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Chaubey B.,Phosphorus Laboratory | Mobin S.M.,Indian Institute of Technology Bombay | Mobin S.M.,Indian Institute of Technology Indore | Balakrishna M.S.,Phosphorus Laboratory
Dalton Transactions | Year: 2014

The equimolar reaction between 2(2′-hydroxy)phenyloxazoline (1) and PPhCl2 in the presence of triethylamine afforded an unexpected cyclic product, phenyl-benzo-oxazaphosphininone (2), instead of a simple phosphinite derivative A. A similar reaction between 1 and PPhCl2 in 2:1 ratio also yielded the same product 2, but with one equivalent of 2(2′-hydroxy) phenyloxazoline (1) left unreacted. The formation of the cyclic product 2 is due to the P-Cl bond induced oxazoline ring opening followed by the formation of a six-membered γ-lactam type product, 3-(2-chloroethyl)-2-phenyl-2H-benzo[e] [1,3,2]oxazaphosphinin-4(3H)-one (2 also referred to as L). The reactions of 2 with H2O2, elemental sulphur or elemental selenium yielded the corresponding chalcogenides, LE (3, E = O; 4, E = S; 5, E = Se) in quantitative yield. Treatment of 2 with [Ru(η6-Cymene)Cl 2]2, [Pd(COD)Cl2] and [Pd(η3- C3H5)Cl]2 resulted in the formation of [RuCl2(η6-cymene)(L)] (6), [PdCl2{L} 2] (7), and [Pd(η3-C3H5)Cl(L)] (8), respectively. The compound 2 obtained in the 2:1 reaction when treated with [Pd(η3-C3H5)Cl]2 gave the same palladium complex 8 (referred to as 9a), but co-crystallized with bis(oxazolyl)palladacycle (9b) as confirmed by single crystal X-ray analysis. © 2014 The Royal Society of Chemistry. Source


Balakrishna M.S.,Phosphorus Laboratory | Suresh D.,Phosphorus Laboratory | Rai A.,Indian Institute of Technology Bombay | Mague J.T.,Tulane University | Panda D.,Indian Institute of Technology Bombay
Inorganic Chemistry | Year: 2010

Several mixed-ligand copper(I) complexes of cyclodiphosphazanes, [ tBuNP(NC 4H 8X)] 2 (1, X = O; 2, X = NMe), were synthesized by reacting the octanuclear copper(I) complexes [Cu 8(μ 2-I) 8{[ tBuNP(NC 4H 8X)] 2} 4] (3, X = O; 4, X = NMe) with various pyridyl ligands. Interaction of the metallomacrocyclic complex 3 or 4 with pyridine, 2,2′-bipyridine, and 1,10-phenanthroline afforded the neutral dinuclear complexes [(C 5H 5N) 4Cu 2I 2{[ tBuNP(NC 4H 8X)] 2}] (5, X = O; 6, X = NMe), [(2,2′-bpy) 2Cu 2I 2{[ tBuNP(NC 4H 8X)] 2}] (7, X = O; 8, X = NMe), and [(1,10-phen) 2Cu 2I 2{[ tBuNP(NC 4H 8X)] 2}] (9, X = O; 10, X = NMe), respectively, in good yield. The new dinuclear complexes 3, 5, and 7-9 were tested for their cytotoxic properties against human cervical cancer (HeLa) cells. The results indicated that all of the copper complexes have in vitro antitumor activity either similar to or better than that of cisplatin, a widely used anticancer drug. Among the compounds tested, complex 9 showed the most potent inhibitory activity in HeLa cells. In addition, complex 9 was found to potently inhibit proliferation of human breast cancer cells (MCF-7), highly metastatic breast cancer cells (MDA-MB 231), and nontransformed Chinese hamster ovary (CHO) cells. Complex 9 inhibited proliferation of these cells in culture more potently than cisplatin; for example, complex 9 was found to inhibit proliferation of HeLa and MCF-7 cells 3 and 5 times more efficiently than cisplatin. Complex 9 treatment damaged the DNA integrity, blocked the cells in the G1 phase of the cell cycle, and induced apoptosis via a p53-dependent pathway. The molecular structures of complexes 9 and 10 were confirmed by single-crystal X-ray diffraction studies. © 2010 American Chemical Society. Source

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