Sukh Dev

Titanium tetrachloride, an efficient and convenient reagent for thioacetalization1,1

Aldehydes and ketones, when exposed to alkyl thiols or suitable alkane dithiols in presence of titanium tetrachloride, furnish near quantitative yields of the corresponding thioacetals.

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.

Studies in sesquiterpenes—XXXVII: Sesquiterpenoids from the essential oil of zingiber zerumbet smith

A complete analysis of the essential oil from the rhizomes of Zingiber zerumbet Smith, is given and the isolation of several new humulene-based sesquiterpenoids is described.

Biogenetic concepts in terpene structure elucidation

In the development of Natural Products Chemistry,biogenetic considerations have played an important and useful role. In this article, the author cites examples from his work in the area of Terpene Chemistry to highlight the usefulness of these concepts. To illustrate their application in structure elucidation, an example each from sesquiterpene, diterpene, triterpene and sesterterpene chemistry has been described. Role of these concepts in the search for new structural types, congeners and precursors has been brought out. The usefulness of Absolute Stereochemistry Biogenetic Rule has been pointed out.

Organic reactions in a solid matrix-V: Silica-gel supported chromic acid reagents

Pyridinium chromate-on-silica gel, and chromic acid-on-silica gel are described and evaluated as convenient off-the-shelf reagents for efficient oxidation of a variety of secondary and primary alcohols. Pyridinium chromate-on-silica gel can be safely used for the oxidation of alcohols containing acid-labile functions.

Semihydrogenation of acetylenes : Modified lindlar catalyst

Abstract The effect of doping Lindlar catalyst with different metal salts (shown in Table 1) on selectivity, during semihydrogenation of some acetylenes to the corresponding olefins, has been studied. Lindlar catalyst modified with MnCl 2 has been found to be more selective and reproducible.

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.

Studies in sesquiterpenes—XVI : Zerumbone, a monocyclic sesquiterpene ketone☆☆☆

The structure, previously assigned to zerumbone, has been found to be untenable. The ketone has been shown to be monocyclic containing three ethylenic linkages, and has been further correlated with humulene. Results from ozonolysis, and base-catalysed cleavage allowed the compound to be formulated as 2,6,9,9-tetramethyl-2,6,10-cyclo-undecatrien-1-one.

Studies in sesquiterpenes—XXXVIII: Structure of humulene epoxide-I and humulene epoxide-II☆☆☆

Abstract Evidence leading to the assignment of absolute stereostructures I and II to (−)-humulene epoxide-I and (−)-humulene epoxide-II respectively is presented. Partial synthesis of (±)-humulene epoxide-I and -II by epoxidation of humulene, adsorbed on SiO2 gel-AgNO3, with one mole of per acid is described.

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.