Iron(II) complexes containing unsymmetrical P-N-P' pincer ligands for the catalytic asymmetric hydrogenation of ketones and imines.

After their treatment with LiAlH4 and then alcohol, new iron dicarbonyl complexes mer-trans-[Fe(Br)(CO)2(P-CH═N-P')][BF4] (where P-CH═N-P' = R2PCH2CH═NCH2CH2PPh2 and R = Cy or iPr or P-CH═N-P' = (S,S)- Cy2PCH2CH═NCH(Me)CH(Ph)PPh2) are catalysts for the hydrogenation of ketones in THF solvent with added KOtBu at 50 °C and 5 atm H2. Complexes with R = Ph are not active. With the enantiopure complex, alcohols are produced with an enantiomeric excess of up to 85% (S) at TOF up to 2000 h(-1), TON of up to 5000, for a range of ketones. An activated imine is hydrogenated to the amine in 90% ee at a TOF 20 h(-1)and TON 99. This is a significant advance in asymmetric pressure hydrogenation using iron. The complexes are prepared in two steps: (1) a one-pot reaction of phosphonium dimers ([cyclo-(PR2CH2CH(OH)(-))2][Br]2), KOtBu, FeBr2, and Ph2PCH2CH2NH2 (or (S,S)-Ph2PCH(Ph)CH(Me)NH2 for the enantiopure complex) in THF under a CO atmosphere to produce the complexes cis- and trans-[Fe(Br)2(CO)(P-CH═N-P')]; (2) the reaction of these with AgBF4 under CO(g) to afford the dicarbonyl complexes in high yield (50-90%). NMR and DFT studies of the process of precatalyst activation show that the dicarbonyl complexes are converted first to hydride-aluminum hydride complexes where the imine of the P-CH═N-P' ligand is reduced to an amide [P-CH2N-P'](-) with aluminum hydrides still bound to the nitrogen. These hydride species react with alcohol to give monohydride amine iron compounds FeH(OR')(CO)(P-CH2NH-P'), R' = Me, CMe2Et as well as the iron(0) complex Fe(CO)2(P-CH2NH-P') under certain conditions.

[Rapid determination of the multi-marker ingredients in Heterosmilacis Japonicae Rhizoma and Sophorae Flavescentis Radix with near-infrared diffused reflection spectroscopy].

A rapid NIRS method for determination of macrozamin in Heterosmilacis japonicae rhizoma (HJR), and the total content of oxymatrine and matrine (OMT + MT) as well as the total content of oxysophocarpine and sophocarpine (OSC + SC) in sophorae flavescens radix (SFR) was developed to explore the application feasibility of NIRS for the quality assurance system of Chinese patent drugs. The contents of macrozamin in HJR samples, and OMT + MT and OSC + SC in SFR samples were determined by HPLC as reference values. The NIR spectra of the samples were measured in a diffused reflection mode. The different characteristic wavebands and pretreatment methods were optimized. The quantitative calibration models between the NIR spectra and the content reference values of marker components in HJR and SFR samples, were established with partial least square method, and further optimized through the cross validation and external validation. The contents of macrozamin in 88 batches of HJR samples were over the range of 0.36-12.88 mg · g(-1). The total contents of OMT + MT and OSC + SC in 75 batches of SFR samples were over the range of 8.87-66.31 and 2.30-15.11 mg · g(-1), respectively. The performance of the final models for macrozamin, OMT + MT and OSC + SC was evaluated well according to correlation coefficients (r), root mean square error of cross-validation (RMSECV) and root mean square error of prediction (RMSEP). The R2 values of the cross-validation for macrozamin, OMT + MT and OSC + SC were 0.9025, 0.9491 and 0.9137, and those of RMSECV were 0.961, 2.45 and 0.724 mg · g(-1) respectively. The R2 values of external validation for the three models were 0.9817, 0.9826 and 0.9609, and those of RMSEP were 0.693, 2.27 and 0.658 mg · g(-1), respectively. This is the first report on rapid determination of macrozamin in Heterosmilacis japonicae rhizoma, and oxymatrine, matrine, oxysophocarpine and sophocarpine in sophorae flavescens radix by NIRS method. The presented method can fulfill the requirement of rapid acquirement of chemical information of raw medicinal materials prior the manufacturing of compound Kushen injection.