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.
Organic reactions at high pressure. Michael addition of activated acyclic donors with β,⨿-disubstituted enone acceptors.
作者:William G Dauben、John M Gerdes
DOI:10.1016/s0040-4039(00)94290-4
日期:1983.1
Highpressure, 15 kbar (1.5 GPa), Michaeladditions of doubly activated acyclic donors to sterically hinderedenone acceptors with 1,5-diazabicyclo[4.3.0]non-5-ene in acetonitrile affords Michael adducts in 42–82% yield.
Highly Efficient 1,4-Addition of 1,3-Diesters to Conjugated Enones by In/TMSCl
作者:Phil Ho Lee、Dong Seomoon、Kooyeon Lee、Yunkiu Heo
DOI:10.1021/jo026600t
日期:2003.3.1
Organoindium reagents derived from indium and diethyl bromomalonates were added to a wide range of conjugated enones in a 1,4-fashion in the presence of TMSCl under mild conditions, and corresponding oxo-1,3-diesters were obtained in good to excellent yields.
DAUBEN, W. G.;GERDES, J. M., TETRAHEDRON LETT., 1983, 24, N 36, 3841-3844
作者:DAUBEN, W. G.、GERDES, J. M.
DOI:——
日期:——
Process for the preparation of carbazoles and novel carbazole derivatives utilized therein