Showing papers by "Dillip Kumar Chand published in 2006"
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TL;DR: In this article, selective oxidation of sulfides to sulfoxides and sulfones is achieved by H 2 O 2 using MoO 2 Cl 2 as the catalyst, and various substituted sulfides having functional groups such as methyl, methoxy, bromo, nitro, alkene, alkyne, alcohol, ester, aldehyde and an oxime are successfully and selectively oxidized without affecting the sensitive functionalities.
135 citations
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TL;DR: The pyridine-appended nonchelating bidentate ligands 1 and 2 were complexed with a naked Pd(II) ion for the construction of molecular cage compounds to produce novel structures that are combinations of the M(n)L( n) type frameworks.
Abstract: The pyridine-appended nonchelating bidentate ligands 1,4-bis(3-pyridyl)benzene (1) and 4,4'-bis(3-pyridyl) biphenyl (2) were complexed with a naked Pd(II) ion for the construction of molecular cage compounds. Prior to these experiments, the complexation of the ligands with cis-[Pd(en)(NO3)2] was also examined, because self-assemblies from the cis-protected Pd(II) ion were expected to be simple motifs that constitute the assemblies from naked Pd(II) ion. The structures of the self-assembled compounds resulting from 1 and [Pd(en)(NO3)2] depended on the solvent employed. In aqueous solution, an M2L2 trenchlike compound was obtained. In dimethyl sulfoxide, however, a mixture of the M2L2 trench and an M3L3 macrocycle was found in equilibrium, the dynamic nature of which was confirmed by the concentration-dependent nature of the species. At higher concentration, an M4L4 macrocycle was mostly observed. The complexation of 1 with naked Pd(II) ions was expected to produce novel structures that are combinations of the M(n)L(n) type frameworks. A peculiar tetrahedral M4L8 assembly was obtained quantitatively from 1 and Pd(NO3)2, rather than the smallest possible M3L6 double-walled triangle. Interestingly, the use of Pd(CF3SO3)2 resulted in the sole formation of the latter structure. Thus, the anion is important as a template in the formation of these assemblies. Ligand 2, which contains an extra p-phenylene unit compared to 1, behaved in a similar manner when treated with [Pd(en)(NO3)2], but showed subtle differences with naked Pd(II) ions. With Pd(NO3)2, 2 gave mostly a tetrahedron along with a double-walled triangle. With Pd(CF3SO3)2, this longer ligand formed a double-walled triangle with a negligible amount of tetrahedra. A single discrete assembly of a perfect tetrahedron was obtained from 2 and Pd(II) ions by choosing p-tosylate as a counterion.
109 citations
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TL;DR: The transition metal perchlorates used in this article were found to be more efficient than the already reported metal triflates and s, p-block per-chlorates.
Abstract: Acetylation of alcohols, phenols, amines, thiols and aldehydes is performed using acetic anhydride as acylating agent and M(ClO 4 ) 2 ·6H 2 O as catalyst where M is Mn, Co, Ni, Cu and Zn at room temperature under solvent free conditions. Transition metal perchlorates used here are found to be more efficient than the already reported metal triflates and s, p-block perchlorates. Substrates containing acid sensitive protecting groups are acylated successfully without any cleavage of the protection. Remarkably, less nucleophlic thiols (e.g. 2-mercaptobenzothiazole) are acylated with reasonable yields using transition metal perchlorates as catalyst whereas otherwise active acylation catalyst Mg(ClO 4 ) 2 was found to be inefficient.
35 citations
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TL;DR: In this article, a selective and controlled aerobic oxidation of activated benzyl alcohols to the corresponding aldehydes is achieved in refluxing CH3CN using catalytic amounts of MoO2Cl2(L)2 where L is DMSO, DMF or THF.
Abstract: Selective and controlled aerobic oxidation of activated benzyl alcohols to the corresponding aldehydes is achieved in refluxing CH3CN using catalytic amounts of MoO2Cl2(L)2 where L is DMSO, DMF or THF. The catalysis reactions are possible under open air in the absence of any other external co-oxidants. However, bubbling of oxygen to the reaction mixture is useful in making the catalysis reaction sustained. Both activated and deactivated varieties of α-substituted benzyl alcohols (secondary alcohols) give ketones in the same reaction conditions. The inexpensive catalyst is selective towards activated primary benzyl alcohols and also, being mild, stops the oxidation at the aldehyde stage, making it synthetically useful. Copyright © 2006 John Wiley & Sons, Ltd.
20 citations
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TL;DR: In this paper, the formation of three examples of self-assembly Pt(II) cage molecules of general formula [Pt m (ligand) n ](NO 3 ) 2 m is achieved from Pt (II) and ligands.
13 citations
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TL;DR: In this article, selective oxidation of sulfides to sulfoxides and sulfones is achieved by H 2 O 2 using MoO 2 Cl 2 as the catalyst, and various substituted sulfides having functional groups such as methyl, methoxy, bromo, nitro, alkene, alkyne, alcohol, ester, aldehyde and an oxime are successfully and selectively oxidized without affecting the sensitive functionalities.
Abstract: Selective oxidation of sulfides to sulfoxides and sulfones is achieved by H 2 O 2 using MoO 2 Cl 2 as the catalyst. Various substituted sulfides having functional groups such as methyl, methoxy, bromo, nitro, alkene, alkyne, alcohol, ester, aldehyde and remarkably an oxime are successfully and selectively oxidized without affecting the sensitive functionalities.
8 citations