening of 3-substituted cyclobutanols, enantioselective cleavage of the C-C bond has been achieved by using a palladium catalyst with a chiral ligand [33-35]. Particularly, the use of the chiral ferrocene-containing N,P-bidentate ligand shown in Eq. 17 leads to excellent enantioselectivity. 

Photo-induced additions of ferrocene to electron-deficient alkynes, giving 1-ferrocenylalkenes, photo-ethoxycarbonylation of ferrocene derivatives ( v-CCU-EtOH), and electrochemically-initiated additions of alkyl radicals (from RCOg ) to ferricenium cation have been reported. Electrochemical reductive cleavage of the ring-metal bonds in carbonyl-substituted ferrocenes has been achieved using polarographic methods. ... 

---