Stereoselective preparation and reactions of configurationally defined dialkylzinc compounds
The reaction of cyclic and open-chain diastereomerically pure secondary organoboranes with diisopropylzinc allows the preparation of secondary dialkylzinc reagents with good to excellent retention of configuration as shown by deuterolysis and CuI- and Pd0-mediated reactions with electrophiles. The importance of a high boron-zinc exchange rate to obtain high diastereoselectivity has been shown. Improvement of the configurational stability and stereomeric purity of the zinc intermediates has been obtained by using mono-isopinocampheylborane ((-)-IpcBH2) providing optically active dialkylzinc compounds (up to 96% ee) with enhanced diastereoselectivities.
Boudier
A
Institut fur Organische Chemie, Ludwig-Maximilians-Universitat, Munchen, Germany.
Darcel
C
Flachsmann
F
Micouin
L
Oestreich
M
Knochel
P