1. Retro-aldol is an aldol addition reaction in the reverse direction. a. First let's practice recognizing the molecular unit that is the starting material for a retro aldol reaction. Notice that this is the same molecular unit that is formed by aldol addition. Circle the beta hydroxy carbonyl unit in each of the molecules. R1 b. Draw a squiggly line to indicate which bond is cleaved by a retro aldol (see example). HIC i CHO HO. CH3 OH H3C -CH3 H3C OH HO CH3 H3C OH OH OH OH R2 c. Repeat the above for the following molecule and then draw arrow-pushing mechanism for a non-enzymatic retro-aldol reaction. H ད་ག་པའི་ཞུ་ H₂O/HO OH d. Draw arrow-pushing mechanism for an enzymatic retro-aldol reaction of the following hexose. Use B: and/or HA as needed. OH OH OH OH OH e. Check your answer for part d. Use the products you got in part d as reactants for an aldol addition reaction. Write an arrow pushing mechanism for enzymatic reaction

Draw the major product of the aldol addition reaction between two of equivalents of this aldehyde with the conditions provided. Ignore inorganic byproducts. 1. NaOH H 2. Neutralizing work-up Atoms, Bonds and Rings Charges Draw or tap a new bond to see suggestions. Undo .༡ Reset > Remove Done Drag To Par

Give the product of the aldol condensation.

This reaction is an example of conjugate addition of a nucleophile to an a,ẞ-unsaturated carbonyl. H3C LOCH3 H₂O H3C OCH3 OCH3 Draw the two resonance structures of the enolate anion intermediate for this reaction. • Draw an R1 group in place of CoA. The R group tool is located in the charges and lone pairs drop-down menu. • Draw one structure per sketcher. Add additional sketchers using the drop-down menu in the bottom right corner. Separate resonance structures using the symbol from the drop-down menu. • O H CH3 ? [F