V. N. Kamat

Some b-Carboline Alkaloids of Ailanthus malabarica DC

From the bark and roots of Ailanthus malabarica DC. we have isolated and characterised eight β-carboline alkaloids of which four are new. Their structures are elucidated by spectroscopic studies.

The structure of ailanthol, a new triterpenoid from Ailanthus Malabarica DC

Abstract The structure of ailanthot (1), having the triterpene skeleton (20 S )-4 4,8 β - trimethyl-14, 18-cyclo 5a, 13a, 14a, 17a-cholestane, has been assigned by spectral analysis and X-ray crystal structure determination.

Tuberosin, a new pterocarpan from Pueraria tuberosa DC

Tuberosin, a new pterocarpan isolated from Pueraria tuberosa DC. has been identified as 6a,13a-dihydro-10,10-dimethyl-6H,10H-furo[3,2-c:4,5-g′]bis[1]benzopyran-3,6a-diol (III). 7-Methoxy-6-(7-methoxychrornan-3-yl)-2,2-dimethylchroman (X) has been synthesized and shown to be identical with a degradation product from tuberosin.

Benzoquinone derivatives. Part I. Reactions of primary aliphatic amines with embelin (2,5-dihydroxy-3-undecyl-1,4-benzoquinone) and di-o-methylembelin

The reaction of embelin with some primary aliphatic amines has been reinvestigated. Embelin reacts with methylamine to give the 5-methylamino-derivative (2) or the quinone bismethylimine (9), depending on the he conditions. 2-Hydroxy-5-methylamino-3-undecyl-1,4-benzoquinone 1-methylimine (11) is obtained by the reaction of di-O-methylembelin with methylamine. The products of condensation of several primary aliphatic amines with embelin and its di-O-methyl derivative have been characterized.

Clausindine, a novel cyclopropylcoumarin

From the roots of Clausena indica Oliv., a new coumarin, clausindine, has been isolated and shown to have the structure 6-(2,2-dimethylcyclopropyl)furo[3,2-g][1]benzopyran-7-one (I) mainly on spectroscopic evidence. The structure has been confirmed by a synthesis of dihydroclausindine (II). The furanoquinone, furo[3,2-g][1]benzopyran-4,7,9-trione (XII) has also been isolated from the roots of this plant.

Structure of wightionolide: chemical and X-ray analysis

Wightionolide isolated from the leaves of Andrographis wightiana Arn. ex Nees is shown to be 17,19,20-trihydroxy-5β,8αH,9βH,10α-labd-13-en-16,15-olactone (XII). The molecular structure of the dibromo-triacetate (V) of wightionolide has been determined by X-ray diffraction studies.

Revised constitution of Naphtol AS-LB

The 2-hydroxycarbazolecarboxylic acid used in the preparation of Naphtol AS-LB has been shown to be the 1-carboxylic acid and not the 3-carboxylic acid as assumed earlier. Naphtol AS-LB is therefore the p-chloro-anilide of 2-hydroxycarbazole-1-carboxylic acid.

Isolation and structure of wightional and wightiolide from Andrographis wightiana

Abstract Two new ent -labdane-type diterpenoids, wightional and wightiolide have been isolated from the leaves of Andrographis wightiana . Their structures were determined on the basis of extensive 1 H and 13 C, 1 H homonuclear COSY, and HMBC NMR spectroscopic studies. To correlate the newly isolated diterpenes with wightionolide, a number of derivatives of wightionolide have been prepared and characterized.