Asish De

Application of directed metalation in synthesis. Part 4: Expedient synthesis of substituted benzo[b]thiophene and naphthothiophene ☆

Abstract A short, simple and inexpensive synthesis of several diversely substituted benzo[ b ]thiophenes and one naphthothiophene is described. The method involves introduction of methylsulfanyl group ortho - to the amide function of readily available N , N -diethylamides of aryl carboxylic acid by directed metalation. Thioindoxyls, obtained in high yields through side-chain deprotonation and cyclisation in one pot, are reduced to benzo[ b ]thiophene or napthothiophene.

Application of directed metallation in synthesis. Part 3: Studies in the synthesis of (±)-semivioxanthin and its analogues

Abstract The synthesis of several analogues of (±)-semivioxanthin including five thiophene analogues, using directed metalation are reported. The strategy consisted of the synthesis of functionalized naphthalene or benzo[ b ]thiophene as building blocks followed by annelation of the pyrone.

Application of directed metallation in synthesis: total synthesis of model compounds related to semivioxanthin

Abstract Two model compounds related to the naturally occurring antifungal compound semivioxanthin were synthesized from readily available starting materials using a directed metallation–transmetallation–allylation–cyclization protocol.

A convenient synthesis of benz-1,2-oxazine derivatives

An expedient synthesis of benz-1,2-oxazine derivatives involving nitrene insertion on a methoxy group is described.

Designing of an artificial light energy converter in the form of short-chain dyad when combined with core-shell gold/silver nanocomposites

UV-vis absorption, steady state and time resolved fluorescence and absorption spectroscopic investigations demonstrate that the short chain dyad MNTMA when combined with gold-silver core-shell (Au@Ag) nanocomposite , forms elongated conformers in the excited state whereas for the dyad - Ag (spherical) system the majority of dyads remains in a folded conformation. In the dyad-core-shell nanocomposite system, energy wasting charge recombination rate slows down primarily due to elongated conformation and thus it may be anticipated that this hybrid nanocomposite system may serve as a better light energy conversion device.