I am having trouble figuring out the mechanism for this question:
"
The first step in the reaction (pictured below) is the formation of the conjugate base of the starting material. This intermediate will proceed through an E2-type mechanism where CO2 is lost in place of a proton. Provide a step-by-step electron-pushing mechanism that accounts for the stereochemistry. Use perspective representations throughout. Clearly show and name (E/Z) the stereochemistry of the product."Are they talking about the conjugate base of K
2CO
3? And I don't understand how CO
2 is lost...does the base take it? Then how does the carboxylic acid proton stay attached to the substrate?