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64 Organic Chemistry Solutions Manual Suggested solution The mechanisms are standard and this is an enone that really might do either. Product B is the result of direct addition followed by loss of a leaving group - a likely reaction as amines saturated esters in this way. This reaction is fully treated in Chapter 12. 0 NHMe₂ 0 NMe₂ NHMe₂ OMe OMe OMe B A Product C is the result of conjugate addition - again a likely reaction as esters are prone to conjugate addition and amines are good nucleophiles for that reaction. 0 0 OMe Me₂NH Me₂NH OMe c A The compounds could be distinguished easily by ¹³C NMR. Product B has the two carbon of the alkene in the 100-150 p.p.m. region while product C has no signals in this region but does have a signal for the OMe group in the 50-100 p.p.m. region as well as more signals in the 0-50 p.p.m. region. In addition, the molecular ions are different in the mass spectrum as B is C₆H₁₁ NO while C is C₇H₁₅NO₂. Problem 5 Suggest mechanisms for the following reactions. OMe OMe NO₂ HOAc EtOH 0 MeHN NO₂ N Me Purpose of the problem To get you to draw mechanisms for more exotic examples of conjugate addition. Suggested solution The nitro group is one of the best activating groups for conjugate addition as it almost never gives direct addition. Even the weakly nucleophilic acetate ion will react as the nitro-stabilized anion is very stable indeed. 0 0 0 NO NO NO₂ 0 1 0 0 AcO H