Bis(1-cyanovinyl acetate) Is a Linear Precursor to 3-Oxidopyrylium Ions
作者:Sidney Malik Wilkerson-Hill、Shota Sawano、Richmond Sarpong
DOI:10.1021/acs.joc.6b02111
日期:2016.11.18
Herein we describe the first approach to 3-oxidopyrylium ions from a linear precursor. Heating bis(1-cyanovinyl acetate) in the presence of a trace amount of pyridinium p-toluenesulfonate results in a series of acyl group transfers and an intramolecular cyclization event to form a 3-oxidopyrylium ion that can be trapped by reaction with several dipolarophiles. When treated with dienes, the result is
Gold-Catalyzed Cyclopenta- and Cycloheptannulation Cascades: A Stereocontrolled Approach to the Scaffold of Frondosins A and B
作者:David Garayalde、Karolin Krüger、Cristina Nevado
DOI:10.1002/anie.201006105
日期:2011.1.24
Golden cascades: Two diastereoselective gold‐catalyzed cascade processes in which propargyl acetates react with alkenes or 1,4‐dienes afford highly substituted five‐ and seven‐membered rings, respectively (see scheme). The concerted nature of the gold‐catalyzed Cope rearrangement has been used in the formal enantioselective synthesis of marine norsesquiterpenoids Frondosins A and B.