-Dicarbonyl compounds condense with aldehydes and ketones that do not undergo self-aldol reaction. The products are ,-unsaturated...

β-Dicarbonyl compounds condense with aldehydes and ketones that do not undergo self-aldol reaction. The products are α,β-unsaturated dicarbonyl compounds, and the process goes by the colorful name of Knoevenagel condensation. (a) An example of a Knoevenagel condensation is given below. Propose a mechanism.

(c) The diester shown in the margin is the starting material for the dibromide used in the synthesis of isonootkatone (Problem 45). Suggest a preparation of this diester using the Knoevenagel condensation. Propose a sequence to convert it into the dibromide of Problem 45. 

Problems 45

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NaOCH,CH3, CH;CH,OH CCH3 CH;CCH,CO,CH,CH3 CO,CH,CH3