are listed in Table II; Table III lists the crystallographically determined bond distances and angles (Tables I-II) (listings of observed and calculated structure factors amplitudes are available from the authors); a figure which shows a computer-generated stereodrawing with anisotropic thermal ellipsoids of the compound (5 pages). Ordering information is given on any current masthead
Salts derived from alkylation of propionamides or fluoroacetamides with methyl triflate or dimethyl sulfate reacted with the lithium alkoxide of ( E )or (Z)-2-buten-1-01 at room temperature to yield directly the product of 3,3-sigmatropic rearrangement of the corresponding N,Oketene acetals.Sir: We have found that propionamides as well as fluoroacetamides may be utilized in a diastereoselective amide acetal Claisen rearrangement at room temperature. The Claisen rearrangement,l a powerful synthetic transformation, creates two new asymmetric centers diastereoselectively while concomittantly forming regio-and stereospecifically a new double bond. The sigmatropic rearrangement of N,O-ketene acetals, first developed by Es-
A short synthesis of 2-deoxy-2-fluoro-ribo-D-pentopyranose f r o m the diastereofacially selective reaction between glyceraldehyde acetonide and the lithium enolate of ethyl fluroacetate is described.
2-Deoxy-2-fluorocarbohydrates have found considerable functionalization of the substrate sugar2 prior to fluorination. utility in anti-viral drugs, such as 2-fluoro-5'-iodo-Even with recent advances in direct fluorination3 and in the arabinosylcytosine, FIAC, and 2-fluoro-5'-methylarabinosyl-fluorination of a r ~i o n s , ~ contemporary fluorination methods5 uracil, FMAU.1 2-Deoxy-2-fluoropentoses have been pre-still have several significant drawbacks, requiring the use of pared by several different procedures: however all these reagents which are expensive or difficult to prepare. procedures require several steps for the protection and The synthesis of 2-deoxy-2-fluoropentoses by the addition
Die Lactone (II) und (III) entstehen entsprechend dem Reaktionsschema aus dem Ester (I) in einer dreistufigen Synthese und werden als Gemisch zu den anomeren Tridesoxy‐hexosen (IVa) und (IVb) reduziert.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.