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More on: Molecular Orbitals Pericyclic Reactions Electrocyclic Reactions

More on: Molecular Orbitals Pericyclic Reactions Electrocyclic Reactions. y. x. z. mirror in yz plane. Pi Bonding MO (bond along x-axis; orbitals in xy plane). S ymmetrical mirror plane (yz). y. x. z. rotate 180 o about z-axis in xy-plane. Pi Bonding MO

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More on: Molecular Orbitals Pericyclic Reactions Electrocyclic Reactions

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  1. More on: Molecular Orbitals Pericyclic Reactions Electrocyclic Reactions

  2. y x z mirror in yz plane Pi Bonding MO (bond along x-axis; orbitals in xy plane) Symmetrical mirror plane (yz)

  3. y x z rotate 180o about z-axis in xy-plane Pi Bonding MO (bond along x-axis; orbitals in xy plane)

  4. y x z Pi Bonding MO (bond along x-axis; orbitals in xy plane) Antisymmetric about the C2 axis

  5. y x z mirror in yz plane Pi Antibonding MO (bond along x-axis; orbitals in xy plane) Antisymmetric mirror plane (yz)

  6. y x z rotate 180o about z-axis in xy-plane Pi Bonding MO (bond along x-axis; orbitals in xy plane) Symmetric about C2 axis

  7. Bonding Mirror C2 - axis Antibonding node Pi Bond MO A S S A

  8. anti-bonding - p3* 2 nodes SA Energy of an isolated p-orbital non-bonding - p2 1 node AS SA bonding - p1 0 nodes Allylic Resonance allyl radical allyl cation allyl anion

  9. AS anti-bonding M.O. - p4* Energy of isolated p-atomic orbital (A.O.) anti-bonding M.O. - p3* LUMO SA bonding M.O. - p2 HOMO AS SA bonding M.O. - p1 M.O.s of 1,3-Butadiene Lowest Unoccupied Molecular Orbital Highest Occupied Molecular Orbital

  10. AS AS SA SA AS SA Orbital Symmetry in the Diels-Alder Reaction LUMO HOMO Equal HOMO-LUMO Energy Difference

  11. AS AS SA SA AS EWG EWG SA Diels-Alder Reaction with a Deactivated Dienophile LUMO HOMO EWG Lowers LUMO Energy

  12. EWG EWG The Diels-Alder Reaction Transition State Diene HOMO (p2) Dienophile LUMO (p3*)

  13. hn DE Photochemical Excitation in 1,3-Butadiene HOMO photochemical rxn. HOMO thermal rxn.

  14. 1,3-Butadiene Cyclobutene Disrotatory p3* hn Conrotatory p2

  15. but one cyclobutene is just like another cyclobutene enter stereochemistry

  16. 1,3-Butadiene Cyclobutene Me Disrotatory Me Me Me p3* H H hn Me H Conrotatory Me H H Me p2 H Me

  17. trans E,E E,Z cis Stereocontrol in the 1,3-Diene Cyclization hn Dis Thermal Con Thermal Con hn Dis

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