Synthesis of 15-deoxy-16.beta.-ethoxybruceantin and synthetic efforts toward bruceantin
摘要:
Utilization of asymmetric Michael addition leads to chiral phenanthrenone (+)-4 suitable for the synthesis of Bruceantin. The D-ring is assembled by means of an intramolecular alkylation of the bromoacetals 25 while only the axial diastereomer 25ax proceeds smoothly. The formation of the cyanohydrin introduces the C-13 carborxyl group and tandem intramolecular alkylation provides the furan E-ring. The C-11,12 cis-diol 39 is readily transformed to the trans-diol 42 via an unusual Swern-type oxidation/reduction sequence. The C-2,3 olefin proves to be an efficient progenitor for the A-ring diosphenol function which can be introduced at the late stage of the synthesis. 15-Deoxy-16 beta-ethoxybruceantin 3 is accordingly prepared. Attempts to elaborate common intermediates toward the synthesis of bruceantin are described. The presence of an oxygen function at C-15 drastically changes the relative reactivity of the C-2,3 and C-11,12 olefinic bonds.
Synthesis of 15-deoxy-16.beta.-ethoxybruceantin and synthetic efforts toward bruceantin
摘要:
Utilization of asymmetric Michael addition leads to chiral phenanthrenone (+)-4 suitable for the synthesis of Bruceantin. The D-ring is assembled by means of an intramolecular alkylation of the bromoacetals 25 while only the axial diastereomer 25ax proceeds smoothly. The formation of the cyanohydrin introduces the C-13 carborxyl group and tandem intramolecular alkylation provides the furan E-ring. The C-11,12 cis-diol 39 is readily transformed to the trans-diol 42 via an unusual Swern-type oxidation/reduction sequence. The C-2,3 olefin proves to be an efficient progenitor for the A-ring diosphenol function which can be introduced at the late stage of the synthesis. 15-Deoxy-16 beta-ethoxybruceantin 3 is accordingly prepared. Attempts to elaborate common intermediates toward the synthesis of bruceantin are described. The presence of an oxygen function at C-15 drastically changes the relative reactivity of the C-2,3 and C-11,12 olefinic bonds.
Synthesis of 15-deoxy-16.beta.-ethoxybruceantin and synthetic efforts toward bruceantin
作者:Charles K.-F. Chiu、S. V. Govindan、P. L. Fuchs
DOI:10.1021/jo00081a008
日期:1994.1
Utilization of asymmetric Michael addition leads to chiral phenanthrenone (+)-4 suitable for the synthesis of Bruceantin. The D-ring is assembled by means of an intramolecular alkylation of the bromoacetals 25 while only the axial diastereomer 25ax proceeds smoothly. The formation of the cyanohydrin introduces the C-13 carborxyl group and tandem intramolecular alkylation provides the furan E-ring. The C-11,12 cis-diol 39 is readily transformed to the trans-diol 42 via an unusual Swern-type oxidation/reduction sequence. The C-2,3 olefin proves to be an efficient progenitor for the A-ring diosphenol function which can be introduced at the late stage of the synthesis. 15-Deoxy-16 beta-ethoxybruceantin 3 is accordingly prepared. Attempts to elaborate common intermediates toward the synthesis of bruceantin are described. The presence of an oxygen function at C-15 drastically changes the relative reactivity of the C-2,3 and C-11,12 olefinic bonds.