Two substrates, three products: Reactions between ferrocene-carboxaldehyde and dioxaphospholene, characterization and crystal structures of oxygenated C3- and C4-chain-containing ferrocenes

Abstract

Reactions of aldehydes RCHO with 2,2,2-trimethoxy-4,5-dimethyl-1,3,2dioxaphospholene are known to form trimethylbiacetyl-aldehyde-phosphite adducts which upon methanolysis gave rise to the corresponding symmetrical 3-R-2,4-pentanediones (R = aryl, alkyl). Reactions between ferrocenecarboxaldehyde and the biacetyl-trimethylphosphite adduct, whatever the experimental conditions used, afforded three new oxygenated C 3 and C 4 side-chain containing ferrocenyl complexes, namely, 1-ferrocenyl-1,2-propanedione (1, Fc-C(O)C(O)CH 3); Fc = ( 5-C 5 H 5)Fe( 5-C 5 H 4)), 4-methoxy-4-ferrocenyl-3-hydroxy-3-methyl-2butanone (2, Fc-CH(OCH 3)C(CH 3)(OH)C(O)CH 3) as a single diastereoisomer, and the ferrocenyl enone 4-ferrocenyl-3-methyl-3-buten-2-one (3, Fc-CH=C(CH 3)C(O)CH 3) with the enone portion adopting the s-trans confrormation in the solid state. The compounds readily purified by silica gel packed column chromatography were isolated in 31-44% yields, and their constitution is in agreement with elemental analyses, IR and multinuclear NMR spectroscopy, and electrospray mass spectrometry. Their molecular identity and geometry have been confirmed by single-crystal X-ray diffraction.

Reaction between ferrocene-carboxaldehyde and dioxaphospholene: Characterization and crystal structures of an unexpected bisferrocenyldioxolane

“…Very recently, we have shown that in the reaction between ferrocenecarboxaldehyde with a slight excess (15%) of 2,2,2-trimethoxy-4,5-dimethyl-1,3,2-dioxaphospholene, under Ramirez's conditions or slightly modified conditions, ferrocenecarboxaldehyde behaves very differently from aromatic aldehydes [11]. The expected symmetrical target compound 3ferrocenyl-2,4-pentanedione is, indeed, never obtained.…”