The new series of tellurium-containing trigonal bipyramidal clusters [Te2CrM2(CO)10]2- (M = Cr, 2a; Mo, 2b; W, 2c) has been synthesized from the ring closure reactions of the ring complexes [Te2Cr2M2(CO)18]2- (M = Cr, 1a; Mo, 1b; W, 1c) in refluxing acetone solutions. The mixed-metal ring complexes [Te2Cr2M2(CO)18]2- (M = Mo, 1b; M = W, 1c) can be obtained readily from the metal expansion reactions of the dichromium complex [Te{Cr(CO)5}2]2- with M(CO)6 (M = Mo, W) in MeCN. The ring complexes [Te2Cr2M2(CO)18]2- (M = Mo, 1b; W, 1c) each display a Te2M2 ring with each Te atom externally coordinated with one Cr(CO)5 group, while the new group 6-containing trigonal bipyramidal clusters [Te2CrM2(CO)10]2- (M = Cr, 2a; Mo, 2b; W, 2c) each consist of a CrM2 trigonal plane capped above and below by two tellurides. Complexes 1b−2c are fully characterized by IR, 125Te NMR spectroscopy, and single-crystal X-ray analysis. This paper describes a new methodology to the highly strained group 6 metal clusters [Te2CrM2(CO)10]2- (M = Cr, 2a; Mo, 2b; W, 2c) from the ring closure reactions of their corresponding ring complexes [Te2Cr2M2(CO)18]2- (M = Cr, 1a; Mo, 1b; W, 1c), and the interesting transformations and structural features of the new complexes 1b−2c are systematically studied as well.

Pharmaceutically interesting, angular bis-benzimidazoles with three appendages have been synthesized successfully through a diversity-oriented approach with soluble support under microwave irradiation. Polymer immobilized o-phenylenediamine was selectively N-acylated with 2-chloro-3-nitrobenzoic acid in a primary aromatic amino moiety. The obtained amide was cyclized to benzimidazole in an acidic condition, and subsequently nucleophilic aromatic substitution with different amines was performed. Successive reduction, cyclization with various aldehydes and activated isothiocyanates yielded angular biheterocyclic benzimidazoles in good quantities. Reaction progress on polymer support was precisely monitored using the conventional proton NMR spectroscopy. Preliminary screening results showed some of these interesting compounds exhibited moderately to good inhibition against vascular endothelial growth factor receptor 3 (VEGFR-3), which is related to invasion and migration of cancer cells.

The first isolation of the monotelluride-bridged chromium carbonyl complexes [Et 4 N] 2 [Te-{Cr(CO)has been achieved from the reaction of Te powder with 3 equiv of Cr(CO) 6 in the presence of [Et 4 N]Br in concentrated KOH/EtOH solution. According to X-ray analysis, anion 1 displays a pyramidal geometry with the Te atom bonded to three Cr(CO) 5 fragments and anion 2 exhibits a nonlinear structure with the Te atom coordinated with two Cr(CO) 5 moieties. Complex 1 can transform to 2 in the presence of Cr(CO) 6 /KOH/EtOH solution. Conversely, 2 can convert back to 1 upon the reaction with Cr(CO) 6 in MeCN. Interestingly, the novel C-O activation of MeOH is observed when 1 was treated with NaOH/MeOH solution at 70 °C, giving the Te-methylated product [Et 4 N][MeTe{Cr(CO) 5 } 2 ] ([Et 4 N][3]). Complex 2 is reactive toward some organic solvents. It can react with CH 2 Cl 2 to form the CH 2 -bridged tetrachromium complex [Et 4 N] 2 [CH 2 {TeCr 2 -(CO) 10 } 2 ] ([Et 4 N] 2 [4]) and can transform to the known tetrachromium tritelluride complex [Et 4 N] 2 [Te 3 {Cr(CO) 5 } 4 ], in MeOH solution. Besides, we also found that 2 can undergo oxidative coupling with [Cu(MeCN) 4 ]BF 4 in MeOH to form the dimeric open cluster [Te 2 {Cr(CO) 5 } 4 ] 2and can react with NaOH in MeOH to give the dimeric ring complex [Te 2 Cr 4 (CO) 18 ] 2-.Complexes 1-4 are fully characterized by spectroscopic methods and singlecrystal X-ray analysis. This paper describes that complexes 1 and 2 are important intermediates for a series of tellurium-containing polychromium complexes, and the interesting structural features of the resultant new polychromium carbonyl complexes are compared as well.

The Pictet-Spengler reaction, using polyethylene glycol immobilized tryptophan ester with a variety of ketones, was achieved by refluxing condition in acidic chloroform. The linear as well as cyclic ketones were employed. All the ketones were reacted within 6-8 h to furnish soluble polymer-supported tetrahydro-β-carboline in good yields. Further expansion at N-terminus of tetrahydro-β-carbolines was achieved through a reaction with chloroacetyl chloride. Finally, the 2,5-diketopiperazine skeleton was constructed over a β-carboline by amination of the resulting N-chloroacetamides and subsequent intramolecular cyclization leading to cleavage of the polymer; constitutes a traceless synthesis of tetracyclic molecular architecture. Significantly, this strategy affords a straightforward and efficient approach for the construction of biological promising molecules with high purity and good yields.