T. Ravindranathan

Use of solid superacid (sulphated SnO2) as efficient catalyst in tacile transesterification of ketoesters

Facile one to one transesterification of ketoesters catalysed by solid superacid (sulphated SnO2) is described.

INTERCONVERSION OF OXATHIOLANES AND CARBONYLS UNDER ESSENTIALLY IDENTICAL CONDITIONS

Abstract A catalytic, non-aqueous protocol for the interconversion of oxathiolanes and carbonyl compounds at room temperature is described.

Enzymatic kinetic resolution studies of racemic 4-hydroxycyclopent-2-en-1-one using Lipozyme IM®

Abstract Enzymatic kinetic resolution studies of (±)-4-hydroxycyclopent-2-en-1-one 2 were taken up in organic solvents by transesterification with vinyl acetate and alcoholysis of its acetate 3 as an alternative to the desymmetrization of meso-cyclopentenediol to provide faster and economic access to enantiomerically pure 4-(R)-tert-butyldimethylsilyloxycyclopent-2-en-1-one 1. Parameters were screened using Lipozyme IM® as catalyst. Although enantioselectivity observed was moderate (E=24, by alcoholysis of 3 with 2-butanol), trends in the effect of solvent, water content and alcohol structure showed useful directions for screening of other enzymes for optimization of the method to useful levels of efficiency.

Facile deprotection of allyl esters mediated by solid superacid (sulphated SnO2)

Abstract Facile deprotection of allyl esters in the presence of sulphated SnO2 is described.

Polymer supported nitrobenzaldehyde : Efficient, highly selective catalytic, deprotection of oxathioacetals☆

Abstract Oxathioacetals are smoothly deprotected to carbonyl compounds by polymer supported nitrobenzaldehyde at room temperature under CF3SO3Si(Me)3 catalysed conditions.

An efficient synthesis of α-Cuparenone

Abstract Synthesis of α-Cuparenone is described. The key step involved arephotorearrangement of α-halo arylketone (4) to 1-methyl-1-(p-tolyl)acetic acid (5) and extremely mild, essentially neutral, room temperature /3-aza-claisen reaction of N-allylamide (6).

A facile and efficient method for deprotection of thioketones

Abstract A catalytic, high yielding transformation of thioketones to ketones at room temperature is described.

Desymmetrization of meso-cyclopenten-cis-1,4-diol to 4-(R)-hydroxycyclopent-2-en-1-(S)-acetate by irreversible transesterification using Chirazyme®

Abstract The parameter optimization study for the desymmetrization of meso-cyclopenten-1,4-diol 1 through irreversible transesterification using an immobilized lipase from Mucor meihei, i.e., Lipozyme®/Chirazyme® is presented. The enzyme was studied for the transesterification of 1 in various organic solvents by varying reaction parameters such as the nature of acyl donor, temperature, enzyme quantity etc., to afford optically active 4-(R)-hydroxycyclopent-2-en-1-(S)-acetate 2 of >98% enantiomeric excess in >60% yield.

Quinolone antibiotics: Study of reactivity and impurity profile of piperazine with chloro-fluoro-quinolone carboxylic acid in aqueous medium

Abstract The reaction of 7-chloro-1-cyclopropyl-6-fluoro-4-oxo-1,2-dihydroquinoline-3-carboxylic acid with piperazine in water was studied. The product ciprofloxacin was isolated and the impurity formed in the reaction was isolated and characterized as 1-cyclopropyl-7-chloro-6-piperazinyl-4-oxo-1,2-dihydroquinoline-3-carboxylic acid. Similarly norfloxacin was also synthesised.

A simple synthesis of (±)-α-cuparenone

Abstract A short and simple synthesis of (±)-α-cuparenone from 4-methyl-acetophenone via acid catalyzed decomposition of a β,γ-unsaturated-α-diazoketone is described.