Synthetic studies towards the phloroglucin natural product hyperforin: construction of the fully prenylated bicyclic core

An approach towards the highly functionalized bicyclo[3.3.1]nonan-9-one core of the complex PPAP-based natural product hyperforin, with the full complement of prenyl substituents in required stereo-disposition, is delineated.

Investigations towards the synthesis of a CD-steroid intermediate

The development of a new synthesis of 2,6,7,7a-tetrahydro-lβ-hydroxy-4-formyl-7a-methylindene was undertaken involving the preparation of 2,6,7,7a-tetra-hydro-1β-hydroxy-4-methoxymethyl-7a-methylindene because of the erratic yield in the last oxidation step of the reported synthesis of the former compound. Although various attempts to prepare the latter were not successful, interesting rearrangement products, the dienone, 5,6,7,7a-tetrahydro-4,7a-dimethyl-5H-indene-1,5-dione and the tricyclic keto alcohol, 2,6-diketo-3-methyltricyclo(5,2,1,0)decan-8-ol, were obtained, the structures of which have been proved by spectral data. Mechanisms for the formation of these products have been proposed.

Synthetic application of the diels-alder adduct of β-trans-ocimene and maleic anhydride-II. An approach towards the synthesis of valerenic acid

By a series of reactions the Diels-Alder adduct IV of maleic anhydride and β-trans-Ocimene gave 1-hydroxy-1,4-dimethyl-7-hydroxymethyloctahydroindane (XII). Its further synthetic elaboration furnished 1,4-dimethyl-7-(2-ethoxycarbonyl-1-propenyl)-Δ1-octahydroindane of the valerenic acid skeleton.

Studies directed towards the synthesis of schisanartane and related complex nortriterpenoids: construction of models of the peripheral ABC and FGH segments of rubrifloradilactone C

A conceptually unifying and flexible approach to the ABC and FGH segments of the nortriterpenoid rubrifloradilactone C, each embodying a furo[3,2-b]furanone moiety, from the appropriate Morita-Baylis-Hillman adducts is delineated. (C) 2010 Elsevier Ltd. All rights reserved.

A bifunctional approach towards the mild oxidation of organic halides: 2-dimethylamino-N,N-dimethylaniline N-oxide

The titled reagent incorporates an oxygen-centred nucleophile and a basic moiety�in a suitably mutual orientation�in the same molecule. It oxidises various primary benzylic bromides to the corresponding aromatic aldehydes under relatively mild conditions (MeCN/rt�50°C/6�24 h) in high yields (83�97%), and is thus a useful alternative to the Kornblum procedure.

An Eventful Synthetic Approach Towards the Biologically Potent Natural Product Ottelione A: Enantio-, Regio- and Stereoselective Construction of the Bicyclic Core

A novel synthetic approach towards the recently reported anti-tumor and anti-tuberculor natural product ottelione A from the readily available Diels-Alder adduct of cyclopentadiene and p-benzoquinone is delineated. Our short strategy, besides being enantio-, regio- and stereoselective, charts an eventful course and is inherently well-suited for adaptation towards diverse synthetic analogues of this biologically potent natural product.

Bridgehead substitution of 1-methoxybicyclo[2.2.2]oct 5-en-2-one derivatives: towards the synthesis of (±)-allo-cedrol [khusiol]1

Preparation of the key intermediates, 11 and 21, required for the synthesis of (+/-)-allo-cedrol (khusiol) is reported by a novel methodology involving the substitution at the bridgehead position of 1-methoxybicyclo[2.2.2]oct-5-en-2-one derivatives

Towards the total synthesis of tashironin related allo-cedrane natural products: further exploitation of the oxidative dearomatization-IMDA-RCM triad based strategy

Synthetic studies directed towards allo-cedrane based, tashironin sibling natural products, involving some deft functional group manipulations on a preformed tetracyclic scaffold, are delineated. (C) 2011 Elsevier Ltd. All rights reserved.

Model studies directed towards the synthesis of functionalised chiral A-ring derivatives of taxanes

Model studies, starting from the monoterpene R-carvone, directed towards the synthesis of chiral A-ring derivatives of taxanes with oxygen functionalities at C-2, 9 and 13 carbon atoms as in taxol is described.

Synthetic studies directed towards the potent cytotoxic natural product ottelione A: stereoselective construction of the complete framework

A stereoselective strategy for the rapid acquisition of the complete framework (dideoxyottelione A) of the promising cytotoxic agent ottelione A, with four contiguous stereogenic centres on a hydrindane skeleton and a sensitive 4-methylenecyclohex-2-enone functionality, from the readily available Diels-Alder adduct of 1,2,3,4-tetrachloro-5,5-dimethoxycyclopentadiene and norbornadiene, is delineated.

Towards the concept of hydrodynamic cavitation control

A careful study of the existing literature available in the field of cavitation reveals the potential of ultrasonics as a tool for controlling and, if possible, eliminating certain types of hydrodynamic cavitation through the manipulation of nuclei size present in a flow. A glass venturi is taken to be an ideal device to study the cavitation phenomenon at its throat and its potential control. A piezoelectric transducer, driven at the crystal resonant frequency, is used to generate an acoustic pressure field and is termed an �ultrasonic nuclei manipulator (UNM)�. Electrolysis bubbles serve as artificial nuclei to produce travelling bubble cavitation at the venturi throat in the absence of a UNM but this cavitation is completely eliminated when a UNM is operative. This is made possible because the nuclei, which pass through the acoustic field first, cavitate, collapse violently and perhaps fragment and go into dissolution before reaching the venturi throat. Thus, the potential nuclei for travelling bubble cavitation at the venturi throat seem to be systematically destroyed through acoustic cavitation near the UNM. From the solution to the bubble dynamics equation, it has been shown that the potential energy of a bubble at its maximum radius due to an acoustic field is negligible compared to that for the hydrodynamic field. Hence, even though the control of hydrodynamic macro cavitation achieved in this way is at the expense of acoustic micro cavitation, it can still be considered to be a significant gain. These are some of the first results in this direction.