Mao-Ping Song

Studies on the cyclometallation of ferrocenylimines

Abstract This review describes the cyclometallation reaction, including cyclomercuration, cyclopalladation and cycloplatination of Schiff base type of ferrocenylimines as well as the transmetallation reaction of cyclometallated ferrocenylimines and the stereochemistry associated with these reactions. The applications of cyclopalladated ferrocenylimines in several fields are also demonstrated in this review. The molecular and crystal structures of the products as well as the absolute configurations of optically active products were established by X-ray diffraction, NMR techniques, IR, UV–vis, etc. The general features of these reactions, especially the regioselectivity and the reaction mechanisms, are discussed. In addition, the structure–property relationships are discussed throughout this investigation. The transmetallation of optically pure cyclometallated ferrocenylimines with other metals such as mercury, tin and tellurium was found to proceed with complete retention of stereochemistry. This discovery led to a convenient method for the synthesis of optically pure cyclometallated organic compounds that are difficult to prepare by using conventional methods. Accordingly, a number of cyclometallated ferrocenylimines have been prepared in optically pure forms, which display surprisingly high angles of rotation.

Visible-light-mediated radical oxydifluoromethylation of olefinic amides for the synthesis of CF2H-containing heterocycles

The visible-light-mediated oxydifluoromethylation of olefinic amides with difluoromethyl sulfones has been explored. This method allows for an efficient and practical synthesis of a variety of CF2H-containing benzoxazines and oxazolines bearing various functional groups under mild conditions.

Synthesis, structure and catalytic properties of CNN pincer palladium(II) and ruthenium(II) complexes with N-substituted-2-aminomethyl-6-phenylpyridines

N-substituted-2-aminomethyl-6-phenylpyridines 2a-c have been easily prepared from commercially available 6-bromo-2-picolinaldehyde in two steps. Reaction of 2a-c with PdCl(2) in toluene in the presence of triethylamine gave the CNN pincer Pd(II) complexes 3a-c in 18-28% yields. The CNN pincer Ru(II) complex 5 containing a Ru-NHR functionality could be obtained in a 71% yield by treatment of 2c with a Ru(II) precursor instead of PdCl(2). Additionally, the related CNN pincer Ru(II) complex 7 containing a Ru-NH(2) functionality has been synthesized by the reaction of 2-aminomethyl-6-phenylpyridine with the same Ru(II) precursor in a 68% yield. All the new compounds were characterized by elemental analysis (MS for ligands), (1)H, (13)C NMR, (31)P{(1)H} NMR (for Ru complexes) and IR spectra. Molecular structures of Pd complex 3c as well as Ru complexes 5 and 7 have been determined by X-ray single-crystal diffraction. The obtained Pd complexes 3a-c were effective catalysts for the allylation of aldehydes as well as for three-component allylation of aldehydes, arylamines and allyltributyltin and their activity was found to be much higher than a related NCN Pd(II) pincer in the allylation of aldehyde. On the other hand, the two new CNN pincer Ru(II) complexes 5 and 7 displayed excellent catalytic activity in the transfer hydrogenation of ketones in refluxing 2-propanol with the latter being much more active. The final TOF values were up to 4510 h(-1) with 0.01 mol% of 5 and 220,800 h(-1) with 0.005 mol% of 7, respectively.

Polymer (fiber)-supported palladium catalyst containing imidazolinyl rings and its application to the Heck reaction

A polymer (fiber)-supported palladium catalyst was synthesized simply from commercially available polyacrylonitrile(PAN) fiber. Its high activity and selectivity for Heck reactions were measured; its activity remained unchanged after being recycled 20 times.

Systematic Study of the Luminescent Europium-Based Nonanuclear Clusters with Modified 2-Hydroxybenzophenone Ligands

The reaction of 2-hydroxybenzophenone derivatives with europium ions has afforded a new family of luminescent nonanuclear Eu(III) clusters. Crystal structure analysis of the clusters reveals that the metal core comprises two vertex-sharing square pyramidal units. Most of these complexes show emissions typical of Eu(3+) ion under visible light excitation (400-420 nm) at room temperature. Photophysical characterization and DFT study reveal a correlation between luminescent efficiencies of Eu(III) complexes and the electronic features of the ligands, which can be tuned by the nature of substituents in the 4-position of the ligands. The ligands with a fluorine substituent possess more suitable triplet energy levels, resulting in more intensive luminescence.

Synthesis, isolation and structural characterization of optically active planar chiral cyclomercurated ferrocenylimines

Abstract Asymmetric cyclomercuration of chiral ferrocenylimines (+)-( R )- 2 and (−)-( S )- 2 with mercuric acetate and subsequent treatment by lithium chloride gave two different pairs of diastereomeric cyclomercurated ferrocenylimines. The four enantiomerically pure compounds with both planar and central chirality were isolated from the two pairs by thin layer chromatography. The structures and absolute configurations of these complexes were determined by single-crystal X-ray analysis and characterized by IR, 1 H NMR, specific rotation and elemental analysis.

Studies on the synthesis and structural characterization of cyclomercurated ferrocenylimines containing heterocyclic ring

Abstract The cyclomercurated ferrocenylimines containing heterocyclic ring can be prepared by the cyclomercuration of acylferrocene, followed by the condensation of the resulting product with the appropriate heterocyclic amine. This procedure provides an efficient method for the synthesis of cyclomerucurated ferrocenylimines containing heterocyclic ring which is difficultly synthesized by the traditional method, i.e. imination and then cyclomercuration. A series of these compounds were synthesized by this new method and characterized. The X-ray crystal structure of [HgCl(η 5 -C 5 H 3 C(CH 3 )ue605N-2-C 5 H 3 N-6-CH 3 ) Fe(η 5 -C 5 H 5 )] ( 3d ) has been determined and the reaction mechanism was proposed.

Ring‐Expanded C‐Nucleoside Analogues of Tiazofurin

Abstract Novel 1,3‐dioxane C‐nucleoside analogues of tiazofurin 2‐[2‐(hydroxymethyl)‐1,3‐dioxan‐5‐methyl‐5‐yl] 1,3‐thiazole‐4‐carboxamide, 2‐[2‐(hydroxymethyl)‐1,3‐dioxan‐5‐ethyl‐5‐yl] 1,3‐thiazole‐4‐carboxamide and 2‐[5‐(hydroxymethyl)‐1,3‐dioxan‐5‐methyl‐2‐yl] furan, 2‐[5‐(hydroxymethyl)‐1,3‐dioxan‐5‐methyl‐2‐yl] thiophen have been synthesized from DMPA and DMBA. Their conformational characteristics have been investigated.

Room Temperature Suzuki Reactions in Aqueous Media under Air by Palladium(II) Complexes with Pyrazole Derived Ligands

Two new palladium complexes with pyrazole derived ligands 2a–2b have been easily prepared and well characterized by elemental analysis, 1H NMR, 13C NMR, and IR spectra. Their detailed structures are determined by a single-crystal X-ray analysis of 2a. The two compounds were successfully applied to the Suzuki coupling reactions of aryl bromides with phenylboronic acid, in aqueous solution at room temperature under air, giving the desired coupled products in good to excellent yields with catalyst loadings as low as 0.01–0.05 mol-%.

Studies on cyclomercuration of bisferrocenylimines

Abstract Cyclomercuration of bisferrocenylimines [(η5-C5H5)Fe{(η5-C5H4)ue5f8CRue605Nue5f8(C6H3-2-R′)}]2, (R=H, CH3; R′=H, CH3, Cl) occurred predominantly in the ortho-position of the substituted ferrocenyl ring to yield double 2-mercurated ferrocenylimines, which arise from activation of two σ(Csp2, ferroceneue5f8H) bonds. The composition and structure of the metallocycles were characterized by elemental analysis, IR, 1H NMR and 2D 13C{1H}-COSY spectra, which confirmed the existence of two five-membered mercuriocycles fused with the ferrocenyl moieties.