Chem 242 @ Dickinson

The Claisen Reaction

Today we learned the Claisen Reaction. Initially, this is just like an aldol process, but then veers away in two important areas: 1) the addition of the enolate to the C=O does not stop after addition and get protonated, but instead REFORMS the C=O with loss of an alkoxide (just like in normal carboxylic acid derivative chemistry) and 2) the final "product" is deprotonated to give a stabilized enolate, which then MUST be reprotonated by addition of acid. Curiously, this deprotonation is the step that forces the equilibrium in the needed direction.

Just as with aldols, there are mixed and intramolecular (Dieckmann) versions of the Claisen.

We ended with an introduction to the Michael Reaction. On Friday we will continue the theme of addition to conjugated carbonyl systems with looks at the Stork Enamine synthesis and the Robinson Annulation.

Remember, Meagen will be available during her normal Thursday hours and also on Sunday from 6 - 8 in the Althouse Lounge (downstairs).

posted by DCChem @ 10:41 AM