Ring-methyl activation in pentamethylcyclopentadienyl complexes. 8. Introduction of organic functionalities at substituted tetramethylcyclopentadienyl complexes of ruthenium(II)

A series of complexes derived from nucleophilic attack at the CH2Cl of [(eta(5)-C5Me4CH2Cl)Ru(CO)(2)Cl], 1, by a wide variety of organic reagents are described. Most reactions proceed in good yield and do not appear to affect the Ru(CO)(2)Cl group, even though they are performed under quite stringent (oxidizing, acidic, or hydrolytic) conditions. Hydrolysis of 1 in the presence of collidine gives the alcohol complex, [(C5Me4CH2OH)Ru(CO)(2)Cl], 2, which is oxidized (Me2SO, oxalyl chloride) to [(C5Me4CHO)Ru(CO)(2)Cl], 4a, and which can be further oxidized (KMnO4) to [(C5Me4CO2H)Ru(CO)(2)Cl], 10. The alcohol complex 2 forms esters [(C5Me4CH2O2CR)Ru(CO)(2)Cl], 3 (R = Me, CH2=CH, 2-furyl, and 2-thienyl), on reaction with RCOCl/Et3N. The aldehyde 4a is a very versatile starting material: It forms acetals such as [(C5Me4CH(OCH2)(2))Ru(CO)(2)Cl], 5a, with ethylene glycol. It reacts with phenylhydrazine and p-toluidine in the presence of acid to give [(C5Me4CH=NNHPh)Ru(CO)(2)Cl], 6, and [(C5Me4CH=N-p-To)Ru(CO)(2)Cl], 7. It also reacts with carbon nucleophiles such as PhMgBr to give [(C5Me4CH(OH)Ph)Ru(CO)(2)Cl], 8a, with lithium enolates to give [(C5Me4CH(OH)R)Ru(CO)(2)Cl], 8b-d (R = 2-oxocyclohexyl, MeCOCH2, and PhCOCH2), and with Wittig reagents to give [(C5Me4CH=CHR)Ru(CO)(2)Cl], 9 (R = EtCO2, Ph, MeCO, and PhCO). The carboxylic acid 10 forms the acid chloride [(C5Me4COCl)Ru(CO)(2)Cl], which reacts with diisopropylamine to give the amide [(C5Me4CON(i-Pr)(2))Ru(CO)(2)Cl], 12. The structures of complexes [(C5Me4CH(oH)Ph)Ru(CO)(2)Cl], 8a, [(C5Me4CH(OH)CH2COPh)Ru(CO)(2)Cl], 8d, and [(E-C5Me4CH=CHPh)Ru(CO)(2)Cl], 9b, have been confirmed by X-ray determinations.