4. a. Compound V is prepared from compounds T and U as shown below: H2O,NaOH(excess)100CC19H18O T (i) Draw the structure of compound V. [2 marks] (ii) Draw and discuss in detail the reaction mechanism for the formation of compound V from starting materials T and U. What is the name of this type of reaction? [13 marks] b. Compounds W and X can undergo a Diels Alder reaction to form two regioisomeric products Y and Z as shown in Scheme 7. W x Scheme 7 (i) Draw the structures of compounds Y and Z. [2 marks] (ii) Using possible resonance contributors of W and X predict which of the two regioisomers will be favoured in the reaction. [5 marks] (iii) Draw the mechanism for the reaction of W and X to form the dominant regioisomer you have predicted in your answer to part (ii) above. [3 marks] (iv) In a Diels-Alder cycloaddition reaction, the diene should be in an s-cis conformation. Explain, using orbital diagrams, why this must be the case. [5 marks]