N. Viswanathan

Triterpenes of calophyllum inophyllum linn

Friedelin (Ia) and three new triterpenes of the friedelin group have been isolated from the leaves of Calophyllum inophyllum. The three new compounds, canophyllal (Ib), canophyllol (Ic) and canophyllic acid (IVa) have been inter-related and their structures established by a direct correlation with oleanenic lactone (XI).

Chemical constituents of Cleistanthus collinus (Roxb.)

Ellagic acid, diphyllin (IIIa) and two new lignan lactones, cleistanthin and collinusin, have been isolated from Cleistanthus collinus (Roxb.). Cleistanthin and collinusin have been shown to have structures IIIc and VI respectively.

Chemical constituents of glochidion hohenackeri

From the bark and roots of Glochidion hohenackeri (Euphordiaceae), in addition to the known 3-epi-lupeol, two new triterpenes glochidone and glochidiol have been isolated and assigned structures I and VIIIa respectively. The stereochemistry of the hydroxyl groups in glochidiol has been determined by the partial synthesis of three of the four possible stereoisomers of the dihydrodiol diacetate (Vd, VId and VIId) which all differ from dihydroglochidiol diacetate (VIIId).

Minor alkaloids of Tylophora asthmatica : Revised structure of tylophorinidine☆

Abstract The structure of the phenolic alkaloid tylophorinidine, isolated from Tylophora asthmatica , has been shown to be 2 . Two other minor alkaloids isolated from the plant have been shown to be d -septicine ( 11 ) and d -isotylocrebrine ( 14 ).

Alkaloids of Tiliacora racemosa Colebr.

Abstract The isolation of tiliacorine, tiliacorinine, nortiliacorinine A and nortiliacorinine B is described, Tiliacorine and tiliacorinine are shown to be diastereoisomers having the structure XIa or XIb.

Alkaloids of Atalantia monophylla correa

Atalaphylline and N-methylatalaphylline, two new acridone alkaloids isolated from Atalantia monophylla, have been shown to have structures (IVa) and (IVb) respectively.

Structure of litsomentol, a new tetracyclic triterpene☆

Litsomentol, a new tetracyclic triterpene, isolated from Litsea tomentosa. Heyne, has been shown to have strocture Ia by degradation and correlation with agnosterol.

Chemical constituents of alstonia venenata R.Br.

Venenatine and isovenenatine, two new indole alkaloids from Alstonia venenata R.Br., have been shown to have structures I and V respectively.

Structure of apetalic acid

Structure Ia assigned earlier to apetalic acid has been confirmed by the synthesis of the degradation product VIb.

Synthesis of 5- and 8-methoxy-yobyrines

5- and 8-Methoxy-yobyrines have been synthesized. The methoxy-yobyrine obtained by dehydrogenation of venenatic acid has been shown to be 5-methoxyyobyrine.