Jogendra N. Baruah

Stereochemistry of strictic acid and related furano-diterpenes from conyza japonica and grangea maderaspatana

Abstract Extraction of Conyza japonica gave strictic acid, ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid and 5,7-dihydroxy-3,8,4′-trimethoxyflavone. Extraction of Grangea maderaspatana gave (-)-hardwickiic acid, ent-15,16-epoxy-1,3,13(16),14-clerodatetraen-18-oic acid and 3-hydroxy-8-acetoxypentadeca-1,9,14-trien-4,6-diyne. The structure of ent-2β-hydroxy-15,16-epoxy-3,13(16),14-cleroclatrien-18-oic acid was deduced by spectroscopic methods and by partial synthesis from (-)-hardwickiic acid and the stereochemistries of strictic acid and (ent-15,16-epoxy-1,3,13(16),14-clerodatraen-18-oic acid were established by correlation with ent-2β-hydroxy-15,16-epoxy-3,13(16),14-clerodatrien-18-oic acid.

Flavonoids from Millettia pulchra

Abstract Chemical examination of Millettia pulchra yielded (−)-maackiain, (−)-pterocarpin, (−)-sophoranone and the new compounds (6 S , 6a S , 11a R )-6α-methoxypterocarpin, (6 S , 6a S ,11aR)-6α-methoxyhomopterocarpin, (2 S )5,7,4′-trihydroxy-8,3′,5′-triprenylflavanone, (2 R ,3 R )7,4′-dihydroxy-8,3′,5′-triprenyldihydroflavanol, 5,7,2′,4′-tetrahydroxy-6,3′-diprenylisoflavone and 5,7,4′-trihydroxy-2′-methoxy-6,3′-diprenylisoflavone.

A monoacyl galactosylglycerol from sonchus arvensis

Abstract The major lipids isolated in a phytochemical study of Sonchus arvensis were 1,2-dilinolenyl-3- O -β- d -galactopyranosyl- sn -glycerol, 1,2-dilinolenyl-3- O -(α- d -galactopyranosyl-(1→ 6)- O -β- d -galactopyranosyl- sn -glycerol and the previously undescribed 1-linolenyl-3- O -β- d -galactopyranosyl- sn -glycerol.

Guaianolides from Tricholepis glaberrima

Abstract Cynaropicrin and 11,13-dihydrodesacylcynaropicrin were isolated from Tricholepis glaberrima .

Germacranolides from Inula cappa

Abstract Authentic Inula cappa DC afforded a known and four unknown germacranolides related to the ineupatorolides as well as a new 2,3-dihydroxy-9-angeloxygermacra-4-en-6,12-olide. A collection previously described as Inula cappa which yielded only flavones was identified as Blumea balsamifera DC.

Rotenoids from roots of Millettia pachycarpa

Abstract Roots of Millettia pachycarpa furnished retenone, cis -12a-hydroxyrotenone, rot-2′-enonic acid and cis -12a-hydroxyrot-2′-enonic acid.

Guaianolides from Saussurea affinis

Abstract Cynaropicrin, 11β H -11,13-dihydrodesacylcynaropicrin, aguerins A and B, isoamberboin and the new guaianolides saussureolide and 11β H -11,13-dihydrodesacylcynaropicrin 8-β- d -glucoside were isolated from Saussurea affinis .

A new method for cleaving methyl and methylthiomethyl ethers

Abstract Chlorotrimethylsilane (CTMS) and acetic anhydride has been shown to cleave methyl and methylthiomethyl ethers to furnish the corresponding acetates in excellent yield. Tertiary alcohols can be acetylated efficiently with this reagent combination.

Clerodanes from solidago virgaurea

Abstract The isolation and structure determination of four known and eight new cis-clerodane lactones from the aerial parts of Solidago virgaurea are described.

A new method for deprotection of methylthiomethyl ethers

Abstract Methylthiomethyl ethers of primary, secondary and tertiary alcohols are efficiently cleaved by trityl tetrafluoroborate whereas that of phenols remain uneffected under the reaction conditions.