P. Satyanarayana

Isolation, structure and synthesis of new diarylbutane lignans from Phyllanthus niruri : Synthesis of 5′ -desmethoxy niranthin and an antitumour extractive☆

Abstract The structures of three new lignans (1–3) and a phenolic lignan (4) isolated from Phyllanthus niruri have been determined. The structures (1–3) were confirmed by their total synthesis and that of (4) was by its conversion to (3). The synthesis of (±) 5′ -desmethoxy niranthin (5) and an antitumour extractive (6) is described.

Crystalline constituents of euphorbiaceae-VI: The synthesis and absolute configuration of phyllanthin

Abstract (+)Phyllanthin is now shown to be (8S, 8′S) 3,4,3′,4′,9,9′-hexamethoxy-8-8′-butyrolignan (III) by its synthesis from (a) (−)eudesmin (I) and (b) (+)2,3-diveratryl succinic acid (IV). (+)3,4-diveratryl tetrahydrofuran (VI) from (+)phyllanthin is now shown to posses 3S,4S configuration by its formation from (+)2,3-diveratryl-1,4-butane diol (II).

Crystalline constituents of euphorbiaceae—XI : Revised structure of hypophyllanthin from Phyllanthus niruri linn

A revised structure for hypophyllanthin based on a study of its 220 MHz NMR spectrum and chemical reactions is presented.

Reactions of paulownin, gmelinol and gummadiol with 2,5-dichloro-5,6-dicyanobenzoquinone.

Abstract Paulownin and gmelinol react with DDQ to give 4-pyrone derivatives. Gummadiol reacts under the same conditions to give a pyrone aldehyde and an unsaturated γ-lactone.

Reactions of aryltetralin lignans with DDQ - an example of DDQ oxidation of an allylic ether group.

Abstract The reactions of lintetralin, phyltetralin, nirtetralin and hypophyllanthin with DDQ yield in each case two products which have been identified as an arylnaphthalene aldehyde and its dihydro derivative.

The case for a revised structure for hypophyllanthin - an analysis of the 13C N.M.R. spectra of aryltetralins

A revised structure for hypophyllanthin is proposed on the basis of its 13C n.m.r. spectrum. 13C n.m.r. spectra also support the previously proposed structure for nirtetralin and assist in the structural elucidation of a new aryltetralin lignan.

Oxidative aryl-aryl, aryl-benzyl coupling of lignans-reactions of phyllanthin and haloderivatives with ttfa, ddq, li/thf)))): synthesis of dibenzocyclooctadiene system and phyltetralin

Abstract Treatment of phyllanthin(1) with TTFA in TFA gives dibenzocylooctadiene (2) and phyltetralin (3). Treatment of (1) with DDQ in TFA also affords (2) while with DDQ in acetic acid gives 1-phenylnaphthalenic lignan (4). Synthesis of halophyllanthins (5,6,7) and its Ullmann reaction in ultrasonic conditions offords reductive dehalogneted product (1) instead of (2). Treatment of (1) with POCl3 in TCA gives (+) 3,4-diveratryltetrahydrofuran (8) and its conversion to(9) also reported. Treatment of (8) with TTFA/TFA gives (9).