Studies directed toward the total synthesis of cerorubenic acid-III. 1. Expedient construction of the tetracyclic core by oxyanionic sigmatropy
摘要:
A synthesis of the ABCD ring framework of cerorubenic acid-III is described. Diketone 5 was first prepared by intramolecular oxidative coupling of the dienolate 10 and then suitably desymmetrized to deliver 15b. Anionic oxy-Cope rearrangement of this intermediate resulted in construction of 18, a ketone not only having all three contiguous stereogenic centers properly established but also equipped with adequate functionality for the further elaboration of ring D. In the present effort, this thrust took the form of homologation to 21, conversion to the activated diene 22, and Diels-Alder cycloaddition to methyl acrylate at high pressure. Once it became obvious that first-formed ketone 26 greatly preferred adoption of trans stereochemistry at the ring juncture, attempts to skirt this issue were made by preparing both 29 and 32. However, these advanced intermediates proved unresponsive to conjugate reduction, and attention was therefore redirected to alternative possible means for elaboration of the eastern sector.
Details are given for the synthesis of 5-methyl-1-(ketoisobutenyl) bicyclo [3:3:1] nonan-3-one (X) and its attempted conversion into a clovene precursor (XI) is described.
INTRAMOLECULAR OXIDATIVE COUPLING OF A BISENOLATE: 4-METHYLTRICYCLO[2.2.2.03,5]OCTANE-2,6-DIONE
作者:Poupart, Marc-André、Lassalle, Gilbert、Paquette, Leo A.
DOI:10.15227/orgsyn.069.0173
日期:——
Farmer; Ross, Journal of the Chemical Society, 1925, vol. 127, p. 2368
作者:Farmer、Ross
DOI:——
日期:——
POUPART, MARC-ANDRE;PAQUETTE, LEO A., TETRAHEDRON LETT., 29,(1988) N 3, 269-272
作者:POUPART, MARC-ANDRE、PAQUETTE, LEO A.
DOI:——
日期:——
Studies directed toward the total synthesis of cerorubenic acid-III. 1. Expedient construction of the tetracyclic core by oxyanionic sigmatropy
作者:Leo A. Paquette、Marc Andre Poupart
DOI:10.1021/jo00068a019
日期:1993.7
A synthesis of the ABCD ring framework of cerorubenic acid-III is described. Diketone 5 was first prepared by intramolecular oxidative coupling of the dienolate 10 and then suitably desymmetrized to deliver 15b. Anionic oxy-Cope rearrangement of this intermediate resulted in construction of 18, a ketone not only having all three contiguous stereogenic centers properly established but also equipped with adequate functionality for the further elaboration of ring D. In the present effort, this thrust took the form of homologation to 21, conversion to the activated diene 22, and Diels-Alder cycloaddition to methyl acrylate at high pressure. Once it became obvious that first-formed ketone 26 greatly preferred adoption of trans stereochemistry at the ring juncture, attempts to skirt this issue were made by preparing both 29 and 32. However, these advanced intermediates proved unresponsive to conjugate reduction, and attention was therefore redirected to alternative possible means for elaboration of the eastern sector.