(R)-(+)- and (S)-(-)-5-Ethyl-5-methyl-1,3-dioxolane-2,4-dione reagents for the direct preparation of .alpha.-hydroxy-.alpha.-methylbutyrate esters: assignment of the absolute configuration of the .alpha.-acetoxy-.alpha.-methylbutyrate ester side chain of quassimarin via total synthesis
作者:Eric D. Moher、Paul A. Grieco、Jon L. Collins
DOI:10.1021/jo00067a004
日期:1993.7
The preparation and use of (R)-(+)- and (S)-(-)-5-ethyl-5-methyl-1,3-dioxolane-2,4-diones for the direct preparation of chiral alpha-hydroxy-alpha-methylbutyrate esters are described.
Synthetic studies on quassinoids: total synthesis of (-)-chaparrinone, (-)-glaucarubolone, and (+)-glaucarubinone
作者:Paul A. Grieco、Jon L. Collins、Eric D. Moher、Thomas J. Fleck、Raymond S. Gross
DOI:10.1021/ja00067a025
日期:1993.7
The total synthesis of (-)-chaparrinone (3), (-)-glaucarubolone (4), and (+)-glaucarubinone (3) is described. The synthesis features an intermolecular Diels-Alder reaction between dienophile 6 and (E)-4-methyl-3,5-hexadienoic acid (17) in 5.0 M lithium perchlorate-ethyl acetate. Diels-Alder adduct 16 is converted via a two-step process into tetracyclic lactone 10. Inversion of configuration at C(9)