Study Towards The Total Synthesis Of Virgatolides A-C

ortho-Quinone methides(o-QMs) were first suggested by Fries, in 1907, which(o-QMs) are a kind of short-lived and highly reactive intermediates in organic synthesis. The unstability nature of o-QMs is due to their propensity to undergo rapid rearomatisation either by Michael addition of nucleophiles or, often more usefully, by cycloaddition with 2? partners or via oxa-6?-electrocyclisation to give benzopyrans.As the reason, ortho-quinone methide(o-QM) were always used in the synthesis of natural products through Michael addition and cycloaddition. As the new member of the family of inherently reactive species, ortho-quinone methides are more attractive than radicals, carbocations, carbenes and so forth. And using o-QMs to form skeletons of natural products became a very useful stratergy. This thesis relates to the major application of o-QMs in the synthesis of natural products during 2009 to 2014 and the studies towards the total syntheses of the natural products Virgatolides A-C,which involved the following two chapters:Chapter 1. Application of o-QMs in the syntheses of natural products.In this section, we reported the main application of o-QMs in the syntheses of natural products and illustrated the chemical properties of o-QMs through exemplified different synthetic examples and showed the efficiency to build the skeleton of natural products, which contain benzopyran, benzo-spiro ketal, and so on. Thus we proposed to use this strategy to synthesize natural products Virgatolides A-C.Chapter 2. Study towards the total syntheses of Virgatolides A-C.In this section, I introduced the structural characteristics, isolation and the biological activity of Virgatolides A-C. Base on the retro-synthesitic route of Virgatolides A-C, we synthesized the skeleton of them through the HDDA reaction,o-QM Diels-Alder, Julia Olefination and Fleming-Tamao oxidation.