Suresh Babu Meruva

A catalyst-free rapid, practical and general synthesis of 2-substituted quinazolin-4(3H)-ones leading to luotonin B and E, bouchardatine and 8-norrutaecarpine

A remarkably rapid but microwave/ultrasound/catalyst-free method has been developed for the construction of a quinazolin-4(3H)-one ring using formamide as an efficient ammonia precursor and PEG-400 as an effective solvent. The methodology afforded various 2-substituted quinazolin-4(3H)-one derivatives in good yield via a three-component reaction of isatoic anhydride, aldehydes and formamide in air. This single methodology was extended successfully to the synthesis of several alkaloids e.g. leutonin B and E, bouchardatine and 8-norrutaecarpine.

An oxidative amidation and heterocyclization approach for the synthesis of β-carbolines and dihydroeudistomin Y

Summary A novel synthetic methodology has been developed for the synthesis of dihydro-β-carboline derivatives employing oxidative amidation–Bischler–Napieralski reaction conditions using tryptamine and 2,2-dibromo-1-phenylethanone as key starting materials. A number of dihydro-β-carboline derivatives have been synthesized in moderate to good yields using this methodology. Attempts were made towards the conversion of these dihydro-β-carbolines to naturally occurring eudistomin alkaloids.

Synthesis of enantiomerically pure N-(2,3-dihydroxypropyl)arylamides via oxidative esterification

Summary A highly efficient synthesis of enantiomerically pure (S) and (R)-isomers of N-(2,3-dihydroxypropyl)arylamides has been developed with good overall yields in a two step process. The key step involves the ring opening of the chiral epoxide with a nitrogen heterocyclic carbene (NHC) and further rearrangement to chiral N-(2,3-dihydroxypropyl)arylamides in high yields and enantioselectivity. During the reaction, no erosion in chiral purity was observed.

Asymmetric synthesis of (–)-leiocarpin A via (–)-(S)-goniothalamin employing Julia–Kocienski olefination

ABSTRACT A concise and enantioselective syntheses of antileukemic natural products such as (–)-(S)-goniothalamin and (–)-leiocarpin A has been accomplished in excellent yields. By employing reported conditions on suitable substrates via Julia–Kocienski olefination, intramolecular lactonization, and subsequently dehydroxylative olefination, (–)-(S)-goniothalamin was synthesized. Then Sharpless asymmetric dihydroxylation–intramolecular Michael addition on (–)-(S)-goniothalamin provided (–)-leiocarpin A. GRAPHICAL ABSTRACT