Unique deuterium exchange reaction in certain substituted ferrocenes

Abstract

Deuterium exchange of certain substituted statistical pattern ; a T+O (q5-f?31) rearrangement mechanism is proposed to account for the novel pattern of ferrocenes (under very mild basic conditions) occurs in only the substituted cyclopentadienyl-ring in non-exchange.

The synthesis and structures of 1,1′-bis(sulfonyl)ferrocene derivatives

“…Slocum and Achermann 34 presented a comprehensive report on N-monosubstituted and N, N-disubstituted sulfonamides, following a 1980 report that examined deuterium exchange on the N,N dimethyl variant. 38 A few years later, a study on a series of β-lactam antibiotics linked to ferrocene via sulfonamide groups was presented by Vâţǎ and coworkers. 39 Fabbrizzi presented a series of reports on cyclams covalently attached to ferrocene 40,41 ; later work by Roglans 42 used the same linking methodology to attach ferrocene to organometallic chelates.…”

Preparation of Cyclopentadienyltricarbonylrhenium Complexes Using a Double Ligand-Transfer Reaction

“…Cyclopentadienyl ring slippage is by no means uncommon . For example, it has been used to explain the nonstatistical deuterium incorporation patterns of certain substituted ferrocenes in refluxing pyridine ), and they rationalized its formation via a variety of ring-slipped intermediates, including 4 and 5 .…”

Efficient synthesis of deuterium-labelled ferrocenes

“…The intensities are in arbitrary units 76.90 ppm. In the present study, the 1 H NMR (CDCl 3 ) spectrum shows a small signal for the remaining undeuterated protons at 4.2 ppm while the 13 C NMR (CDCl 3 ) for compound 2 have a multiplet dominated by a triplet at 67.32 ppm.…”

“…1 H and 13 C NMR spectra were recorded on a 400 MHz NMR (Bruker) spectrometer (400 MHz for 1 H NMR and 100 MHz for 13 C NMR) in deuterochloroform, using TMS as internal standard.…”

“…Slocum et al 13 examined the base-promoted deuterium exchange of several ferrocene systems and reported that some of the electron-withdrawing substituents, particularly acetyl-and 1,1 0 -diacetyl-are capable of activating the ferrocene ring toward the electrophilic deuterium exchange and only the cyclopentadienyl ring bearing the substituent were exchanged in monosubstituted ferrocene. Hence in order to ascertain the influence of electronwithdrawing substituents on the acid-catalysed electrophilic deuterium exchange and to compare with that of electron-donating groups, acetylferrocene 9 and 1,1 0 -diacetylferrocene 11 (Scheme 3) were subjected to acidcatalysed deuterium exchange reactions in a one pot reaction at 1008C for 46 h.…”