Krishna C. Joshi

Metal chelates of fluorinated 1,3-diketones and related compounds

Der Ubersichtsartikel befast sich mit der Darstellung, der Rontgenstrukturanalyse und den spektroskopischen Eigenschaften von uber 80 Metallchelaten von fluorierten 1,3-Diketonen.

New terpenoid aldehydes from Kigelia pinnata: crystal structure of pinnatal

From the root bark of Kigelia pinnata (Bignoniaceae) two aldehydes, norviburtinal(6-formylcyclo-penta[c]pyran) and pinnatal, 11-formyl-2, 3, 3a, 5, 10, 10a, 11, 11a-octahydro-8-hydroxy-3, 11-dimethyl-3, 10a-epoxy-1H--cyclopent[b]anthracene-5, 10-dione, have been isolated. The structures were determined by spectroscopic methods, and X-ray crystallographic analysis of pinnatal.

Xanthanolides from Xanthium indicum

Abstract From the aerial parts of Xanthium indicum, in addition to known compounds, two new xanthanolides were isolated and the stereochemistry of xanthumin

Diterpenes derived from clerodanes from Pulicaria angustifolia

Abstract The investigation of Pulicaria angustifolia afforded, in addition to known triterpenes and caryophyllene epoxide, four methyl esters of diterpenes, all derived from clerodane. Three of them are derivatives of seco-nidoresedic acid. The structures were elucidated by spectroscopic methods.

Synthesis, 19F NMR spectral studies and antibacterial evaluation of some new fluorine containing indole derivatives

Abstract The condensation behaviour of various fluorine containing 3-indolylimino derivatives with mercaptoacetic acid and with chloroacetyl chloride has been studied. The cyclocondensation of 3-arylimino-2H-indol-2-ones(III; Ar = 4FC6H4, 3CF3C6H4, 2Cl3CF3C6H3, 2,3,4,5-tetra-FC6H and 2,3,4,6-tetra-FC6H) with mercaptoacetic acid yielded 3′-phenylspiro [3H-indole-3,2′-thiazolidine]-2,4′(1H)-diones (IV) in 75–90% yields. Reaction of anil (III; Ar = 2,3,4,5-tetra-FC6H) with chloroacetyl chloride gave spiro[azetidine-2,3′- 3H indole]-2′, 4(1′H)-dione (VI) in 75% yield. However, similar reactions in the case of 3-(pentafluorophenylimino)-2H-indol-2-one did not give the expected spiro compounds: 3-indolylmercaptoacetic acid (V) was obtained with mercaptoacetic acid, while the product from chloroacetyl chloride could not be characterized. Further, the reactions of various fluorine containing isatin-3-hydrazones (VII; Ar = 4C6H4, C6F5, 1,2,4-triazino [5,6-b] indole, benzimidazole) with mercaptoacetic acid also did not give corresponding spiro compounds and unchanged compounds (VII) were recovered. The compounds synthesized have been characterized by their analytical and spectral (IR, 1H NMR & 19F NMR) data, and were screened for antibacterial activity.

Studies in spiroheterocycles. Part XVI. Synthesis of new flourine-containing spiro-3-indoline derivatives

Abstract The reaction of fluorinated phenylthioureas, with some new fluorine-containing 3-(2-oxocycloalkylidene) indol-2-ones (2) in ethanolic KOH medium, yielded a series of new fluorine containing 5′,6′-cyclopenta-2′-thioxo-3′-phenyl spiro [3H-indole-3,4′(3′H)-pyrimidin] -2(1H)-ones and 2′,4′a,5′,6′,7′,8′,- hexahydro-2′-thioxo-3′-phenyl spiro [3H-indole-3,4′(3′H)-quinazolin] -2(1H)-ones in 55–68% yields. New fluorine-containing 3-(2-oxocycloalkylidene) indol-2-ones (2) were synthesized by the knoevenagel reaction of indole-2,3-diones with cyclic ketones (cyclopentanone/cyclohexanone) in presence of diethylamine as a basic catalyst followed by dehydration in concentrated hydrochloric acid and glacial acetic acid medium. All the compounds have been characterized by their analytical and spectral (IR, 1 H NMR, 19 F NMR and Mass) data.

Fluorine-containing bioactive benzimidazoles

Benzimidazole derivatives are important in the field of biochemistry and medicine. Although several reviews exist on benzimidazoles and some of the well-known fluorinated derivatives like astemizole, pimozide, benperidol and droperidol, there is nothing comprehensive on the fluorinated derivatives. In this article, we have tried to cover the synthesis and biological activity (where reported) of all types of fluorinated benzimidazoles. The text has been classified on the basis of the position of fluorine or of fluorinated groups on the benzimidazole system, as follows: I On a nitrogen atom (a) On one nitrogen (b) On both the nitrogens II On imidazolyl carbon III On the benzene ring (a) At one position (b) At more than one position IV On more than one atom (a) On the benzene ring and on the nitrogen atom (b) On the benzene ring and on imidazolyl carbon (c) On the imidazolyl carbon and nitrogen atom (d) On the benzene ring, nitrogen atom and imidazolyl carbon (e) On two benzimidazole rings

Acanthospermolides and other constituents from Blainvillea acmella

Abstract The aerial parts of Blainvillea acmella afforded, in addition to widespread triterpenes, desacetyl ovatifolin, desacyl grazielic acid tiglate, 8β-[2-methylbutyryloxy]-9β-hydroxy-14-oxo-acanthospermolide, four new germacranolides and seven acanthospermolides. The roots gave ovatifolin, two widespread thiophenacetylenes and two daucane derivatives. Comparison of the data with those of cyclochaenin required a revision of its structure. The structures were elucidated by high field 1 H NMR spectroscopy. Biogenetic relationships and taxonomic aspects are discussed briefly.

A diterpene with a new carbon skeleton from Solidago altissima

Abstract An Indian sample of Solidago altissima afforded in addition to several clerodanes already isolated from other Solidago species, a diterpene with a new carbon skeleton. Furthermore a ketone and a new anethole derivative were present.

Synthesis and mass fragmentation pattern of fluorinated spiro [3H-indole-3.9′-[9H] xanthene]-1′,2,8′ (1H,2′H,5′H)-triones

Abstract Some new fluorine containing spiro-xanthenes and spiro-acridines have been synthesized. Spiro-xanthenes were obtained by the reaction of fluorinated indole-2,3-diones with 1,3-cyclohexanedione by three different routes. Further, spiro-xanthenes were treated with ammonium acetate or fluorinated anilines in acidic medium resulting in corresponding spiro-acridines. All synthesized compounds have been characterized on the basis of elemental analyses, IR, 1 H and 19 F NMR and Mass spectral studies.