Ram Prakash Sharma

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.

Absolute stereochemistry of the cadinenes from eupatorium trapezoideum

Abstract Chemical examination of Eupatorium trapezoideum has furnished five cadinenes 1 a, 2 a, 2 b, 4 a & 5 and a degraded cadinene 3 a whose stereostructures are presented in this paper. The absolute stereochemistry of the major component 1 a has been determined by application of Horeaus method as well as chemical correlation studies and has been confirmed by X-ray analysis of 1 f thus suggesting that it belongs to the amorphane group.

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.

Tin(II) chloride dihydrate reduction of β,γ -unsaturated nitro-alkenes

Abstract β,γ -Unsaturated nitro-alkenes have been converted into α,β -unsaturated ketones in good yield by tin(II) chloride dihydrate in tetrahedrofuran.