Novel quinoline and naphthalene derivatives as potent antimycobacterial agents.

We have designed and synthesized both the quinoline and naphthalene based molecules influenced by the unique structural make-up of mefloquine and TMC207, respectively. These compounds were evaluated for their anti-mycobacterial activity against drug sensitive Mycobacterium tuberculosis H37Rv in vitro at single-dose concentration (6.25 microg/mL). The compounds 22, 23, 26 and 27 inhibited the growth of M. tuberculosis H37Rv 99%, 90%, 98% and 91% respectively. Minimum inhibitory concentration of compounds 22, 23, 26 and 27 was found to be 6.25 microg/mL. Our molecular modeling and docking studies of designed compounds showed hydrogen bonding with Glu-61, Tyr-64 and Asn-190 amino acid residues at the putative binding site of ATP synthase, these interactions were coherent as shown by Mefloquine and TMC207, where hydrogen bonding was found with Tyr-64 and Glu-61 respectively. SAR analysis indicates importance of hydroxyl group and nature of substituents on piperazinyl-phenyl ring was critical in dictating the biological activity of newly synthesized compounds.

Benzoyl transfer reactivities of racemic 2,4-di-O-acyl-myo-inosityl 1,3,5-orthoesters in the solid state: molecular packing and intermolecular interactions correlate with the ease of the reaction.

Racemic 2,4-di-O-acyl-myo-inosityl 1,3,5-orthoesters undergo transesterification catalyzed by sodium carbonate with varying ease of reaction in the solid state; reactions in solution and melt do not show such varied differences. An interesting crystal of a 1:1 molecular complex of highly reactive racemic 2,4-di-O-benzoyl-myo-inosityl 1,3,5-orthoformate and its orthoacetate analogue exhibited better reactivity than the latter component alone. Single-crystal X-ray structures of the reactants have been correlated with the observed differences in the acyl-transfer efficiencies in the solid state. Although each of the derivatives helically self-assembles around the crystallographic 2(1) axis linked through O-H...O hydrogen bonding, the pre-organization of the reactive groups (C=O [El] and OH [Nu]), C-H...O and the C-H...pi interactions are significantly more favourable for the reactive derivatives than the less reactive ones. Bond-length distributions also showed differences; the O-C bond of the axial benzoyl group, which gets cleaved during the reaction, is longer (1.345-1.361 A) relative to the chemically equivalent O-C bond of the equatorial benzoyl group (1.316-1.344 A) in the reactive derivatives. These bond-length differences are not significant in the less reactive derivatives. The overall molecular organization is different too; the strikingly discrete helices, which may be viewed as "reaction tunnels" and are held by interhelical interactions, are clearly evident in the reactive derivatives in comparison with the less reactive ones.

Sulfonate protecting groups. Improved synthesis of scyllo-inositol and its orthoformate from myo-inositol.

A convenient high yielding method for the preparation of scyllo-inositol and its orthoformate from myo-inositol, without involving chromatography is described. myo-Inositol 1,3,5-orthoformate was benzoylated to obtain 2-O-benzoyl-myo-inositol 1,3,5-orthoformate. This diol was tosylated and the benzoyl group removed by aminolysis in a one-pot procedure to obtain 4,6-di-O-tosyl-myo-inositol 1,3,5-orthoformate. Swern oxidation of the ditosylate, followed by sodium borohydride reduction and methanolysis of tosylates gave scyllo-inositol 1,3,5-orthoformate (isolated as the triacetate). Aminolysis of the acetates followed by acid hydrolysis of the orthoformate moiety with trifluoroacetic acid gave scyllo-inositol in an overall yield of 64%.