Synthesis of cyclopentadienyltricarbonylrhenium substituted benzhydryl species and oestrogen receptor binding properties

Abstract

6-(4-Methoxyphenyl)fulvene has been efficiently engaged in a process implying nucleophilic attack of methyllithium followed by a transmetallation reaction in the presence of different organorhenium sources {XRe(CO) 5 : X = Cl, Br, OTf; BrRe(CH 3 CN) 2 (CO) 3 , [BrRe(CO) 3 THF] 2 } to afford the corresponding cyclopentadienyltricarbonylrhenium-substituted compound. This study allowed us to determine the best complex for that transformation, and similar reaction conditions were used with success to provide new potential radiopharmaceuticals in the cold series. One of these compounds [the (4,4 -dihydroxybenzhydryl)cyclopentadienyltricarbonylrhenium] displays a good recognition for the α form of the oestrogen receptor.

Recent Advances in the Chemistry of Pentafulvenes

“…The formation of lithium cyclopentadienyl reagents obtained from the reduction of fulvenes with LiAlH 4 has been known for a long time. , Even though this approach was mainly used for the preparation of cyclopentadienes after workup, some transmetalation reactions with FeCl 2 or ReBr­(CO) 3 were also reported. , Primary lithium alkyl reagents ( n -BuLi, i -BuLi) have also been successfully employed for the reduction of fulvenes. , This transformation was proposed to proceed via a β-hydride mechanism. The LiCp salts resulting from the reduction of unsymmetrically 6,6-disubstituted fulvenes allowed the synthesis of diastereomerically pure zirconocene complexes for polymerization catalysis after transmetalation and fractional crystallization.…”

“…These complexes exhibited high cytotoxicity, which may arise from the stabilization of mono- or dications through intramolecular coordination from the N , N -dimethylamino groups . Jaouen used this approach for the synthesis of Cp ligands containing steroid groups, which were employed for the synthesis of nonradioactive Re complexes …”

“…14,15 Even though this approach was mainly used for the preparation of cyclopentadienes after workup, some transmetalation reactions with FeCl 2 or ReBr(CO) 3 were also reported. 231,232 Primary lithium alkyl reagents (n-BuLi, i-BuLi) have also been successfully employed for the reduction of fulvenes. 233,234 This transformation was proposed to proceed via a β-hydride mechanism.…”

“…225 Jaouen used this approach for the synthesis of Cp ligands containing steroid groups, which were employed for the synthesis of nonradioactive Re complexes. 231 The addition of Li-indenyl or -fluorenyl compounds onto fulvenes has been developed as a straightforward methodology toward C1 bridged ansa ligands. After double deprotonation with n-BuLi and reaction with ZrCl 4 , C1-symmetric ansa zirconocene dichloride complexes were obtained that display excellent properties in propylene polymerization.…”

Synthesis of Rhenium Carbonyl Complexes Bearing Substituted Pyrrolyl Ligands

“…Thus, pyrrole and simple monoor dicoordinating alkyl-or phenyl-substituted pyrroles were reacted according to the reaction conditions encountered in the cyclopentadienyl series, with dirhenium decacarbonyl under neutral conditions 12 or bromorhenium pentacarbonyl and its derivatives (BrRe(CO) 3 (CH 3 CN) 2 , [BrRe(CO) 3 (THF)] 2 ) under basic conditions. 13 Despite great effort and a thorough screening of reaction conditions (nature of the solvents and bases, modification of concentrations and temperatures), we were not able to isolate any desired products. The reason for this failure could be explained by a poorer σ-donor character of the pyrrolyl ring compared to that of the cyclopentadienyl ring which was studied in the manganese series.…”