Approaches to sesquiterpenes containing three contiguous quaternary carbon atoms. Synthesis of 3-methoxythapsene

Synthetic approach to 3-alkoxythapsane, comprising of the carbon framework of a small group of sesquiterpenes containing three contiguous quaternary carbon atoms has been described. A combination of alkylation, orthoester Claisen rearrangement and intramolecular diazoketone cyclopropanation has been employed for the creation of the three requisite contiguous quaternary carbon atoms

First total synthesis of (±)−β(\pm)-\beta-Microbiotene,(±)(\pm)-Microbiotol and (±)(\pm)-Cyclocuparenol

First total syntheses of cyclocuparanes mentioned in the title have been achieved starting from Hagemann's ester via the bicyclo[4.3.1]nonanedione 8

Regioselective synthesis of bicyclo[4.2.1]nonane-2,8-diones via BF3.Et2O mediated intramolecular diazo ketone insertion reaction

Treatment of the diazo diones 11a-d with boron trifluoride diethyl etherate furnished the bicyclo[4.2.1]nonane-2,g-diones 15a-d in a highly regioselective manner. (C) 1999 Elsevier Science Ltd. All rights reserved

The first total synthesis of (±)(\pm)-grimaldone

The first total synthesis of $(\pm)$-grimaldone, a tricyclic sesquiterpene containing three contiguous quaternary carbon atoms, and $(\pm)$-epigrimaldone along with $(\pm)-\alpha$-cuparenone starting from Hagemann’s ester is described