A Direct and Efficientα-Selective Glycosylation Protocol for the Kedarcidin Sugar,L-Mycarose: AgPF6 as a Remarkable Activator of 2-Deoxythioglycosides
摘要:
The α-selective effect and potency of AgPF6 on readily prepared 2-deoxythioglycosides allows the direct attachment of a partially protected allo-sugar, such as L-mycarose, to an advanced and hindered aglycon unit of kedarcidin. This method also permits access to other 2-deoxyglycosides in an expedient and mild manner. PMBM=p-methoxybenzyloxymethyl, Alloc=allyloxycarbonyl, TES=triethylsilyl.
The α-selective effect and potency of AgPF6 on readily prepared 2-deoxythioglycosides allows the direct attachment of a partially protected allo-sugar, such as L-mycarose, to an advanced and hindered aglycon unit of kedarcidin. This method also permits access to other 2-deoxyglycosides in an expedient and mild manner. PMBM=p-methoxybenzyloxymethyl, Alloc=allyloxycarbonyl, TES=triethylsilyl.
Kedarcidin Chromophore: Synthesis of Its Proposed Structure and Evidence for a Stereochemical Revision
作者:Feng Ren、Philip C. Hogan、Alan J. Anderson、Andrew G. Myers
DOI:10.1021/ja071205b
日期:2007.5.1
enantioselective synthesis of the proposed structure of kedarcidinchromophore (1) is described. The route is 24 steps in the longest linear sequence (beginning with the commercial reagent 2,3-O-isopropylidene-d-erythronolactone) with an average yield of 75% per step (overall yield: 0.1%). Our 1H NMR data for 1 do not coincide with the data reported for kedarcidinchromophore. We have re-analyzed the original