1248 45 - Asymmetric synthesis 13. The unsaturated amine A, a useful intermediate in the synthesis of the amaryllidaceae (daffodil) alkaloids, can be made from the three starting materials shown below. What kind of chemistry is required in each case? Which is best adapted for asymmetric synthesis? Outline your chosen synthesis. 10. Describe the stereochemical happenings in these processes. You should use terms like diastereoselective and diastereotopic where needed. If you wanted to make single enantiomers of the products by these routes, at what stage would you introduce the asymmetry? (You are not expected to say how you would induce 11. Both of these bicyclic compounds readily undergo hydro14. Suggest syntheses for single enantiomers of these comgenation of the alkene to give the syn product. Explain why pounds. asymmetric hydrogenation of only one of the compounds would be of much value in synthesis. no. E* 12. Explain the stereochemistry and mechanism in the synthesis 15. Suggest a synthesis of any stereoisomer (for example, R,Z ) of of the chiral auxiliary 8-phenylmenthol from (+)-pulegone. After the reduction with Na in i-PrOH, what is the minor (13\%) component of the mixture? this compound. R(+)-pulegone EtOHKOH 16. Revision. Give mechanisms for the steps in the synthesis of tazadolene in Problem 2. reflux