Improved Julia-Kocienski conditions for the methylenation of aldehydes and ketones.
[reaction: see text] The scope of the methylenation of aldehydes and ketones under optimized Julia-Kocienski conditions is broadened by using 1-tert-butyl-1H-tetrazol-5-ylmethyl sulfone. Two different Barbier-type procedures are applied with NaHMDS at -78 degrees C or Cs2CO3 at 70 degrees C. The latter conditions are also adapted for the preparation of 1,2-disubstituted olefins and intramolecular olefination reactions.
Aïssa
Christophe
C
Max-Planck-Institut für Kohlenforschung, D-45470 Mülheim/Ruhr, Germany. aissa@mpi-muelheim.mpg.de