Asymmetric Total Synthesis Of Benzopyrans And Dibenzopyrans Natural Products

The dissertation aims at the studies on the asymmetric total synthesis of a few naturally occurring benzopyrans and dibenzopyrans compounds. It consists of the following three parts:Chapter 1. S_n2' addition of organocopper reagents to vinyloxiranes and application in syntheses (review)According to different vinyloxiranes, the review introduced some representative synthetic studies based on the stereo- and regiochemical aspects of the S_n2' reactionChapter 2. First asymmetric total synthesis of several benzopyrans derivativesThe syntheses of benzopyrans compounds and synthetic methods for the benzopyran ring were introduced briefly. Using the commercially available hydroquinone and resorcin as starting materials, constructing benzopyran ring with 2-methyl-3-butene-2-ol in acid condition, a series of benzopyrans compounds were conveniently prepared for the first time, in which Sharpless asymmetric dihydroxylation and Jacobsen's catalytic asymmetric epoxidation were the key steps.Chapter 3. First asymmetric total synthesis of dibenzopyran compound Machaeriol DThe total syntheses of the non-natural hexahydrocannabinol (HHC) in recent years are reviewed in details. Using (S)-Carvone as starting material, a facile and general approach to hexahydrodibenzopyrans derivatives has been developed on thebasis of high regio- and stereoselectivity S_N2' addition of arylcyanocuprate tooptically active enol silyl ether of a,β-epoxycyclohexanone. one of the more complex HHDBP's, (+)-Machaeriol D has been synthesized for the first time.