T. Prabhakar Rao

Mandapamate, a diterpenoid from the soft coral sinularia dissecta

Mandapamate (3) is a diterpene with an unusual carbon skeleton from the soft coral Sinularia dissecta. The structure of mandapamate(3) was elucidated by interpretation of spectral data, particularly extensive NMR experiments, and was supported by a mechanistic hypothesis for its formation and molecular modelling.

A domino Knoevenagel hetero-Diels-Alder reaction for the synthesis of polycyclic chromene derivatives and evaluation of their cytotoxicity.

A novel octahydrochromeno[4,3-a]xanthen-1(2H)-one derivatives has been prepared using 10mol% dl-proline in ethanol via a domino Knoevenagel hetero-Diels-Alder reaction of alkene-tethered chromene-3-carboxaldehyde with cyclic 1,3-diketones. This is not only the first example on the preparation of highly diastereoselective pentacyclic chromene derivatives from alkene appended chromene-3-carboxaldehyde in one-pot process at ambient temperature but also preliminary evaluation of the cytotoxic activity of these chromene derivatives. Some of these compounds are found to exhibit potent cytotoxicity against two carcinoma cell lines A549 and B-16.

Scandium triflate catalyzed formation of 2,4-dimethoxy-2-methylbenzopyrans

Scandium trifluoromethanesulfonate is found to catalyze an unusual cyclocondensation of o-hydroxybenzaldehydes with 2,2-dimethoxypropane at room temperature to afford a class of new compounds, 2,4-dimethoxy-2-methylbenzopyrans, in high yields.

A facile synthesis of indeno[1,2-b]chromanes catalyzed by scandium triflate

Scandium triflate efficiently catalyzes the cyclocondensation of o-hydroxybenzaldehydes with alkenes such as indene, styrene and allyltrimethylsilane in the presence of trimethyl orthoformate at ambient temperature to afford a new class of compounds, 2,4-disubstitued chromanes in high yields with high diastereoselectivity.

An unusual novel triterpenoid ether, multiflor-7-en-12,13-ether and a new multiflor-7-en-12α-ol from Wattakakavolubilis

Abstract A new multiflor-7-en-12α-ol ( 1 ) and a novel multiflor-7-en-12,13-ether ( 2 ) triterpenoid were isolated from the leaves of Wattakaka volubilis and their structures were established by means of spectroscopic analysis.

A short and highly convergent approach for the synthesis of rutaecarpine derivatives

A novel and highly convergent approach has been developed for the synthesis of quinazolinocarboline alkaloid, rutaecarpine, analogues by the condensation of anthranilamide with chloroaldehyde derived from tryptophol. This method also provides direct access to benzimidazocarbolines and quinazolinoisoquinolines. It is a shorter and metal-free approach which does not require any catalyst or additive to facilitate the reaction.