G. Srimannarayana

13C NMR studies of some complex natural oxygen heterocyclics : Structure of millettin, a novel isoflavone isolated from Millettia Auriculata

Abstract 13C NMR spectra for a variety of isoflavones are presented and analysed. The novel isoflavone, Millettin (Xa) is shown to be closely related to Auriculatin (II). While comparison of the 13C NMR spectra did not readily prove the orientation of the fused pyran ring, the use of acetylation shifts showed unambiguously that the fusion in linear, rather than angular.

Four isoflavones and two 3-aryl coumarins from stems of Derris scandens

Abstract Chemical examination of the chloroform extract of the stems of Derris scandens has yielded a new isoflavone, eturunagarone. In addition to the prev

Phenanthrene and stilbenes from Pterolobium hexapetallum

Abstract From the stems of Pterolobium hexapetallum phenanthrene, tri- O -methyl resveratrol, methyl tri-O-methyl gallate, pterostilbene, resveratrol, methyl gallate were isolated. The natural occurrence of phenanthrene has not previously been reported. The structures were determined by analytical and spectroscopic methods.

Fleminone, a flavanone from the stems of Flemingia macrophylla

Abstract A new flavanone, designated fleminone, was isolated from the petrol extract of the stems of Flemingia macrophylla . Its structure was established as 5,2′-dihydroxy-4′-methoxy-6-(3-methylbut-2-enyl)-6″,6″-dimethyl-pyrano (2″,3″: 7,8) flavanone on the basis of physical and chemical evidence.

A BUTYROLACTONE LIGNAN DISACCHARIDE FROM FLACOURTIA RAMONTCHI

beta-Sitosterol, beta-sitosterol-beta-D-glucopyranoside and a butyrolactone lignan disaccharide, ramontoside, were isolated from the heartwood of Flacourtia ramontchi. The structure of ramontoside was determined as diphyllin-4-O-[beta-D-glucopyranosyl(1---4)]-beta- 2,3-di-O-methyl-D-xylopyranoside by hydrolysis and spectral data.

Isoflavans from Millettia racemosa

Abstract From the stems (without bark) of Millettia racemosa , new isoflavans- 3 R (+)-millinol, 3 R (+)-millinol-B and 3 R (+)-cyclomillinol were isolated. Their structures were determined by analytical and spectroscopic methods. All these compounds showed promising insecticidal activity.

5-Methoxyfurano(2″,3″:7,8)flavone from the stems of Ochna squarrosa

Abstract A new furanoflavone, 5-methoxyfurano(2″,3″:7,8)flavone, is reported from the stems of Ochna squarrosa .

Flemiphyllin, an isoflavone from stems of Flemingia macrophylla

Abstract A new isoflavone, designated flemiphyllin, was isolated from a petrol extract of the stems of Flemingia macrophylla. Its structure was established as 5,7,4′-trihydroxy-3′,5′,8-tri(3-methylbut-2-enyl) isoflavone on the basis of physical and chemical evidence.

Facile Synthesis of 7‐Methoxy‐2‐aryl‐3‐phenyl/or‐H‐8‐[2‐(4,6‐dimethyl‐3,5‐dicarbethoxy‐pyridyl)]‐4H‐1‐benzopyran‐4‐ones

Abstract Condensation of 8‐formyl‐7‐methoxy‐2‐phenyl‐4H‐1‐benzopyran‐4‐ones (5a–f) with ethyl‐3‐aminocrotonate (6) in glacial acetic acid under Hantzsch conditions afforded 7‐methoxy‐2‐aryl‐3‐phenyl/or‐H‐8‐[2‐(4,6‐dimethyl‐3,5‐dicarbethoxy‐pyridyl)]‐4H‐1‐benzopyran‐4‐ones (7a–f) in good yields.

A New and Facile Synthesis of Chroman-3-ols, 3,4-Dihydro-2H-[1]-Benzopyran-3-ols

Abstract o-Allyl phenols react with m-chloroperoxybenzoic acid (m-CPBA) in dry chloroform to give chroman-3-ols in a single step in good yields (93–96%).