Ch. 16 - Conjugated SystemsSee all chapters
All Chapters
Ch. 1 - A Review of General Chemistry
Ch. 2 - Molecular Representations
Ch. 3 - Acids and Bases
Ch. 4 - Alkanes and Cycloalkanes
Ch. 5 - Chirality
Ch. 6 - Thermodynamics and Kinetics
Ch. 7 - Substitution Reactions
Ch. 8 - Elimination Reactions
Ch. 9 - Alkenes and Alkynes
Ch. 10 - Addition Reactions
Ch. 11 - Radical Reactions
Ch. 12 - Alcohols, Ethers, Epoxides and Thiols
Ch. 13 - Alcohols and Carbonyl Compounds
Ch. 14 - Synthetic Techniques
Ch. 15 - Analytical Techniques: IR, NMR, Mass Spect
Ch. 16 - Conjugated Systems
Ch. 17 - Aromaticity
Ch. 18 - Reactions of Aromatics: EAS and Beyond
Ch. 19 - Aldehydes and Ketones: Nucleophilic Addition
Ch. 20 - Carboxylic Acid Derivatives: NAS
Ch. 21 - Enolate Chemistry: Reactions at the Alpha-Carbon
Ch. 22 - Condensation Chemistry
Ch. 23 - Amines
Ch. 24 - Carbohydrates
Ch. 25 - Phenols
Ch. 26 - Amino Acids, Peptides, and Proteins

Photochemical Cycloaddition Reactions

See all sections
Conjugation Chemistry
Stability of Conjugated Intermediates
Allylic Halogenation
Conjugated Hydrohalogenation (1,2 vs 1,4 addition)
Diels-Alder Reaction
Diels-Alder Forming Bridged Products
Diels-Alder Retrosynthesis
Molecular Orbital Theory
Drawing Atomic Orbitals
Drawing Molecular Orbitals
Orbital Diagram: 3-atoms- Allylic Ions
Orbital Diagram: 4-atoms- 1,3-butadiene
Orbital Diagram: 5-atoms- Allylic Ions
Orbital Diagram: 6-atoms- 1,3,5-hexatriene
Orbital Diagram: Excited States
Pericyclic Reaction
Thermal Cycloaddition Reactions
Photochemical Cycloaddition Reactions
Thermal Electrocyclic Reactions
Photochemical Electrocyclic Reactions
Cumulative Electrocyclic Problems
Sigmatropic Rearrangement
Cope Rearrangement
Claisen Rearrangement
Additional Sections
Conjugated Halogenation
Diels-Alder Regiospecficity
Diels-Alder Asymmetric Induction
Diels-Alder Synthesis
Allylic SN1 and SN2
Cumulative Orbital Diagram Problems
Cumulative Cycloaddition Reactions
Cumulative Sigmatropic Problems
UV-Vis Spect Basics
UV-Vis Spect Beer's Law
Molecular Electronic Transition Therory
Woodward-Fieser Rules

Photochemical Cycloaddition reactions are pericyclic reactions in which 2 pi bonds are destroyed after a light-activated cyclic mechanism. 

Concept #1: MO Theory of Photochemical Cycloadditions

Concept #2: Cycloadditions Summary Chart

  • Cycloadditions Summary:

Practice: Use FMOT to predict the mechanism and products for the following cycloaddition. If no product is favored, write “symmetry-disallowed” in place of the product. 

Practice: Use the cycloaddition summary rules to verify that you have come to the correct conclusion.

Had enough of Cycloadditions? If so don't worry because we will now move on to a new kind of pericyclic reaction: Electrocyclic reactions.