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Chapter 10 Suggested solutions for Chapter 10 63 must be present during the conjugate addition so that must be done first. The second route lead to the required product. H 0 0 OH 0 HCI CI CI CI the conjugate addition has removed the alkene, direct addition is the only option for the nucleophile. The alternative order of events would probably lead to direct addition by the reagent followed by protonation of the double bond. You were not asked what the product wrong reaction sequence is, but it might be this. o Ho Ho EtMgBr HCI + CI Problem 3 reasons for the different outcomes of the following reactions (your answer must, of include a mechanism for each reaction). 0 R₂NH 0 MeCO₂H, H2O NR₂ Purpose of the problem Revision of the relationship between type of nucleophile and type of reaction. Suggested solution The Michael acceptor is a conjugated ketone that is able to do either direct or conjugate addition. are softer nucleophiles able to add reversibly and more likely to give conjugate addition by control. is very hard and completely irreversible so it gives direct addition kinetic control. If you drew a full mechanism for each reaction, your answer is better than Problem 4 Addition of dimethylamine to the unsaturated ester A could give either product B or C. Draw mechanisms for both reactions and show how you would distinguish them spectroscopically. 0 0 OMe OMe NMe₂ C A B Purpose of the problem To get you to draw the mechanisms for both reactions and to revise NMR.