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Chapter 25 Suggested solutions for Chapter 25 201 of the problem Chapters 10 and 16 to show that stereochemical as well as mechanistic considerations solution ic acid group is there both to ensure that conjugate addition is possible and to provide attachment for a resolving agent. Quinine is a naturally occurring base and forms a salt Loro-acid that can be separated into diastereoisomers. Acidification of the salt releases the pure acid. H CI CI 0 CI HCI quinine OH H CI CI CI 1. crystallize H + and CO QH 2. separate 2 QH CO₂ QH involves addition to the carbonyl group and loss of the OH group, probably as an compound, to give the aldehyde, which is further reduced by simple addition to the CI 0 CI 0 CI 0 CI OAIH₂ OAIH₂ H H 13 of Chapters 9 and 19. Draw the structures of the intermediates in this synthesis of and comment on the selectivity of the last step. 1. Mg, H A 2. 0 OMe OMe of the problem Chapters 9 and 19 to show that regioselectivity as well as mechanistic considerations solution of a Grignard reagent and its direct addition to the enone are expected. The controlled elimination via the stable tertiary allylic carbocation) gives the substituted conjugated alkene inside the six-membered ring. OMe A