The tandem ring-closing metathesis-isomerization approach to 6-deoxyglycals
1Universität Potsdam, Institut für Chemie, Organische Chemie II, Karl-Liebknecht-Strasse 24-25, Haus 25, 14476 Golm, Germany. bernd.schmidt@uni-potsdam.de
Abstract:
Protected 3,6-dideoxyglycals have been synthesized de novo as single isomers starting from ethyl lactate by using the tandem RCM-isomerization reaction as the key step. Different relative configurations become accessible by addition of vinyl- or allyl-metal compounds to protected lactaldehydes under Cram-chelate or Felkin-Anh control. The concept is exemplified for glycals of L-rhodinose and L-amicetose, as well as for ring-expanded non-natural analogues thereof. This novel approach to glycals is also applicable to the synthesis of disaccharide glycals via a reiterative strategy, as exemplified for the dimer of L-rhodinose and its non-natural ring expanded analogue.
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