A Synthesis of (±)-Ipalbidine Using Sulfur-controlled 6-Exo Selective Radical Cyclization of α-Phenylthio Amide
1999; Elsevier BV; Volume: 50; Issue: 1 Linguagem: Inglês
10.3987/com-98-s(h)13
ISSN1881-0942
AutoresMasazumi Ikeda, Jiro Shikaura, Noriko Maekawa, Kaori Daibuzono, Hirotaka Teranishi, Yoshiko Teraoka, N. ODA, Hiroyuki Ishibashi,
Tópico(s)Legume Nitrogen Fixing Symbiosis
ResumoA synthesis of (+)-ipalbidine (1) has been achieved using Bu3SnHmediated 6-exo selective radical cyclization of 2-13-(pheny1thio)prop-2-enyll-N-[a-@-methoxypheny1)-a-(phenylthio)acetyl]pymdidine (15) as a key step.(+)-Ipalbidine (I) is the aglycone of ipalbine ( 2), an indolizidine alkaloid isolated from seeds of Ipomoea alba L.' A number of methods have so far been reported for the construction of the indolizidine skelet~n,~ and several efforts have culminated in the total synthesis of racemic3 and optically active4 ipalbidine.Herein we wish to report a new synthesis of (+)-ipalbidine using sulfur-controlled 6-exo selective radical cyclization of a-phenylthio amide as a key step.We initiated our investigation by examining the radical cyclization of the 2-(prop-2-enyl)-N-10.It has been reported that (+)-ipalbidine forms hexagonal crystals from benzenelcyclohexane, but the specfic rotation of this material is not reproducible and depends upon the drying conditions because the crystals contain some benzene and cyclohexane.See ref. 3b.
Referência(s)