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For α,β-unsaturated ketones (enones), 1,4-addition (Michael) competes with 1,2-addition. Soft nucleophiles prefer:
ANeither
B1,2
CBoth equally
D1,4 (Michael acceptor)
Answer & Solution
Correct answer: D. 1,4 (Michael acceptor)
HSAB principle: soft nucleophiles (e.g., R₂CuLi, RS⁻) attack soft C=C of enone (1,4 addition / Michael). Hard nucleophiles (e.g., RMgX, RLi) attack hard C=O (1,2 addition). Synthetic strategy.
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