gem-disubstituent effect: theoretical basis and synthetic applications.

3. Synthetic Applications 1746 3.1. Pericyclic Reactions 1747 3.1.1. Diels−Alder Cycloadditions 1747 3.1.2. Dipolar Cycloadditions 1749 3.1.3. Ene Reactions 1750 3.1.4. Claisen Rearrangements 1750 3.2. Radical Cyclizations 1750 3.3. Transition-Metal-Catalyzed Cyclizations 1753 3.4. Ring-Closing Metathesis 1754 3.5. Electrophilic Cyclizations 1755 3.6. Other Cyclizations 1756 4. Biochemical and Pharmaceutical Implications 1757 4.1. “Trimethyl Lock Effect” 1757 4.2. gem-Dialkyl Substitution in Drug Design 1759 5. Miscellaneous 1762 5.1. gem-Disubstituent Effect on the Formation and Stability of Inorganic and Organometallic Complexes 1762