Abstract
Treatment of 6-methylcyclohex-2-enone (8) and hexa-3,5-dien-1-ol (14) either in dichloromethane at -20 to 0 o C with aluminum chloride (1 equiv) or in acetonitrile at -20 o C with Cu(II) trifluoromethanesulfonate (1 equiv) rapidly provides in a highly stereoselective reaction the hemiacetal Diels-Alder adduct 15, which with a trans ring junction and anti methyl group is considered to arise via an ionic Gassman-type Diels-Alder reaction involving prior formation of a hemiacetal between the alcohol and enone followed by generation of an allylic cation from the hemiacetal mediated by the Lewis acid. The adduct 15 is then converted in straightforward fashion into the methyl ester of the desdimethyl analogue of qinghao (artemisinic) acid, which upon sequential photosensitized oxygenation and then Fe(phen) 3 (PF 6 ) 3 /copper(II) triflate catalyzed cleavage-oxygenation provides (±)-6,9-desdimethylqinghaosu
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
