Q3(d). Methoxybutadienes with acrolein
Write down the structure(s) of the product(s) obtained in the above reactions. Provide suitable justification and propose the mechanisms. [(i) 2-methoxybuta-1,3-diene + acrolein, Δ; (ii) 1-methoxybuta-1,3-diene + acrolein, Δ; schemes given in the paper]
Answer in brief
(i) 4-Methoxycyclohex-3-ene-1-carbaldehyde, the “para” (1,4) adduct. (ii) 2-Methoxycyclohex-3-ene-1-carbaldehyde, the “ortho” (1,2) adduct, mainly cis (endo).
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CoversDiels–Alder reactionortho/para ruleregioselectivityendo ruleacroleinmethoxybutadiene
All parts of Question 3
- 3(a) Cycloocta-1,4-diene to a tricyclic isomer: heat or light15 marks
- 3(b) 3-Phenyl-4-pentenal from 3-(cinnamyloxy)acrylic acid15 marks
- 3(c) Regioselectivity of Hofmann elimination by Newman projections10 marks
- 3(d) Methoxybutadienes with acrolein10 marks