Preparation and some chemistry of ferrocenylethynyl ketones

Abstract

Reactions of Fc′(CHO)2 1 (Fc′ = 1,1′-ferrocenediyl) with LiC{triple bond, long}CR gave substituted propargylic alcohols Fc′{CH(OH)C{triple bond, long}CR}2 (R = SiMe3 2, Fc 9). Oxidation (MnO2) of these alcohols afforded the bis(alkynyl ketone)s Fc′{C(O)C{triple bond, long}CR}2 (R = SiMe3 3, Fc 10), the former being accompanied by the partially desilylated Fc′{C(O)C{triple bond, long}CH}-1-{C(O)C{triple bond, long}CSiMe3}-1′ 4. The reaction between 4 and RuCl(dppe)Cp in the presence of Na[BPh4] gave the cyclic vinylidene complex [Ru{{double bond, long}C{double bond, long}C[C(O)Fc′C(O)CH{double bond, long}CH]}(dppe)Cp]BPh4 5. The diastereomers were separated by flash chromatography (2) or preparative t.l.c. (9) to give the cis (2a, 9a) and trans (2b, 9b) isomers. Cyclisation of each isomer to the corresponding ferrocenophane was catalysed by pTSA to give Fc′{[CH(C{triple bond, long}CR)]2O} (R = SiMe3 6a, 6b; Fc 11a, 11b), of which 6a, 6b could be desilylated to Fc′{[CH(C{triple bond, long}CH)]2O} 7a, 7b, and further transformed into the bis(η2-alkyne-dicobalt) complexes Fc′{[CH(η2-C2H[Co2(μ-dppm)(CO)4])]2O} 8a, 8b with Co2(μ-dppm)(CO)6. Molecular structures of 3, 5, 6a, 6b, 7a, 7b and 10 were determined by single-crystal XRD methods. © 2009.