Silicon-mediated olefination Flashcards
1
Q
Which are more reactive - alpha-silyl carbanions or phosphorus-stabilised anions?
A
Alpha-silyl. Particularly useful for sterically hindered carbonyls (when Wittig reagent fails)
2
Q
Describe outcome of B-hydroxysilane elimination
A
Undergo under basic and acidic conditions. Stereochemical outcome (E/Z) depends on conditions and stereochemistry of starting B-hydroxysilane.
Base-mediated: requires synperiplanar, eclipsed
Acid-mediated: antiperiplanar, staggered