An Alternative Approach to Chiral 2-[1'-(Diphenylphosphanyl)ferrocenyl]-4,5-dihydrooxazoles

Publisher Website
Google Scholar
Abstract
The reaction of 1'-(diphenylphosphanoyl)ferrocenecarbonyl chloride, generated in situ by the reaction of 1'-(diphenylphosphanoyl)ferrocenecarboxylic acid and oxalyl chloride, with chiral aminoalcohols gave amidoalcohols [Fe(η5-C5H4P(O)Ph2)(η5-C5H4C(O)NHCHRCH2OH)] 13, (R = i-Pr, (S); R = i-Pr, (R); R = t-Bu, (S) and R = Ph, (R). The amidoalcohols 13 were converted to 2-[1'-(diphenylphosphanoyl)ferrocen-1-yl]-4,5-dihydrooxazoles 14 by ring-closing reaction with a tosyl chloride-triethylamine mixture. Subsequent reduction of 14 with trichlorosilane in the presence of triethylamine afforded the corresponding 2-[1'-(diphenylphosphanyl)ferrocenyl]-4,5-dihydrooxazoles 10. Compounds 13d, 14d and 10d were subjected to a detailed 1H, 13C and 31P NMR analyses. CD spectra of all 10 were measured. trans-Dichlorobis{(S)-2-[1'-(diphenylphosphanyl)ferrocenyl]-4-isopropyl-4-5-dihydrooxazole-κP}palladium(II) (15) was synthesised and its solid-state structure was determined by single-crystal X-ray diffraction.