U.R. Nayak

Chemistry of Ayurvedic crude drugs—I : Guggulu (resin from Commiphora mukul)—1: Steroidal constituents

Structures of two new diterpenoids, cembrene-A and mukulol are reported. Cembrene-A is one of the two most elementary tetraenes derivable from geranyl-geranyl pyrophosphate by C1 → C14 cyclization. Mukulol is also a cembrane derivative and is biogenetically closely related to cembrene-A.

Meroterpenoids—I : Psoralea corylifolia Linn.—1. Bakuchiol, a novel monoterpene phenol

Isolation and structure elucidation of a novel monoterpene phenol, bakuchiol, from the seeds of Psoralea corylifolia Linn, is described.

Chromatography of organic compounds : II. Inverted dry-column chromatography

A column chromatographic method is described, which directly adopts the results of thin-layer chromatography. The method appears to have several advantages over preparative layer chromatography and conventional column chromatography.

Chemistry of ayurvedic crude drugs—III: Guggulu (resin from Commiphora mukul)-3 long-chain aliphatic tetrols, a new class of naturally occurring lipids☆☆☆

Abstract Isolation and structure elucidation of two long-chain aliphatic tetrols, now formulated as octadecan-1,2,3,4-tetrol and eicosan-1,2,3,4-tetrol, from gum-resin of Commiphora mukul, is described. There is evidence for the occurrence of nonadecan-1,2,3,4-tetrol, as well, in the resin. This is the first reported occurrence of such compounds in nature, though the closely related phytosphingosines (e.g. 2-amino-octadecan-1,3,4-triol) are well known.

Studies in sesquiterpenes-XL: Isolongifolene (Part 1): Structure

Isolongifolene, C15H24 an artefact from an acid-catalysed rearrangement of longifolene, is shown to be II.

Meroterpenoids—II : Psoralea corylifolia Linn.—2. Absolute configuration of (+)-bakuchiol

Bakuchiol, a terpene phenol from Psoralea corylifolia Linn has only one asymmetric centre. By suitable correlation with (+)-linalool on the one hand and, with (+)-3-methyl-3-methoxy-carbonyl-n-valeria acid on the other, it has been shown to possess (S)-chirality.

Studies in sesquiterpenes—XXXV: Longicyclene, the first tetracyclic sesquiterpene☆☆☆

A new sesquiterpene hydrocarbon has been isolated from the essential oil of Pinus longifolia, Roxb. and is shown to be the first tetracarbocyclic sesquiterpene; structure II has been assigned to it.

Studies in sesquiterpenes—XLIV : Isolongifolene (part 5): Rearrangement of isolongifolene epoxide

Abstract Isolongifolene epoxide undergoes novel rearrangements on treatment with 1% HCl in CHCl3 or on being exposed to active adsorbent (Al2O3, SiO2-gel). The latter reaction leads to tetracarbocylic derivatives. These reactions fully substantiate the stereochemistry assigned earlier to isolongifolene epoxide.

Studies in sesquiterpenes—XXVIII : BF3-induced rearrangement of eudesmane- and 7-epieudesmane-based 1,2-epoxides☆☆☆

Abstract Rearrangement of 4,5-epoxyeudesmane and 4,5-epoxy-7-epi-eudesmane with BF3-etherate is reported.

Studies in sesquiterpenes-XLV: Structure of an alcohol from hydration of longifolene

Hydration of longifolene under acid catalysis gives, besides longiborneol, one secondary alcohol and a tertiary alcohol. The structure of the secondary alcohol, which is the major alcohol, has now been elucidated. This alcohol, now characterized as longibornan-9-ol, arises by transannular hydration of longifolene.