Reactions of Cp2TiMe2 with ferrocene and (ɳ5-Cp)Co(ɳ4-C4Ph4) derived esters and amides: A new route for 1-methylvinyl and methyl ketone derived metal sandwich compounds

• New route for the formation of 1-methylvinyl derived metal sandwich compounds from esters and amides.
• First observation of nucleophilic substitution of methyl groups by Cp2TiMe2.
• An easy access for conversion of metal sandwich derived esters to methyl ketones.

Reactions of Cp2TiMe2, with the ester derivatives of organometallic sandwich compounds (ɳ5-RC5H4)Fe(ɳ5-C5H5) and (ɳ5-RC5H4)Co(ɳ4-C4Ph4) (R=ester groups) gave products having R=C(CH2)Me, instead of the expected vinyl ethers indicating conversion of the ester units by Cp2TiMe2 to methyl ketones followed by methylenation. A reaction of Cp2TiMe2 with the diester (ɳ5-RC5H4)Co(ɳ4-C4Ph3R)(RC(O)OMe) also gave similar results. The study has also been successfully extended to metal sandwich derived amides, thio and seleno esters. By controlling the amount of Cp2TiMe2, the reactions were also stopped at the methyl ketone stage and the methyl ketones were isolated in good yields and characterized. The method provides an easy and direct access to convert organometallic sandwich derived esters and related compounds to 1-methylvinyl derived products.

Reactions of metal sandwich derived esters with Cp2TiMe2 yields 1-methylvinyl derivatives instead of vinyl ethers. The reaction proceeds via formation of methyl ketone derivatives, which can be obtained exclusively by controlling the amount of Cp2TiMe2.Figure optionsDownload as PowerPoint slide