Stereoselective reactions. VIII. Stereochemical requirement for the benzylic oxidation of lignan lactone. A highly selective synthesis of the antitumor lignan lactone steganacin by the oxidation of stegane.
作者:TSUNEO ISHIGURO、HIDEMICHI MIZUGUCHI、KIYOSHI TOMIOKA、KENJI KOGA
DOI:10.1248/cpb.33.609
日期:——
A highly efficient synthesis of the antitumor steganin lignan steganacin (1) was accomplished. Bromination of stegane (7) with N-bromosuccinimide followed by treatment with aqueous tetrahydrofuran afforded steganol (3) in 85% yield. Acetylation of 3 gave 1 in 72% yield. Stegane (7) was also oxidized with 2, 3-dichloro-5, 6-dicyano-1, 4-benzoquinone in AcOH to give 1 directly in 10% yield. Stereochemical requirements for the benzylic oxidation of dibenzocyclooctadiene lignan lactones are discussed.
Asymmetric total synthesis of natural (-)-and unnatural (+)-steganacin
作者:Kiyoshi Tomioka、Tsuneo Ishiguro、Yōichi Iitaka、Kenji Koga
DOI:10.1016/s0040-4020(01)82416-9
日期:1984.1
A virtually complete asymmetric control in the synthesis of 2,3-disubstituted butan-4-olide (10) was demonstrated by employing the butenolide (12) as the chiral acceptor for the conjugate 1,4-addition. Highly efficient asymmetric total synthesis of natural (-)- and unnatural (+)-steganacin was accomplished. The absolute stereostructure of natural antitumor steganain was determined to be 1.