Mani Upreti

Diterpene glycosides from Stevia rebaudiana

Three novel diterpene glycosides were isolated for the first time from the commercial extract of the leaves of Stevia rebaudiana, along with several known steviol glycosides, namely stevioside, rebaudiosides A-F, rubusoside and dulcoside A. The new compounds were identified as 13-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy] ent-kaur-15-en-19-oic acid (1), 13-[(2-O-β-d-glucopyranosyl-3-O-β-d-glucopyranosyl-β-d-glucopyranosyl)oxy]-16β-hydroxy-ent-kauran-19-oic acid (2) and 13-methyl-16-oxo-17-nor-ent-kauran-19-oic acid-β-d-glucopyranosyl ester (3) on the basis of extensive 2D NMR and MS spectroscopic data as well as chemical studies.

Synthetic Study on the Relationship Between Structure and Sweet Taste Properties of Steviol Glycosides

The structure activity relationship between the C16-C17 methylene double bond on the aglycone of steviol glycosides and the corresponding impact on their sweet taste has been reported here for the first time. It has been observed that converting stevioside and rebaudioside A to their corresponding ketones by switching the doubly bonded methylene on C-17 for a ketone group actually removes the sweet taste properties of these molecules completely. Regenerating the original molecules tends to restore the sweet taste of both the steviol glycosides. Thus this C16-C17 methylene double bond in rebaudioside A and stevioside can be regarded as a pharmacophore essential for the sweetness property of these molecules.

Synthesis and antimicrobial evaluation of some new fluorinated spiro[[1,5] -benzothiazepin-2,3′[3′H]-indol]-2′(1′H)-ones

Abstract A series of fluorinated spiro[1,5-benzothiazepin-2,3′[3′ H ]-indol]-2′(1′ H )-ones have been prepared by the reaction of 2-aminobenzene-thiols with 1,3-dihydro-3-[2-phenyl/(4-fluorophenyl)-2-oxoethylidene)-indol-2(1 H )-ones ( I ) under microwave irradiation in open vessels using ethylene glycol as energy transfer medium and thermally in absolute ethanol saturated with hydrogen chloride gas. The comparative studies indicated that the microwave assisted organic synthesis has advantages of significantly reduced reaction time, improved yields and cleaner reactions as compared to the conventional method. All synthesized compounds have been characterized by analytical and spectral data and were screened for their antifungal activity against Alternaria alternata and Fusarium oxysporium and antitubercular activity against Mycobacterium tuberculosis IVb (R = F, X = F) and IVe (R = F, X = CH 3 ) have shown above 90% inhibition in reducing fungal growth of A. alternata while IVa (R = H, X — F) has shown 98% antitubercular activity on primary screening.

SYNTHESIS OF 8-SUBSTITUTED-2-CARBOXY-4-(4-FLUOROPHENYL)-2,3-DIHYDRO-1,5-BENZOTHIAZEPINES

Abstract The reactions of 5-substituted-2-aminobenzenethiols with δ-(4-chlorobenzoyl)- and δ3-(4-bromobenzoyl)acrylic acids have been carried out in methanol containing traces of glacial acetic acid to yield in a single step, 8-substituted-2-carboxy-4-(4-chlorophenyl and 4-bromophenyl)-2,3-dihydro-1,5-benzothiazepines, the substituents being CI, Br as halogen; CH3 as alkyl, and OCH3 and OC2H5 as alkoxyl. The structural assignments have been made by a study of microanalyses of the elements and IR, 1H NMR and mass spectral studies of the title compounds.

Synthesis of ent-kaurane diterpene monoglycosides.

Synthesis of two ent-kaurane diterpene glycosides, steviol 19-O-β-D-glucopyranosiduronic acid (steviol glucuronide, 5 ), and 13-hydroxy ent-kaur-16-en-19-oic acid-β-D-glucopyranosyl ester (7) has been achieved from a common starting material, steviol, using phase transfer catalyst. Also, synthesis of an additional 17-nor-ent-kaurane glycoside, namely 13-methyl-16-oxo-17-nor-ent-kauran-19-oic acid-β-D-glucopyranosyl ester (10) was performed using the starting material isosteviol and similar synthetic methodology. Synthesis of all three steviol glycosides was performed using straightforward chemistry and their structures were characterized on the basis of 1D and 2D NMR as well as mass spectral (MS) data.

Syntheses of 1,5-Benzothiazepines. Part 20. Syntheses of 8-Substituted-2,5-dihydro-2-(4-N-dimethylaminophenyl)-4-(4-methoxyphenyl)-1,5-benzothiazepines

Seema Pant, Babita Singhal, Mani Upreti and Umesh C. Pant*Department of Chemistry, University of Rajasthan, Jaipur-302004 IndiaTel. 0091 141 651969Received: 13 January / Accepted: 6 March 1998 / Published: 15 May 1998Abstract : 8-Substituted-2,5-dihydro-2-(4-N-dimethylaminophenyl)-4-(4-methoxyphenyl)-1,5-benzothiaze-pines (5a-e) have been synthesized by reacting 5-substituted-2-aminobenzene-thiols (1a-e) with 4-N-dimethylaminobenzal-4-methoxy acetophenone ( 2) in dry ethanol saturated with hydrogen chloride gas. Theproducts were tested for purity by tlc and characterized by elemental analysis for carbon, hydrogen andnitrogen and IR,

SYNTHESES OF 1,5-BENZOTHIAZEPINES, PART XVI: SYNTHESES OF 8-ETHOXY/FLUORO-2-CABOXY-4-(FLUORINATED ARYL) -2,3-DIHYDRO-1,5-BENZOTHIAZEPINESAS PROSPECTIVE CARDIOVASCULAR AGENTS

Abstract Syntheses of fluorinated 8-ethoxy/fluoro-2-carboxy-4-substituted ary-2,3-dihydro1,5-benzothiazepines having substitutents as chloro, methyl and trifluoromethyl have been achieved by the reaction of 5-ethoxy/-fluoro-2-aminobenzenethiols with fluorinated 3-substituted benzoyl-2-propenoic acids in toluene with catalytic amount of trifluoroacetic acid. The progress of the reactions was monitored by t.1.c. studies. Structures of the title compounds are established by IR, PMR and mass spectral studies and microestimation data of nitrogen.

SYNTHESIS OF DIHYDRO-2-(2-PHENYL-INDOLE-3-YL)-4-ARYL-1,5-BENZOTHIAZEPINES

Abstract A series of novel dihydro-2-(2-phenyl-indole-3-yl)-4-aryl-1,5-benzothiazepines (III) have been synthesized by the reaction of 2-aminothiophenol with 2-phenyl-3-(3-aryl-3-oxo-propen-1-yl)-indoles (I) in ethanol and gl. acetic acid mixture. Chalcones (I) were prepared by the reaction of 2-phenyl-1H-indole-3-carboxaldehyde with substituted acetophenones in ethanolic sodium hydroxide. The compounds have been characterized on the basis of elemental and spectral studies and were screened for their antifungal and antibacterial activities.

ONE-POT SYNTHESIS OF A NOVEL TETRACYCLIC RING SYSTEM: BENZOPYRANO-1,2,4-TRAZOL0[3,4-B][1,3,4] THIADIAZEPINES AND THEIR ANTIFUNGAL ACTIVITY

Abstract A series of novel 11-alkyl-2-chloro-6a, 7-dihydro-6H-7(4-aryl)-6-phenyl[1]benzopyrano-1,2,4-triazolo[3,4-b]benzothiadiazepines(IV) have been synthesized by the reaction of 4-amino-5-alkyl-3-mercapto-1,2,4-triazoles (I) with (E)-6-chloro-3-(4-chloro/methoxy-benzyLidene)flavanones (IIa/b) in refluxing toluene, containing piperidine as catalyst. The compounds have been characterized on the basis of elemental and spectral studies and have been screened in vitro for antifungal activity against Rhizoctonia solani, Fusarium oxysporum and Colletotrichum capsici. All the compounds have shown excellent activity against these pathogens.

Microwave-induced One-pot Synthesis and Biological Screening of 8-Substituted 2,5-Dihydro-1,5-benzothiazepin-2-spiro-3′-3′H-indol-2′-(1′H)-ones

The concept of microwave-induced enhancement of organic reactions has been utilized in a one-pot synthesis of spiro[benzothiazepin-indol]ones.