P. Madhusudhan

Two efficient methods for the conversion of camptothecin to mappicine ketone, an antiviral lead compound☆

Abstract Two simple and efficient methods for the conversion of the naturally occurring alkaloid, camptothecin to mappicine ketone, an antiviral lead compound, have been described. The first method involved the treatment of camptothecin with borontrifluoride etherate and the second method utilised the microwave irradiation of the alkaloid.

Regioselective reduction of the α,β-double bond of some naturally occurring dienamides using NaBH4I2 system☆

Abstract The regioselective reduction of the α, β - double bond of the naturally occurring dienamides, piperine, piperlonguminine and N - isobutyl - 2E, 4E - decadienamide was achieved by using NaBH 4 I 2 system.

The first conversion of camptothecin to (S)-mappicine by an efficient chemoenzymatic method

Camptothecin has been converted for the first time to (S)-mappicine via mappicine ketone, which is the sole product of the microwave irradiation of camptothecin. Bakers yeast reduction of mappicine ketone yielded (S)-mappicine in high optical purity.

Enantioselective synthesis of (S)- and (R)-mappicines and their analogues

Abstract The naturally occurring alkaloids, camptothecin and mappicine ketone were converted to racemic mappicine acetate which was enantioselectively hydrolyzed to ( S )- and ( R )-mappicines in high optical purity using bakers yeast and a lipase, Amano PS. Treatment of the racemic acetate with bakers yeast afforded ( S )-mappicine while with Amano PS yielded (R)-mappicine. 9-Methoxycamptothecin and 9-methoxymappicine ketone underwent similar conversion to ( S )- and ( R )-9-methxymappicines.

Transformation of the conjugated dienamide system of some natural alkamides to the β,γ-unsaturated amide function using ZnHOAc

Abstract The naturally occurring dienamides, piperine, piperlonguminine, guineensine, brachystamide-B and pergumidiene were converted to the corresponding β, γ-unsaturated amides by using Zn HOAc .

A convenient and efficient one-pot conversion of ketones into amides under microwave irradiation using silica gel supported NaHSO 4 catalyst

A simple and rapid conversion of ketones into the corresponding amides in high yields has been developed by treatment with hydroxylamine hydrochloride under microwave irradiation in the presence of silica gel supported NaHSO4 catalyst.

BAKER'S YEAST TREATMENT OF SOME NATURALLY OCCURRING AMIDES

Abstract The styryl double bond of brachystamide B and guineensine was found to be reduced by bakers yeast but that of piperine and piperlonguminine was uneffected. N-Isobutyl-2E,4E-decadienamide was also unchanged by bakers yeast treatment.

Fries rearrangement of arylsulfonates and sulfonanilides under microwave irradiation

Fries rearrangements of arylsulfonates and sulfonanilides under microwave irradiation afforded hydroxy and aminoaryl sulfones respectively in very short times and in excellent yields. The conversion showed high selectivity to produce 2- and 4- hydroxyaryl sulfones as the major and minor products respectively from arylsulfonates and 2-aminoaryl sulfones exclusively from aryl sulfonanilides.

Clay Catalysed Convenient Isomerization of Natural Furofuran Lignans Under Microwave Irradiation

Abstract The naturally occuring furofuron lignans, (+)-sesamin, (+)-eudesmin, (+)-syringaresinol and (+)-yangambin underwent rapid isomerization to their corresponding C-7 epimers under microwave irradiation in the presence of montmorillonite KSF as catalyst.

SELECTIVE ACETYLATION OF ALIPHATIC HYDROXYL GROUP IN THE PRESENCE OF PHENOLIC HYDROXYL GROUP USING SILICA GEL SUPPORTED BF3 CATALYST

ABSTRACT Selective acetylation of aliphatic hydroxyl group in the presence of phenolic hydroxyl group was achieved conveniently and efficiently by treatment with EtOAc in the presence of silica gel supported BF3 catalyst.