Asymmetric Synthesis of the C(33) - C(37) Fragment of Amphotericin B
摘要:
We have devised an expeditious. efficient, asymmetric synthesis of the C(33)-C(37) fragment of amphotericin B that proceeds in 14 steps and 16% overall yield from tiglic aldehyde ((E)-2-methylbut-2-enal) with complete stereocontrol. The route described herein relies on the application of recently developed methods in catalytic asymmetric synthesis for stereocontrol through enantio- and diastereoselective functionalization of a substituted sorbate derivative.
Asymmetric Synthesis of the C(33) - C(37) Fragment of Amphotericin B
摘要:
We have devised an expeditious. efficient, asymmetric synthesis of the C(33)-C(37) fragment of amphotericin B that proceeds in 14 steps and 16% overall yield from tiglic aldehyde ((E)-2-methylbut-2-enal) with complete stereocontrol. The route described herein relies on the application of recently developed methods in catalytic asymmetric synthesis for stereocontrol through enantio- and diastereoselective functionalization of a substituted sorbate derivative.
When γ,δ-epoxy-α,β-unsaturated esters or amides were treated with 2 equiv of Grignard reagents in the presence of 10−24 mol % FeCl2, regio- and stereoselective substitution of the epoxide moiety with the Grignard reagent occurred to give exclusively δ-hydroxy-γ-alkyl or aryl-α,β-unsaturated esters or amides in good yields.
Ruthenium-Catalyzed Enyne Cycloisomerizations. Effect of Allylic Silyl Ether on Regioselectivity
作者:Barry M. Trost、Jean-Philippe Surivet、F. Dean Toste
DOI:10.1021/ja046824o
日期:2004.12.1
Ruthenium catalysts effect efficiently such single-step cycloisomerization at room temperature in acetone under neutral conditions. The cycloisomerization functions with (E) or (Z) 1,2-disubstituted alkenes. Parameters influencing the enol silane geometry are discussed. The level of selectivity depends on the alkyne substitution, the geometry of the double bond, and the nature of the catalyst. Furthermore