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Suggest a suitable (iv) Using curly arrows, draw a mechanism to account for the synthetic transformations from 4 to 3 and then to 2.reagent for this reaction. Using curly arrows, draw a mechanism for this reaction.
(ii) 2-Methoxybuta-1,3-diene (9) can react with ethyl propenoate (10) under thermal conditions. Identify the major product of this reaction. Use curly arrows to indicate the bond making and breaking steps which form the product.
3.Usnic acid (12) is a dibenzofuran derivative found in several lichen species and possesses a wide range of biological functions, including antibacterial properties. Usnic acid can be readily formed from compound 11, which can be prepared from compound 13 by a sequence of reactions. (Note: compound 13 is a minor tautomer of compound 13a.)
Carry out a retrosynthetic analysis of compound 13, showing that 14 and 15 are the starting reagents. Your retrosynthetic analysis should clearly indicate the disconnections, the synthons thus generated and the reagents corresponding to each