CHEM 2211 1st Edition Lecture 27Outline of Last LectureI. Diels-Alder ReactionsOutline of Current LectureI. Diels-Alder StereochemistryLecture NotesI. Diels Alder StereochemistryA. ENDO vs. EXOi. Endo means that the substituents are facing downwards relative to the moleculeii. Exo means the substituents are facing upward relative to the moleculeiii. To visualize endo and exo, the compound formed from a diels-alder reaction must be drawn in 3Div. The Endo position is the preferred position and is formed the most rapidlyB. The stereochemistry of the diene and the dienophile don’t change during the reactioni. The inside substituents ( the circled hydrogens) always point upwards in the ring that formsii. The carbonyl groups are still trans to each otherAnother exampleFlipping the dienophile forms the endo enantiomer of the
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