B. Venkataiah

Chemical and biochemical modifications of parthenin

Abstract Parthenin, a medicinally important natural sesquiterpenoid and a potent allelochemical underwent different regio- and stereoselective modifications to several interesting analogues by chemical and biochemical means. The compound was treated with various common reducing agents including NaBH4, NaBH 4 I 2 , Na EtOH , Mg MeOH and Zn HOAc as well as with different oxidizing agents including m-CPBA and dilute HCl under different reaction conditions. The retention of the α-methylene-γ-lactone moiety which plays a vital role for bioactivity of the compound was observed in some of the reaction products. The microwave irradiation of the compound afforded anhydroparthenin as the only product. Bakers yeast reduction of parthenin was investigated for the first time and yielded the naturally occurring dihydrocoronopilin.

A minor coumarino-lignoid from Jatropha gossypifolia ☆

1. Subject and source Jatropha gossypifolia Linn. (Euporbiaceae) is a small shrub which grows widely in India. The plant has been used ethnomedically for the treatment of cancerous growths (Hartwell, 1969). The whole plant was collected from the campus in September 1997. A voucher specimen of the plant material (IICP-2048) is preserved in the herbarium of the Indian Institute of Chemical Technology. Several novel diterpenes (jatrophone and its analogues (Kupchan et al., 1970; Taylor et al., 1983) and jatropholones A and B (Purushothaman et al., 1979)) as well as lignans (jatrophan and gadain (Banerji et al., 1984) and venkatasin (Das et al., 1999)) have previously been reported.

Charminarone, a seco-pseudoguaianolide from Parthenium hysterophorus

A novel sesquiterpenoid, charminarone, the first seco-pseudoguaianolide, has been isolated along with several known compounds from the whole plant of Parthenium hysterophorus. The structure of the new compound has been settled as 1,10-seco-dihydroisoparthenin 1,10-dione from its spectral data as well as from its conversion by reductive coupling reaction with Zn/TiCl(4) reagent to the known compound, anhydrodihydroisoparthenin. The reagent Zn/TiCl(4) has been used here for the first time to construct the seven membered ring of a pseudoguaianolide sesquiterpenoid.

Venkatasin, A New Coumarino-Lignoid From Jatropha Gossypifolla1

Abstract A new coumarino-lignoid, venkatasin, has been isolated from the whole plant of Jatropha gossypifolia. the structure of the compound was established from spectral and chemical evidence and finally from its synthesis by regioselective acetylation of a known coumarino-lignoid, cleomiscosin A.

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.

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.

Condensation of phenols with alkylcinnamates in the presence of FeCl31

Ferric chloride catalyses the condensation of phenols with alkylcinnamates to produce 3,4-dihydro-4-arylcoumarins.

CONVERSION OF PARTHENIN TO ANHYDROPARTHENIN USING MICROWAVE IRRADIATION

Abstract The microwave irradiation of parthenin was found to be an useful and convenient method for the preparation of anhydroparthenin, an important intermediate for the synthesis of the analogues of the parent compound.