Conformationally rigid chiral ferrocene derivative: Synthesis, resolution and stereochemical assignment

α-Hydroxylactams as Efficient Entries to Diversely Functionalized Ferrociphenols: Synthesis and Antiproliferative Activity Studies

“… a yields in compounds 2B – D taken from the literature [ 19 , 20 , 21 ]; b not applicable; c not done; d value from Ref. [ 25 ]; e compound reported in [ 26 ] by a different route. …”

“…Electrophilic N -acyliminium ions can also be trapped intramolecularly by π-nucleophiles following S E Ar reaction to generate polycyclic products [ 18 ]. In the ferrocene series, Achari et al reported the cyclisation of α−hydroxylactam 6f to the air-sensitive tetracyclic γ-lactam 14 in 79% yield after 2 days in the presence of BF 3 .Et 2 O [ 26 ]. In our case, heating of a mixture of α−hydroxylactam 6f and TsOH to 70 °C in dichloroethane (DCE) also afforded lactam 14 with an 84% yield after only 10 min ( Scheme 2 ).…”

“…From 6f , yield of 84%; from 10f , yield of 83%. This compound has been reported in the literature using another pathway, but NMR signals were not attributed [ 26 ]. 1 H NMR (CDCl 3 ): δ 2.48 (dd, J = 15.4, 5.3 Hz, 1H, CH 2 ), 3.24–2.89 (m, 2H, CH 2 ), 3.45 (s, 5H, Cp), 4.08 (t, J = 2.4 Hz, 1H, C 5 H 3 ), 4.20 (s broad, 1H, C 5 H 3 ), 4.22 (s broad, 1H, C 5 H 3 ), 4.62 (dd, J = 12.4, 6.0 Hz, 1H, CH 2 ), 5.25 (s, 1H, CH-N), 7.50–7.61 (m, 1H, isoindole), 7.62–7.72 (m, 2H, isoindole), 7.99 (d, J = 7.5 Hz, 1H, isoindole).…”

“…This compound has been reported in the literature using another pathway but NMR signals were not attributed [ 26 ].…”

“…Ferrocenyl alcohols 5A – D were prepared according to reference [ 23 ]. The synthesis of compounds 3d , 4d , 18 , and 19 was previously reported in reference [ 25 ] and the synthesis of compounds 3f , 6f and 14 in reference [ 26 ]. Other reagents were obtained from commercial suppliers and used as received.…”