Total synthesis of amphidinolide E and amphidinolide E stereoisomers
摘要:
Four amphidinolide E stereoisomers, amphidinolide E (1), 2-epi-amphidinolide E (2), 19-epi-amphidinolide E (3), and 2-epi-19-epi- amphidinolide E (4), have been synthesized via the judicious union of aldehyde 5, allylsilanes 7 or 8, acids 9 or 10, and vinylstannane 6. The C19 stereocenters of the C19 epimeric allylsilanes 7 and 8 were introduced via crotylboration reactions early in the synthesis. [3+2] Annulation reactions of aldehyde 5 with allylsilanes 7 and 8 were employed to set the core tetrahydrofuran units of 1-4. Finally, the C2 stereo-center was installed by esterification using acid 9, without incident, or with acid 10, in which case an unexpected and completely stereoselective inversion of C2 occurs. (C) 2007 Elsevier Ltd. All rights reserved.
A convergent and highly stereocontrolledsynthesis of amphidinolide E (1) has been accomplished. The synthesis features a highly diastereoselective (>20:1) BF3.Et2O promoted [3+2] annulation reaction between aldehyde 3 and allylsilane 4 to afford substituted tetrahydrofuran 2.
Iron-catalyzed enediene carbocyclizations. The total synthesis of (−)-gibboside
作者:James M. Takacs、Suresh Vayalakkada、Steven J. Mehrman、Celia L. Kingsbury
DOI:10.1016/s0040-4039(02)01662-3
日期:2002.11
The first totalsynthesis of (−)-gibboside is reported. The route features a novel iron-catalyzed carbocyclization as the key step for the construction of the cis,trans,cis-tetrasubstituted cyclopentane core.