Karangula Jyothi

Heterogeneous catalytic asymmetric aminohydroxylation of olefins using LDH-supported OsO4

Recently prepared layered double hydroxides (LDH)-supported OsO 4 , developed by the ion-exchange technique, was employed for catalytic asymmetric aminohydroxylation (AA) of olefins of varied nucleophilicity using Chloramine-T and (DHQ) 2 PHAL to afford chiral vicinal N-protected amino alcohols, important building blocks for many biologically active compounds and precursors for chiral ligands with moderate yields and ees for the first time. Strong electron deficient olefins undergo AA reaction offering better yields than the less electron deficient and electron rich olefins due to the greater polarization of Os=NTs group in the former. The catalyst could be reused without any loss of enantioselectivity albeit a reduced activity.

Silica Gel-Supported Cinchona Alkaloid-OsO4 Complex for Catalytic Heterogeneous Asymmetric Dihydroxylation of Olefins by H2O2 using a Titanium Silicalite-Based Coupled Catalytic System

A triple catalytic system designed for asymmetric dihydroxylation of olefins, composed of NMM and two divergent heterogeneous catalysts, titanium silicalite and silica gel-supported 1,4-bis(9-O-dihydroquinidinyl)phthalazine [SGS-(DHQD) 2 PHAL)]-OsO 4 complex relays the transport of two electrons from olefin to H 2 O 2 used as a terminal oxidant to provide chiral diols with good yields and high enantiomeric excesses in a single pot.

MCM-41 anchored cinchona alkaloid for catalytic asymmetric dihydroxylation of olefins: a clean protocol for chiral diols using molecular oxygen

MCM-41 anchored 1,4-bis(9-O-quininyl)phthalazine (MCM-(QN)2PHAL)-OsO4, is prepared for the first time and used in the heterogeneous asymmetric dihydroxylation of olefins to afford diols with good to excellent enantiomeric excesses in the presence of N-methylmorpholine N-oxide, K3Fe(CN)6 or molecular oxygen as cooxidants.

A new bifunctional catalyst for tandem Heck-asymmetric dihydroxylation of olefins.

A new bifunctional catalyst consisting of active palladium and osmium species anchored on silica gel through a mercaptopropyl spacer and a cinchona alkaloid respectively has been prepared for the first time and used in the heterogeneous tandem Heck-asymmetric dihydroxylation of olefins to afford diols with excellent yields and enantiomeric excesses (ees) in presence of N-methylmorpholine N-oxide or K3Fe(CN)6 as cooxidants.