Ferrocene Compounds Containing Heteroelements

Planar chiral ferrocene salen-type ligands featuring additional central and axial chirality

“…The latter derivative is a precursor to 2-hydroxy-1-formyl-ferrocene -a planar chiral analog of salicylaldehyde -and of special interest in view of the anticipated applications of such compounds as planar chiral nitrogen and oxygen-based ligands in stereoselective catalysis. However, hydroxyferrocenes [9][10][11][12] in general are only accessible in protected form by use of hazardous reagents and quite difficult to handle due to their facile oxidation by air, therefore this building block is of limited use for practical applications.…”

“…The organic layer was dried over magnesium sulfate, filtered, and reduced to dryness, yielding 2b as a brown oil (566 mg, 1.71 mmol, 97%). The purity of this material is sufficient for the next step as evidenced by its NMR spectra: 1 [3]); 71.9 (C [7], C [4]); 69.4 (C [6], C [5]); 51.3 (C [9], C [10]); 11.0 (C [1]) ppm (see Fig. 10).…”

“…The crude product was chromatographed on a short alumina column using n-hexane/diethyl ether as eluent, affording 3b as a yellow oil (0.588 mg, 1.58 mmol) in 46% yield. 1 (C [9]); 72.4 (C [3]); 72.4 (C [4]); 68.9 (C [2]); 68.6 (C [7]); 66.2 (C [5]); 65.6 (C [6]); 26.7 (C [10]); 11.0 (C [1]) ppm (see A Schlenk tube was charged with dry tetrahydrofuran (20 mL) and 3b (588 mg, 1.58 mmol). The mixture was cooled to À40°C and sodium hydride (57 mg, 2.37 mmol) was added in one portion under protection from the atmosphere.…”

“…Yield: 9, yellow oil, (1.623 g, 4.7 mmol, 52% [9]),75.0 (C [12]), 67.0 (C [3]), 68.9 (C [1]), 67.4 (C [6]), 66.4 (C [4]), 66.1 (C [5]), 59.4 (C [13]), 58.8 (C [8]), 27.0 (C [10]) ppm (see Fig. 16).…”

“…1 H NMR (CD 2 Cl 2 ): 9.68 (1H, s, H [7]); 7.46 (2H, d, H[18, 13]) ; 7.35-7.25 (3H, m, H[20, 19, 17]); 7.16 (3H, m, H[11, 12, 14]); 7.10 (2H, m, H[16, 15]); 6.61 (1H, s, H[8 0 ]); 4.77 (1H, t, H[5]); 4.59 (1H, t, H[4]); 4.34 (5H, s, H [1]); 4.08 (1H, t, H [6]) ppm. 13 C NMR (CD 2 Cl 2 ): 196.9 (C[7]), 149.4 (C [9]), 145.8 (C [10]), 127.9 (C [13,18]), 127.7 (C [12,17]), 127.5 (C [14,19]), 127.4 (C [11,20] [14]) ppm. 13 …”