Question

Answer all please! Thank you in advance.

Many of the condensations we have studied are reversible. The reverse reactions are often given the prefix retro-, the Latin word meaning "backward." Propose mechanisms to account for the following reactions 22-76 CH H CH CH3 н* (b) (а) CH С- (сн), —сно CH ОН (retro-aldol and further condensation) но. (retro-aldol) CH OH (d) "ОСн, CH OН OH H,C-CH-CN СООCH (retro-Michael) (retro-aldol and crossed Claisen)

Answer 1

22-76 н® 5-CHO retro-aidol Mechanisms OH CH3 CH3 HO он FOH, LCHO Botas a Eta CHO -CH3 -CH3 HO, Mechanism BOLK OH -CH3 H3 CH3 21 Az OH :04 Ha

ScH) IS ** TH TH] He | கே HO S0 -69 + C# = H-CN - ------ சிசி-- Mechanism OH CN - CN Deprotenation 1 + CHÚ= CH –CN

CH3 Ha CUOCH3 CHLOH Mechanism CH3 CH3 OH = -OH -COOCH3 TO CH3 OCH? 47 peproteration ro LH2 De protection