However, it is interesting to note that the nature
of the nucleophile can also determine the stereo-chemical course of the reaction in the case of (Z)-alkenes as substrates. Low-order cuprates displayed
Felkin selectivity for both (E) and (Z)-147(Table 22,
entries 2, 5), while high-order cuprates predomi-nantly yield the Felkin adduct 148 starting from (E)-147 (entries 1 and 3) but favor theanti-Felkin adduct
149 starting from (Z)-147 (entries 4 and 6). It has
been argued that such reagents initially transfer an
electron to the Michael acceptor, rendering the stag-gered conformation153decisive for the stereochem-ical outcome of the reaction (Scheme 44).