Expeditious asymmetric synthesis of a stereoheptad corresponding to the C(19)-C(27)-ansa chain of rifamycins: Formal total synthesis of Rifamycin S

In the presence of sulfur dioxide and an acid promoter, (-)-(1E,3Z)-2-methyl-1-((1S)-1-phenyleth- oxy)penta-1,3-dien-3-yl isobutyrate reacts with (Z)-3-(trimethylsilyloxy)-pent-2-ene giving a silyl sulfinate intermediate that undergoes, in the presence of palladium catalyst, a desilylation and retro-ene elimination of SO2 with formation of (-)-(1Z,2S,3R,4S)-1-ethylidene-2,4-dimethyl-5-oxo-3-((1S)-1-phenylethoxy )-heptyl isobutyrate as major product. This ethyl ketone undergoes cross-aldol reaction with (2S)2-methyl-3-[(tert-butyldimethylsilyl)- oxy]propanal giving an aldol that is reduced into a stereoheptad corresponding to the C(19)-C(27)-segment of Rifamycins with high diastereoselectivity and enantiomeric excess.


Published in:
Chemistry-a European Journal, 11, 2, 465-476
Year:
2005
ISSN:
0947-6539
Keywords:
Note:
Ecole Polytech Fed Lausanne, Swiss Fed Inst Technol, Lab Glycochem & Asymmet Synth, BCH-1015 Lausanne, Switzerland.
Other identifiers:
Laboratories:




 Record created 2005-11-09, last modified 2018-12-03


Rate this document:

Rate this document:
1
2
3
 
(Not yet reviewed)