Biomedical subjects

Krishna P Kaliappan

Publications and source records attributed to Krishna P Kaliappan.

5 recordsLinked to original sources

PubMed2005

Synthesis of [6,n] cis-fused ring compounds via Cr-mediated dearomatisation-ring-closing metathesis.

cis-Fused [6,8], [6,7], [6,6] and [6,5] ring systems containing a cyclohexadiene ring unit, a cycloenone ring and a quaternary carbon at the ring junction were obtained in only two steps from [Cr(CO)3(eta6-p-methoxyphenyl oxazoline)]. The sequence proceeds via diastereoselective addition of three C-substituents across an arene double bond, followed by allylation and ring closing metathesis (RCM). RAMP-hydrazone and (R)-isopropyloxazoline were used as chiral auxiliaries to provide, after removal of the auxiliaries, the enantiomerically highly enriched [6,7] cis-fused system.

Journal Article↗

PubMed2005

A facile domino metathetic route to a thapsigargin skeleton.

A facile synthesis of a 5,7,5-fused ring system that is present in thapsigargins belonging to a novel family of sesquiterpene lactones, guainanolides, using domino enyne-RCM is reported here.

Molecular Conformation↗

PubMed2005

Design and synthesis of novel sugar-oxasteroid-quinone hybrids.

A new class of sugar-oxasteroid-quinone hybrid molecules has been designed and synthesized involving an efficient enyne metathesis/Diels-Alder reaction strategy.

Carbohydrates↗

PubMed2004

A cascade enyne/ring closing metathesis approach to angularly fused dioxatriquinanes.

An expedient and first tandem enyne/ring closing metathesis approach on a sugar furanose template leading to a novel angularly fused dioxa-triquinane is described here.

Alkynes↗

PubMed2003

Combinatorial discovery of two-photon photoremovable protecting groups.

A design principle for a two-photon photochemically removable protecting group based on sequential one-photon processes has been established. The expected performance of such groups in spatially directed photoactivation/photodeprotection has been shown by a kinetic analysis. One particular molecular class fitting into this design, the nitrobenzyl ethers of o-hydroxycinnamates, has been presented. An initial demonstration of two-photon deprotection of one such group prompted further optimization with respect to photochemical deprotection rate. This was accomplished by the preparation and screening of a 135-member indexed combinatorial library. Optimum performance for lambda >350 nm deprotection in organic solvent was found with 4,5-dialkoxy and -cyano substitution in the nitrobenzyl group and 4-methoxy substitution in the cinnamate.

Cinnamates↗